install new light on existing switch I have a switch that goes to one overhead light.  on the switch is 1 line and the white and black wires are attached.  can I splice in to the line and run a black and white wire to the existing switch and then take the second wire attaching the two white wires together one from the splice and one from the new light and then take the black wire from the light and the wire from the splice to the new light switch.

If the switch has only the traveler wires, with the feed in the light then you basically do not have a neutral at the switch.  So a second switch can not be added at that location with out adding a neutral.  At the light the feed can be "tapped" hot and neutral and ran to a new light with a new traveler to the new switch.


Can a water softener be installed after a thermal expansion tank? Our thermal expansion tank is installed after the meter and feeds into the house and hot water heater. It seems like it should have been installed immediately prior to the water heater...
Can I install a water softener after the thermal expansion tank or should I try to install it between the meter and thermal expansion tank?

I don't think this should be a problem, water softeners I have seen do not have check valves in them so water can flow through both ways. It's only after a check valve where expansion capacity is needed.
Many homes do not even have an expansion tank, they are most frequently found (at least in my area) where there is a pressure regulator (which contain a check valve) installed after the meter. In that case you need an expansion tank (especially with a water heater) because of the additional pressure warmer water will create in the system which needs to be relieved. If there are no check valves in the system the entire city main can serve as the expansion tank (water flows backwards through your meter).


Does there exist such a thing as mini-scaffold? I'm looking to create an anti-RSI workstation.

Something like:

(only that particular one happens to be a scam called NEThrone)

Only what I have in mind is hacking together something using maybe a car seat, an adjustable monitor arm, and some kind of scaffolding rig.

I've used scaffolding in the past, and you can build pretty much any structure with just 2 parts: pipes and clamps.

However, scaffolding is heavy duty, designed to support thousands of kilos. It's going to be very clumsy working with this.

I'm wondering whether there exists some lightweight alternative. Maybe tubes that are a quarter the diameter.

So my question is specifically this: does such a thing exist?

I would imagine people would use something like this to build home-gyms.

PS If anyone can suggest some online community that may be appropriate for enquiring about this project, I would be very grateful. It seems to be off topic everywhere. But this SE site is designed for people who are building their own solutions -- maybe someone can suggest something?

For a professional system, Kee Klamps might be what you are looking for:

For more DIY accessibility, black pipe is a likely candidate:


Electrical dimmer switches for 4 switch locations? I have a bank of 6 - LED 18watt (dimmable) bulbs and this bank has 4 switch locations.  Is it possible to dim this bank?  I don't see any 5 way dimmer switches offered.

Thanks.

There's more than one option!

As ThreePhaseEel points out, Multi-location dimming is one option.

However, depending on usage, specifically the case where the lights will mostly always dimmed at the same level or just having the dimming capability at one location with the existing switch still in operation at the other 3 locations. That is, you'll replace one of the existing 3-way locations, leaving remaining switches untouched.

If this is the case look for just ONE 3-way PRESET dimmer.

One example: Lutron LED compatible PRESET dimmer: http://a.co/aIBfTR0

(Ariadni, Toggler, Diva are all examples of preset in Lutron's product line) (Disclaimer, I don't work for Lutron. I do spec a lot of Lutron product for customers in my day job, as such I know the product lines--my only bonus for selling Lutron is the Lutron rep does take me to lunch 4 times a year.)

If dimmed the same all the time, this solution will be far less pricey than Multi-location, not to mention easier installation.

The only con is that one of the existing 3way locations (not a 4-way) must be picked for the replacement dimmer. If you open up the existing and find the switch has 4 screw terminals, just stop and put it back together and move on to another location.  If the switch you take apart has 3 terminals then the PRESET dimmer can be installed in that location.

Here is a wiring diagram for a 4 location switching. In the diagram, the center two switches are the 4-way switches, the outer two switches are 3-way switches.


How do wire this 2-gang dimmer switch? I'm trying to fit a dimmer switch in my living room. I have two pendent lights controlled by a single wall socket with two switches one for each light. My property is a new build and in the UK.

So much for thinking this would be as easy as unwiring the wires and wiring them into the same places on the new dimmer switch!

My current standard wall socket is wired like so:

This seems a lot more complicated than just a few wires to swap. There appear to be multiple cables coming out from the wall. The Green/Yellow earth is loose in the backplate with a plastic end cap.

The wires in L1 and Com on the first switch are striped towards the end of the wire, the stripped part is then in the L1 or Com socket and then the end of that wire is then kind of bridged into the other L1 or Com socket on the other switch.

My new 2-gang 400W dimmer looks like this:

Problem is new dimmer switch does not have a socket labeled N Loop.
I tried replicating the wiring but where on the original sockets the wires are in the N (Loop) ports, I've just put them in L2 on the new socket as that was the only other port unused.

It seems the old switch has Com, N (Loop), L1 and L2 ports, but the new dimmer socket only has L1, L2 and Com.

I tried this setup and it kind of worked if lights were on and the lights did dim (though flicked, maybe wrong energy bulbs) but when I tried to turn them off they blow trip the fuse in the main fuse box.

As you can probably tell I know nothing about wiring or these kind of things. Any help or pointers anyone could give me would be really appreciated.

I was wondering if I have the wrong type of light switch but I can't find any other types.

I've also included a photo of the instructions though they don't really mean much to me and don't really correspond to the original wiring for the original socket.

All sorted now, basically I have a plastic back box but the earths have a connector on them. The Loop N terminals are for convenience, so I've just bought a connector block to connect them up. The L1 and Coms just need to have the same wiring on the new dimmer switch. I've not done it yet but got my answer from another forum.


What should I do with the ground wire from my light fixture when there's no ground in the box? The ceiling light/fan I want to install has a short GREEN wire. It looks ready to be twisted onto another wire. There is NO ground (bare copper or another green wire) coming out of the ceiling box. What do I attach the short green wire that came with the fan/light to?

This wire is usually connected to a bare wire ground if available, if not available and the box is metal connect it to the box. If you do not have an equipment ground the wire is not used.

Current code allows a ground to be added as long as it comes from the same panel that feeds this circuit (it can come from another circuit if grounded and fed from the same panel)


Filling a crack in a wall with roughcast on limestone Finally, I was not able to Limit the extent of cracks in the wall roughcast, which is finally cracking:

I have removed the crumbling parts, and protected the wall with a plastic sheet waiting for a dry weather.

What is the best method to fill the hole (about 25 cm wide or 10 inches)  and make a clean junction with the borders?

You'll need to pry, chip, scrape & wire brush off any & all loose, soft or mushy stucco, possibly tripling the hole's size. This has to be done if you don't want your patch falling out very or fairly soon after it's done.

But, any stucco, cement or mortar mix does & will work perfectly. Buy a bag of small gravel & insert the gravel into the wet cement product for a very close match to the surrounding pebble-like finish.

That's all I did 20-years ago in my first place & it's still there with no signs of any problems. Additionally, any surface cracks should be finger force caulked with a white latex caulk to avoid more future holes.


Basement leak behind electrical panel I've got an active leak (probably one of the infamous Michigan rod holes) behind the electrical panel in my basement.  It's just seeping at the moment, but after seeping comes dribbling and after dribbling comes gushing, right next to all that electrical stuff --- bad.  I need to get in there and plug the rod hole.  Can I take the electrical panel off the wall to get at the rod hole?  How do I do that?  Do I need to turn the power off?

Clarification: I would like to avoid having to disconnect everything. That would require an electrician or a lot of work. Can I just move the panel?

"Can I take the electrical panel off the wall..."

Yes, but removing it requires the feed conductors and circuit conductors to be disconnected. This is a big job and (depending on your local code authority) a licensed electrician may be a requirement. If you are allowed to DIY and you are comfortable working with conduit, breakers, wire connections, etc., make sure you take a bunch of pictures before and during and label everything carefully.
If you are asking "how do I do that", than I propose you call an electrician.

"Do I need to turn the power off?"

Absolutely. Again, the fact that you are asking makes it clear that to safely complete the project you should call a reputable licensed electrician. It will be worth every penny of the cost, believe me.


Clean up muddy water left after hurricane After Irma, 2 yrs ago, our floor was covered with a wet sticky mud.  I used a massive amount of towels to clean it up. Now I am wondering if a wet dry vac( preferably with a pump )  would make the job easier.  Your thoughts please?

What I've done in the past for mud and other messes is to start with a garden hose to move the mud, using a basic sprayer head. You spray in an arc across the floor and try to get the water & mess flowing in the direction you want.  You can use the squeegee broom mentioned by brhans to help with this. The water not only helps liquefy the mess to make it easier to flow away, but the movement and pressure does the work of moving it for you. You don't even need a pressure washer to get most things clean this way.

If you get really good at this, you can not only get large amounts of mud/mess off the floor, but you can get nearly 100% of it off. I've used the technique so much and figured it out so well that mops were essentially unnecessary for several things I've had to clean off floors. Getting the water to move correctly will prevent puddles and will leave not much more standing water than a mop will.
How thick and/or how large an area it is you need to work with determines your starting point. If it's not thick and not a large area, start at the farthest point away from your exit or drain. This gives you the best shot at getting it done in the fewest passes. And don't worry about trying to clean it all in one pass. With something as messy as mud, it'll likely take several passes, even if there's not much there.
If it's a lot of mud/gunk or it's a large area, start closer to the exit or drain. This allows removal of sections of mess and helps prevent it from flowing back on your already cleaned sections.
If it's really thick, as in more than an inch, then you need to shovel it out first, using a flat bladed shovel, like the image below, or a snow shovel or scoop shovel. Depending on where you need to get it, a wheel barrow, like Jim Stewart mentions, could do the trick. If you can't get one through a door, then 5 gallon buckets can work in a pinch.

Images included for example only.


What might be a good way to fix this damaged drywall(?)? I had 2 3M Command hooks on my wall. When I was removing the hooks, I damaged the wall, as you can see in the photos below. I wonder what might be an easy/good way to patch the damage. Thanks!

It looks like one layer of paper has separated from the other. The paper surrounding the tearout has loose flaps of paper around it too.

Remove all loose paper and give a tight skim coat or two of paste spackle, sand smooth, prime and paint.

You will be wise to get a 4" drywall knife to help in this. The little 1" knife that is considered a putty knife are good for nail holes and window glazing. Check out a YouTube tutorial on drywall paper tear repair


Solar panel as a hatch and Is sleeping under a solar panel safe? I'm looking to build a very large custom roof hatch/vent on my van. I was going to make to top out of Lexan, but then I realized I might want a large solar panel on the roof as well.  I was looking at the aluminum structure of solar panels and read the edges are water tight.  Any reason I can't use the solar panel itself as my hatch top? Structurally I think it will work, and I know panels get hot just like my metal roof gets hot,  but wonder if there are any chemical reactions or gases that will enter the van as a result of the back side of the solar panel working.  I also know solar panels need ventilation underneath, but then again, so does my van inside during a hot day.

wonder if there are any chemical reactions or gases that will enter the van as a result of the back side of the solar panel working

No. Solar panels are inert.

  I also know solar panels need ventilation underneath

Yes. A solar panel has a low albedo, probably much lower than the white roof of your van. So the panel radiates a lot of heat.

Roof hatches on campervans are usually transparent. This has the advantage of bringing natural light into the living space, which makes the cabin feel pleasant and roomy.
An opaque hatch only admits light when it's open, and only through the opening, i.e. light falls in from the side, not the top.

If you go camping in colder weather, you'll want insulation under the solar panel, to prevent the panel forming a cold bridge. Campervan roof hatches are double-pane to provide insulation.

One more consideration: if you use a solar panel as a hatch, make sure the panel can withstand the aerodynamic loads.

during driving, the roof shape, ventilation etc. may create a pressure difference between inside and outside
when stationary, opening the door while the hatch is closed may create a pressure difference between inside and outside, esp when the door is facing the wind direction and it's storming.


Is there hard-water deposits inside the pipes in my house? I have a fairly new home, built in 2007, in Arizona. I noticed today that most of the faucets in our house are starting to get hard water deposits on them where the water is coming out. It got me thinking, the pipes must have similar build-ups, and it can't be good for them. Is there hard-water deposits inside the pipes inside my homes, and if so, is there a fairly quick and easy way to clean the hard-water deposits from out of the pipes? Not the easy ones to get to, mind you, but the pipes in the walls and such. I'm pretty sure the pipes are all PVC, if it makes a difference.

Faucets have screens on them.  Your pipes shouldn't have deposits on them because the sediment will build-up on the bottom of the tank when it is being heated (the change in temperature and stagnation are the main reasons for the sediment falling out of solution -- neither of which happens in pipes,) and it shouldn't go out of the top.  The screens on the faucets are to stop debris that are lighter than water.

That's not to say that it's impossible for pipes to get build-up, but you'd have major water heater problems prior to your pipes getting clogged.  Clean the screens to see if the flow rate / pressure goes up.  If it clears up the problems, no need to mess with the pipes!

(Also, another way to test whether it is merely the screens giving you the problems is to test it using the cold water.  If the cold water is also slow, it's the screen on the faucet, not scale build-up in your pipes.)


Rewiring a small appliance I have a small appliance with a 110vac transformer that broke off where I cannot reconnect it.  Can I replace that 110vac transformer with a 120vac and does it matter which side the wires go on?  Can I miswire?

The transformer can be replaced, 120 /110v transformers are the same thing just different dates when they were manufactured. For many years we called line voltage 110, later 115 now 120 so they by definition are the same to the national electric code in the US. The important part is the output voltage and the size or how many amps / watts it is rated for. The new transformer needs to be rated the same or larger for example 120/24vac at 5 amps the new one needs to be 5 amps or better. The voltage needs to be the same in this case 24v I chose this as it is a very common size.

Can you wire them backwards, Yes if wired backwards where the secondary leads are tied to the mains or 120v the out put will be 600v if the insulation holds up (for this example).
Usually step down transformers have a ground wire on the primary side, most of the time they are stamped with the voltage on each side of the case 2 wires of the same color on the 120v side means it doesn’t matter which one connects to the hot and neutral or normally black and white of the 120v supply.

So make sure your output voltage on the secondary of the transformer is the same as the original and that it is rated for the same load in amps or KW, if the same value is not available go bigger NEVER smaller. And last make sure to hook up the primary side to the supply or mains voltage.


Insulating hard to access rim joist I am currently insulating my rim joists with rigid foam board, then spraying great stuff around the edges. However, there is one rim joist that will be too difficult to get the foam board into because of a steel I-beam.  Would it be a bad idea to spray just this one rim joist with a lot of great stuff?

Only if you get the foam everywhere but where you want it.
If you can't see the location very well, in addition to being difficult to reach, you may not get a "perfect" application of foam, but an imperfect application will still give you more insulation than no application at all.


Is there any reason not to use the trap door ash receptacle in my fireplace? I never used this trap door. Presumably, it's to dispose of ash on a regular basis.
Is there any particular reason that using this is a bad idea? There's a door/ access panel in the basement to clean out the accumulated ash, which makes me wonder what the benefit is of using this. I can just fill a bucket and carry ash away every fer fires.

The benefit is that (with the door below closed as per normal practice) you don't need to wait for anything to cool (it's going into a nice masonry chamber, nothing to burn) and you don't need to carry ash through the house. You dump the ash (hot or cold) down the hole all winter, and when spring comes you shovel it out from the basement and go spread it on your garden (unless you are in an alkali soil area. In acidic soil areas wood ash is quite beneficial to gardens.)
@jstola's nightmare scenario is frankly a bit far-fetched. Those cast iron doors don't just fall open by themselves, and any smoldering combustion byproducts would be filtering up by the trapdoor, into the chimney, and out of the house.


need feedback on radiator heating systems and carbon monoxide I live in an old apartment with radiators for heat, The gas boiler is down two levels in the basement. oddly enough there are no cold air returns...is this correct? Our carbon monoxide alarm continuously goes off when the heat is turned up, we cook on our ELECTRIC STOVE. If we forget to turn the heat down at night, we all wake up with headaches and nausea. What is your guess as to what is wrong.

If your carbon monoxide detector is going off, you have a carbon monoxide problem. Contact your utility or local emergency services for a more thorough test. The symptoms you describe are consistent with early stages of carbon monoxide poisoning.

If your radiators heat with hot water or steam, or another system other than forced air, you will not have return ducts. That is normal. Carbon monoxide inside homes typically originates from a gas-burning appliance directly -- so in your case it would be gases coming up from a heater or boiler (probably in the basement). Alternatively, it could be that the exhaust duct / chimney is leaking into your apartment, rather than completely exhausting outdoors.

Get this looked at right away by professionals. BE VERY CAREFUL and do not venture downstairs; if the CO problem is bad in your apartment, it might be much worse in the immediate surroundings of the heater. Be safe!


Are dual-function AFCI/GFCI breakers less effective than single-purpose GFCI breakers? I have a house with old wires (cloth) that lack ground. I've been advised that we can install GFCI breakers on those circuits to help protect against the lack of ground. But since the wires are cloth, I'm also thinking that AFCI protection would be nice, so I am considering having our electrician put in all dual-function (a.k.a. DFCI) breakers. However, I saw a comment that made me worry the dual function breakers may be less effective:

some people say the combo's don't work quite as well as single purpose GFCI

Is that true? What does "less effective" even mean--longer time before it trips or that it may not trip at all?

They should be equally effective. They have a job (or two jobs) to do, and are designed and tested to do that job.
But I would suspect a higher incidence of False Positives nuisance trips*, particularly since you can't have one part without the other. One option to consider is AFCI via breakers and GFCI via receptacles (first in each chain), which also provides easier reset. AFCI is, generally speaking, protection against either internal wiring problems - e.g., nail through a wire or worn out (or rodent chewed through) insulation - or certain significant failures (backstabs or other bad connections, worn-out electric blankets).
On the other hand, while GFCI does provide protection that can substitute for the "usual" ground wire (since any current that would be going over ground must be "missing" from hot/neutral and therefore an imbalance == GFCI trip), it also provides protection against true device ground-faults and certain temporary problems, particularly due to water getting inside electrical equipment. As a result, having easy and convenient reset for GFCI is potentially more useful than for AFCI. In addition, while AFCI is important for the wires, GFCI is for receptacle/device/people protection, so putting it at point-of-use (first receptacle in the chain) works very well.
*I initially wrote "false positives", thinking like incorrect spam filtering or rapid COVID-19 tests. However, in the case of GFCI trips, the vast majority of trips will be true positives. The issue is that many (not all) of these so-called nuisance trips will be situations that can be resolved easily & safely. Spill water on your toaster (or other appliance with internal exposed wiring) and you will have temporary ground-fault that will be resolved by drying out the appliance. But that trip is still real and potentially deadly, just temporary. Unlike, for example, worn out insulation where the danger never goes away (and the GFCI trips keep happening).


Should I install a damper above my return air duct for better upstairs cooling? I have a finished basement, ground floor, and upstairs. The ground floor and basement cool nicely with the AC. The upstairs doesn't cool very well.

The returns are really just holes in the drywall- there are no ducts behind them. The ground floor has a 30"x6" return vent. The upstairs has that plus 2 15"x7" return vents. I checked last night and there does seem to be decent movement of air into the big upstairs return (one or both of the other two seemed significantly weaker).

My primary question is if it makes sense to block air behind the wall above the upstairs ducts? I'm thinking of using expanding spray foam. My reasoning is it would help seal the inside and create better suction.

I'm open to other ideas too. Since I moved in 4 years ago, I've:

had the attic insulated
had the ducts cleaned and sealed
put supply register boosters on 2 upstairs bedrooms
increased the HVAC blower fan speed

All the things you've done should have helped some, except the duct boosters.  They can't add much flow to the system unless the return ducts were increased proportionally (or similarly boosted).  You get increased flow by increased pressure or larger ducting.  Keeping upstairs doors closed will help by slowing the 'fall' of cooler air downstairs. Try leaving fan "ON" for a 24 hr period to see if your house will equalize better.

You can force the system to concentrate on the upstairs by reducing both the supply and return  vents in the main floor and basement.  You may have to do some makeshift blocking (reduction
) of the returns with plastic sheeting and 'no residue' duct tape.  If successful, I believe magnetic covers are available.

AFA blocking above the upstairs ducts, by all means.  Save yourself some expense (and trouble, that much foam is hard to scaffold in a vertical shaft) and make 2x4 blocking (essentially fire blocking) to go above the vents.  If you have typical framing 16 inches on center, a 14 1/2 inch piece will span stud-to-stud.  Use a pair of pocket screws on each end to secure the blocking in place.  Use fire caulk/foam for any gaps.


How do I remove mineral stains from tiles? The water in our apartment has higher salt levels, which ultimately makes stains on tile.  I tried to remove them with various bleaching agents, but with no effect.  Can anyone help?

i would suggest you try CLR.  It is available in most stores and hardware stores.  If this doesn't work, my question would be what type of tile do you have? Almost sounds like you may have an unglazed type of tile, not a highly glazed porcelain. If you are successful cleaning the tile, you may want to seal the tile to help in the future. You can find tile and grout sealers at any home center.

.


compressor running constantly but ice not dropping the compressor on our refrigerator freezer quit running so we replaced the relay. now the compressor has been running for over 21 hours. the ice maker has made ice but has not dropped the ice. what is the problem?

Sometimes the ice gets stuck in the tray -- there's supposed to be a heater that melts the outside of the ice so it can be pushed out.

Check if there is ice in the icemaking tray.

When this happens, I use a hairdryer to loosen the individual crescents, and push them out with a wooden spoon handle. The cycle usually resets and starts producing ice normally afterwards.


Fridge has a weird smell coming from where the compressor is I have a fridge that has some kind of weird smell coming from where the compressor is. Ive checked the wires and any connections to see if theres any burnt wires, theres nothing. Its not really a burning smell. Its something really weird. Is this dangerous to inhale? What can I do about it?

Is it a rotten food kind of smell, or an "oily" or metallic kind of smell? If not a rotten food type of smell, it may be a refrigerant leak, in which case your compressor is probably toast by now.


How to choose a valve to use when plumbing a huge valve handle to my hose station I am building a hose station in my backyard. For fun, I would like to use a huge vintage valve handle to operate the water coming out of a normal 3/4" hose.

Obviously I can't connect anything like this to my normal hose bib. I have been researching larger valves which I could use to control the flow, (2-3" for instance) but I'm guessing a valve that large will be terrible at modulating the flow of my 3/4" hose.

Can anyone suggest suggest how I would choose a valve that is:

Strong enough to support a giant valve handle such as the one pictured? I presume a wheel this size will put a lot of stress on the valve internals and body. Kids will be using the hose and I would like it to be a durable setup.
Provides the ability to effectively modulate flow of a normal garden hose
Provides 1-2 full revolutions to transition from fully on, to fully off

It's true that is a lot of leverage for most valves that would be appropriate for a water hose.  A large gate valve might work, but you would get a full stream of water even when the valve was opened 1/4 of the way (depending on size, of course).

What I would propose would be a few gears (worm/screw drive?) between this large handle and a 3/4" valve.  If using gears, you can make a large, strong axle to hold the large wheel rather than having it mounted directly to the valve.  The torque available with the large handle could still be a problem, but mechanical stops could prevent over-torquing.

Another idea - use an electric valve to open and close the water hose, sense when the wheel is turned, and activate that valve.  This way you can turn the wheel as much as you want and as fast as you want and the real work is mechanically separated by the electronic valve.  Also, you could design in a timer to automatically close the valve after being on for a set time.

I realize building something like this might be beyond a small DIY project, but it's the best I could come up with beyond using a large valve.  And who knows - you might really enjoy the mechanical or electronics challenge.


How can I clean an air compressor tank? I have a Dewalt Air Compressor - portable.  My tank has rust slurry in it and I need to clean it out.  Is there a recommended method to flush a small air compressor tank?-

How old is it? Have you been draining it daily (when used), or not?

If elderly and it hasn't been drained regularly, buy a new tank, remove this one, drill holes in it so someone else doesn't try to use it as an air tank, and junk it. If that feels overly drastic, get it hydro-tested. Air tank explosions suck...

If not too old or old and regularly drained, you could either not worry about it too much, or try to flush it out by adding water to the tank. If you have any reasonably large openings (doubtful on a small compressor tank) you could drop in some chain to serve as a "scrubbing" device to help free up loose rust as you turn the tank over and slosh it around. This will require removing the compressor from the tank. If (lacking any large ports) all you are doing is adding water and then blowing it out, you can leave the tank upright and just slosh it back and forth a bit before building pressure on the compressor and opening the drain valve to dump the water (by adding water you will be diluting the "rust slurry" from just being the water that condenses out of the air as it's compressed and the rust in the tank to being something like half a tank of water and the same amount of rust, so you might get more rust out.) More rust will form, as there is always water in the air; in most climates, enough to condense out in the tank, unless there is an air dryer between the compressor and the tank.

If you just don't like the look of the rust in your daily draining - get over it, it's normal. While you might be able to reduce it by somehow coating or treating the inside of the tank it's a fair amount of work and expense for not a lot of benefit.
If you are getting rust in your air, use a filter.


Will a galvanized tin roof act as a ground for a magnetic rooftop antenna I just installed a magnetic based antenna on my galvanized tin porch roof. Will the metal roof act as a ground for the antenna? I am unable to attach a ground block to the antenna cable, because the end is fed through a window and connected to another cable, and the connection is lying flat on top of my air conditioner base. Thanks.

I take it that you are talking about a cellular reception antenna. if so, then yes, depending on the specific make of antenna, the design is to ground through the metal to enhance the reception.

The metal acts as a ground-plane , which acts as a secondary antenna, using this technique should vastly improve performance.
The larger the metal surface, the better the performance
The device will work fine with no metal surface, however you should notice a performance degradation on a non-metal surface


Connecting PEX and my existing Boiler Heating System I was thinking of running oxygen barrier PEX under the floor between the joists in a cold room with a crawl space below and then putting rigid foam insulation below to keep the heat in.  I have an existing boiler that is used to supply the hot water radiators.  Can I hook this system up to my existing boiler?

The systems uses a Weil-McLain gas fueled boiler that circulated the water at 140 degrees F.  This boiler used to run 10 large radiators but we remodeled and added an in attic forced air unit and it now only runs 5. The 9 x 15 room already has forced air heat but because it has a crawl space below, three exterior walls, 8 windows, and is located in Minnesota means that that the floor gets very cold in the winter.  I thought I could use one of the empty runs to heat the floor of this room and make it more comfortable.

Given that you are now running only half as many radiators, you might be able to "re-purpose" the surplus to provide hot water for your staple up radiant floor heating.
An important factor to consider is that maximum floor temperature should never exceed 85 degrees Fahrenheit, so you might need to add a mixing valve and a separate circulator pump. Although, (just thinking out loud) I wonder if you could supply the PEX tubing with "less-hot" water being returned to the boiler. Thereby eliminating the need for a mixing valve and separate circulator pump.


How to remove what I think is a screw head caught in a waste disposal I have a waste disposal, and what looks like a screw head, which is jammed in the waste disposal unit (an Insinkerator 55 if it matters).

This means as the machine is turned on, it makes a banging noise as the 'blades' hit it. I'd like to remove this obstacle but it's jammed tight.

The problem is, the angle. As per this image (red X shows where the screw is)

You can see, the sink is at the top and then insinkerator is below, but the angle of the hole means I'm limited to what I can get in. The screw head is fairly flush, I can't really 'grip' it with pliers and when I do, it doesn't really budge.

I have been whacking at it with a chisel and hammer, and it won't move (hoping to snap the metal) !

I've tried using a dremel tool and attempting to 'sand' or 'file' it away, but are there any other options for situations like this (other than replacing the entire unit).

I also don't seem to be able to take the unit apart so it appears as if my only option is from going in from the top!

Had exactly the same problem this morning, thanks to the thread - it made the repair so much easier... the screw was jammed tight just like the original photo above. I went to homedepot got the tool but could not move the screw at first, what I did was reverse the disposal very slowly using the blades and my fingers, after every slight movement I would check to see if the screw had a position where it was loser, and yip after about 3 minutes I found that position- then use the tool and boom the screw was out... thanks again!


How do I repair a small chip in a laminate floor? I had a company come in and clean my carpets recently, and while they were in the house they managed to chip a part of my laminate flooring.

I went down to the local home improvement megamart, and they suggested a putty designed for this purpose, but they didn't have a putty that was close to the color of the floor.  Most of the putty colors were very light compared to the color of the wood.

They've also got some "pens" that I believe are for hiding damage to stained wood, and some of these are considerably darker.  However, the chip is deep enough that it would be pretty noticeable if I just colored over it.

What should I do to repair the floor in such a way that it's the least noticeable afterwards?  Bear in mind that I'm somewhat of a novice, so detailed advice would be appreciated.

That looks like the chip is in the transition piece and not the floor boards.  For the best results, just replace the entire piece. It doesn't look like it matches exactly anyways, so just try to find something very close.  If you know where the floors came from you might get really lucky and end up with the identical part.

It is either glued in place, friction fitted to a track or nailed (this can't determined from the pic).  Either way, you need to carefuly pry it up, being careful not to damage the floor.  Install the new one as-instructed or buy some construction adhesive and glue it back down and put a few phone books on it until it dries.  Make sure to wipe up any excess glue with a damp rag before it dries.  It was likely cut to fit so you will need to cut the new piece.  If you don't have a saw to do this, take a measurement (measure twice, cut once!) with to where you are buying it and see if they will cut it for you.

The other methods you mentioned are suitable alternatives. If the color is matched well, it won't be very noticeable when standing. Crawling, maybe.


Why does my radiator leak if it's not fully opened or closed? I have a hot water (or steam?) radiator that leaks water unless it's completely open or closed.

The side has a valve that can be turned to open or shut the connecting pipe. The other side has a steam vent.

If I fully open the valve, everything works properly, but it gives off way too much heat.

If I open the valve just a tiny bit, it's still too hot, but bearable. However, it will leak from the steam vent (enough to pool up before it can evaporate).

I told the super of my apartment about it, hoping it could be fixed, but he said just to leave it wide open or shut it off.

I've determined I have a single pipe, steam radiator, with a steam vent on the side opposite the heat pipe.

I read bleeding could help, but my radiator does not have a bleed valve, so I turned it off and removed the steam vent instead.

Some water seeped out. Then I turned it on, and lots of water shot out. Convinced this was a steam radiator, I let this continue until it seemed less like warm water and more like scalding hot steam instantly turning to water. When that happened I turn it off.

About two and a half jars worth of water shot out. Quarter for scale.

I then replaced steam valve and turned the radiator back on, and I'm now waiting to see if it will still leak.

However, this did not help at all.

I'm afraid your super is right. The supply valve must either be fully open or fully closed. If it is partially open, condensate cannot properly drain back to the boiler. It will collect in your radiator instead. How much heat is put out is regulated by the size of the vent valve. If the boiler works by central control, meaning the steam goes on and off for the whole building to regulate heat, you can regulate the heat put out by the radiator by getting a thermostatically controlled one pipe steam radiator vent valve, or simply getting a smaller vent valve.


Adding a switch to control a basement light Had an old ceiling light socket in an un-finished basement that had used a pull chain (before it broke). Recently replaced it with a new plain socket, but there is nothing to turn it on and off except unscrewing the bulb. I'd like to add a single pole switch nearby (no more than 10ft or so).

My plan would be to run a single line from the light box, parallel with the floor joists, in flexible conduit, up, over and down to a switch box on a 4x4 post. There is nothing else running to/through the light box as of now, so I'd simply hook it up as shown.

(red being neutral...and the ends would be marked to indicate they are acting as hot)

There wasn't a ground running to the light box, on the old socket, or on the new socket as far as I could tell, would that be a problem at all?

I'm assuming that just leave the wire exposed, without some kind of conduit would be a no no if it's extending down below the joists, correct?

If I wanted to add an outlet at some point, running from the light box, would I simply tie it in to the hot and ground running to the box? And if I added an outlet, would it be a problem not having a ground? (I might just be able to detach the source wire and strip the ground back if there is enough slack)

The switch you plan to add will work fine without a ground.  Do make sure there wasn't one tucked away in the lighting box, or trimmed back.  It is very rare not to have a ground in every cable unless it's a very old house.

If you want to comply with the strictest codes start by ripping out the existing light circuit, then run an all new circuit to the switch first, then to the light.

The conduit is not necessary to run down the wall if it's stapled properly to the inside of the stud cavity.

As for the outlet, you should branch it off of something grounded, or go to the effort of running a new circuit, so that you can have gfci in an unfinished basement space.

Or if it's something you won't use often, or doesn't have a grounding pin, consider those adapters that give you two ungrounded outlets and a light socket from one light socket, and an ungrounded extension cord.  Iirc, there are ones that have pull chains for the light too.


How can I determine which MERV filters would be best for my air handler? I have a Carrier 3.5 ton, 1/2HP air handler (Model Number:fc4bnf042).  I have been using MERV 13 a/c filters for a few years now because my son has allergies.  I recently discovered that the higher MERV filters can cause resistance that can strain the blower.  Does anyone know if there is a simple way of determining whether I am OK with the MERV 13?

One website I found is selling filters in the same range as yours for that model.

Outside of checking with Carrier, though, I can't think of an absolute answer.


How should I get the service entrance cable to my new adjacent panel location? How do I have to run the SER cables from the original hole(where the SER cable goes through the wall) to the side of the new panel?

Can SER cable be exposed or needs to be inside a conduit? Conduit type? AFAIK I can not use EMT, the city inspector says that, and she is not very friendly on providing such information.

Edit/Update:
Here is the entire picture of old and new panel

EDIT about Service cable entrance

I see where there is a cripple wall or something preventing you from fitting the new taller panel where the Zinsco had been.

Well first, I would go back to the drawing board and see if I could find a panel that fits inside the space the old Zinsco is coming out of.  However your first priority is a whole lot of spaces, so I would only bother looking at CH or QO, since they put 40 spaces where other panels only put 30.  In this day and age, you want 40.

If you just can't find a 40 that fits there at sane price, then continue with your original plan.

I presume you've considered laying a piece of plywood atop the pictured joists where the Zinsco was, with the new panel's entry hole lined up perfect with the conduit nipple, and extending the nipple as needed.  I can see where that would create an access problem for one conduit entry at the bottom.  Okay.

I consider the idea of using exposed flexible cable to be beneath discussion.  It is on the wrong side of the main breaker, if it got hit with something, nothing would stop the arc fire.  The bend would be freakish and very, very hard. You need XHHW single conductors just to make this DIY doable, and that needs conduit.

But that's no big.

Oh? She doesn't want EMT? Alrighty then... use RIGID.  Realistically, you will need a conduit body to turn that corner anyway. That leaves only about 3 inches to go with actual conduit.  Rigid is pricey stuff, but that doesn't matter for 3 inches.

When you tear out that ZINSCO panel, there will be a "pipe nut" that you unwind with a hammer and screwdriver.  Once the panel is out, underneath that is probably a Rigid pipe nipple (a nipple is a short pipe) with pipe threads.  Test fit the conduit body and see how much distance you need.  You either replace that nipple with a longer one, or add a coupler and a short nipple to reach the conduit body, depending on what is practicable.

With Rigid conduit, you go to a competent hardware store who cuts and threads pipe (and shoplifters), and buy the right length and have them thread it.

Now, the only other risk is that the conduit body is so wide that it forces the new panel to the left.  Could be.  If that knocks it off the joists, get a sheet of 3/4” plywood about 33.5" (or wide enough to span 3 joists and 2 spaces) x the height of the new panel + 6”.

Then, you will need to account for the thickness of the plywood in the above nipple.  So test fit everything first!

Then, you use appropriate sized XHHW wire.  If the price of copper wire gives you pause, use aluminum wire 2 sizes larger.  All 100A+ terminals are designed for aluminum wire and have aluminum lugs.

Remember, this is a whole domicile service, so you get the 83% favorable derate from NEC 310.15B7.


What material should I use to hide a duct running just above the floor in a closet? I have an 8-inch HVAC duct running along the back corner of a closet (4 feet wide) at ground level. I assume a good way to hide it would be to build a frame of 2x4s. However, while drywall would work on the side, would it be strong enough along the top edge? Worried someone may stand on it one day and break through. Is plywood a better choice? Or are there fire-proofing considerations?

I have used 1x2’s as the frame around ducts and plywood to make a shoe rack.
I usually use Sheetrock/ drywall to close in ceiling mounted ducts. No one knew or will know it is a duct if you disguise it and make it wide enough it become a feature.
I am sure you could use Sheetrock. make sure to have a shelf over it and there is less chance someone would step on it


How to deal with ants in wall I have a pretty bad ant infestation.  I think the little critters are Argentine ants.  I've used a couple of bottles of Terro (I usually put down about a quarter bottle at a time).  It does slow them down, but they come right back not after not too long.

I have been thinking about using an aerosol insecticide.  The stuff I have has imiprothrin and cypermethrin as active ingredients.  The are supposed to be good enough that I can just spray on their trails, and they'll die if they walk over the sprayed areas.

The problem is the location of the trail.  They're coming out from a space between the baseboard heater and the wall's outer finish.

Can I spray the baseboard heater?  I'm not worried about fires, but I'd really hate for the insecticide to start outgassing when the heaters get turned on this winter.

You should lay a bait down.  I recommend Advion, which is a product from DuPont or MaxForce, which uses fipronil.  You can do a search on Amazon or a similar site for "Advion ant" or "MaxForce ant". The bait comes in a plunger that you can use to apply in small places.  Find out where they are trailing and put a few drops down.  You can put the drops on paper if you are worried about your finish.  Every day (or couple of hours if you have a bad infestation) check to see if the bait's gone and reapply.  It may take a couple of weeks to kill them all.

As far as Terro goes, I haven't had much luck with it either.  The attractant in Terro's all sugar-based from my understanding.  The ants may be feeding on Protein now.


Painting the old utility stairs to the basement So the stairs to my basement(like most others) are not made of any nice lumber. It’s just 2x10s for treads and something like 1x6 for risers. No rounded over edge of the treads or anything. Where the treads meet the stringers some pretty significant gaps were there and so someone a long time ago packed mortar in the gaps and the painted them over with the old lead based paint. I finished my basement and the last thing I want to do is paint the steps. Being that they were just made out of some kind of pine lumber they have a pretty rough looking surface from the knots and various gouges over the years. I want to essentially skim coat the treads with thin set mortar so I have a nice smooth surface to paint. Anyone every heard of doing that and if so does it hold adhesion under the weight of constant footsteps up and down?

In my opinion, that's the wrong approach. Cement and mortar don't do well in places that move, and stairs tend to move.

I've restored several sets of old basement stairs in my homes, and new lumber is your best bet. I've gone with stained pine, which is beautiful but a bit soft. If you're going to paint, consider bullnose particle board.

By rebuilding with 1x8 pine and your choice of tread you eliminate those gaps, remove any squeaks (by using construction adhesive on all joints), and leave a very nice base for some good floor paint or stain and urethane.


How can I fix this furnace filter slot to prevent filters bending? I noticed a problem with my furnace filter.  In the vertical slot where it gets installed, there is a channel along the bottom but not along the top.  As a result, the top corner of the filter furthest away from the opening will bend toward the blower motor and allow air to rush past the filter.  How can I fix that without taking apart the whole intake duct?

Dumb idea #1: Put a series of machine screws along the duct opposite of the filter slot.  The filter should push against them when air is flowing and no longer be able to bend.  The bad part: Would then be even more of PITA to line up the filter and get it in.

Assuming you can find a channel at one of the big box stores you can slide the channel in and maybe screw it in all the way at the end so the screws don't interfere with the filter. In fact it seems like you don't even need a piece of channel. A piece bent like an L should work. When you screw it in offset it so the top of the L is not above the top of the filter. Attached is a drawing.


Main outdoor breaker is ONLY 100 AMP but total of Breakers AMP on internal panel is 165 AMPs. Main outdoor breaker is ONLY 100 AMP but total of Breakers AMP on internal panel is 165 AMPs.  From what I have read so far this still ok.  I could have Subpanels/Feeder Panels down stream from the main breaker requesting more output but if the Main is unable to handle it then it should "flip off"  correct?

Synopsis: The sum of all the branch circuit breakers is a meaningless number.

The main breaker will "trip", or "flip off" as you say, when the current (amperage) load well exceeds it's rating for a predetermined amount of time. Meaning a breaker does not trip when the load is 1 or 2 more than the rating. The "continuous load" on the panel should not exceed 80%. In a residential application this is a hard number to pin down though.

As to your sub-panel question, a load calculation is the only accurate way to tell if your service is adequate to support any new loads on the service.


Roofing nails through 95 year old tongue/groove soffits I just had my 95 year old house painted and re-roofed. Is this acceptable? I’ve read that the nails need to be so long- but this is crazy! My shingles aren’t 95 years old- and didn’t have this problem when it was last reroofed.  So sad for these little pieces of history.
What can be done?

Depending on how far up your roof is, if you paint it you probably won't notice the nails penetrating.

This is fairly common when there is no decorative soffit and just the underside of non plywood sheathing.  Yours did look surprisingly good before. I've never seen one that didn't end up looking like a bed of nails but the ones I see have typically been painted since the nails went in and while visible have a similar character to the un-sanded, partially peeled paint that was painted overtop on a lot of your woodwork (old, looking decent but missing finer detailing/workmanship).


Efficient way to test smoke detectors I just got done wiring boxes for my hardwired smoke detector system and am about to start installing detectors.  When testing in the end, I heard they sell some test aerosol spray which is the officially (I guess) endorsed way of doing it.

Just out of curiosity, I was wondering if there are alternative safe (as to not burn something or the whole house down) and efficient ways of doing it.  I had done it before by burning a piece of paper near one but I'm thinking there are better ways.

The sprays are the official way to do it.  I don't really like the chemicals in them, but I do use them.

I've also used a candle, which I snuff out below the detector.  This is safer than the paper and produces more reliable smoke.


How do I join my horizontal slat fence with my neighbor's fence (vertical fence) I am thinking about building a horizontal fence to close the open space left by the previous owner to the left of my garage.
How do I join my fence with the exiting fence of my neighbor. Do I have to build my own post next to the one behind the blue garbage bin?

Edit: I am not worried about the legal implications and it does not matter on whose property is the fence. I am just looking for a technical solution

The picture below shows the intended functionality

Update: I looked at that post and it was set in concrete and it is rotten as it is the on to the left side on my neighbor's property. There is another one rotten just behind the small tree at the end of the area that I am trying to cover There is no way that I am going to attach my gate to that post unless I decide to replace it and to split the costs with my neighbor. However doing that will complicate the solution. I am planning on using one of these:

for the removable central post. I would like to use the same for all the posts but I am not sure if this is advisable. This will be a horizontal fence, made of cedar boards cut of 1x(2" or 3" or 4" or 6")x 8" to match my needs and to build the design that I am planning to use

Before you start, talk to your neighbor first, get a feel for any concerns if any they have. Then inspect the post to see if it would hold a section of fence. Then go to it.

EDIT: Ok lets try a different approach, dose your property line split the post, (red line), or meets it (green line)?

This will make a difference. I would also consider placing a stationary panel first because the swing of you gate would be hitting the curb on the driveway.


What could be causing water to back up into my bathroom basin? out of the blue, water just started pumping out of my bathroom basin drain flowing over the counter top onto the floor - nothing had been turned - this is a highrise condo I'm on the 3rd floor - maintenance says there must be a clog in my pipe that connects to the building pipe but how could that much water all of a sudden come out of my drain ? I'm thinking the building pipe is clogged.

You say you are on the third floor but do not say whether or not there are floors above you. If there are, and this began while you were not running water, then I agree that this is probably a building issue rather than a local clog.


How do you clean up tung oil that has dried on a concrete porch A neighbor's granddaughter got tung oil on her concrete porch while staining the front door. Unfortunately, it's been a few months now and I'm trying to help her find a way to remove the stain.
I tried paint thinner and mineral spirits which is what is recommended on the can for cleanup - but no dice. Yesterday I got some concrete and driveway degreaser, scrubbed it and then power washed it. Nothing so far has worked.
I suggested she might want to buy a nice outdoor carpet to put over it.
Any ideas on what might work?

Caustic soda.
Sprinkle on and dampen to a paste, cover with newspaper and plastic sheeting.
allow to sit several days, sweep off, scrub,  and rinse off with plenty of water.
Danger: corrosive: Keep away from aluminium, Wear water-proof gloves and eye protection.  Wash with water without delay if you get any on you.


What can I do about my kitchen sink that has clogged suddenly and completely? I had no problem with my double kitchen sink ever since getting Nu-Flo in our 1970s pipes, and their installers told me the kitchen drain had been installed going up instead of down so it caused the sink to back up. They fixed it and my sink drains fine ever since.
Yesterday I was rinsing out a small milk frother and trying to remove small bits of carmelization from it on the right sink, so the water was mostly clear. Suddenly the water backed up. I plunged that side while holding a stopper over the left side. It didn't have much effect. I used a product called Plumb Away that supposedly whooshes air at high pressure. I could hear and feel some movement on the stopper but saw little to no effect on the drain.
Plumb Away says if you use it three times with no effect, call a plumber. The third time I used it, water came spurting out of the thing next to the faucet, all over me, but still the water didn't budge. I don't want to call my landlord because if they will try to charge me for the plumber.
Overnight the standing water went down very little. It's strange that the drain went from fine to completely clogged in one instant and I wasn't pouring anything cloggy down. Also I would say I'm a light user of the sink because I don't cook a lot, I don't pour grease down it or anything like that.
I called my downstairs neighbor and she said her sink backs up when she uses the disposal. I did run the disposal and the left side went down immediately but no effect on the right side. I didn't know this but apparently the disposal only is for one side? (I hardly use the thing honestly, never had one before so not accustomed to using it.)
Does this sound typical? Do you think it can be fixed by something like Drano Gel?
Edit: The thing next to the sink looks like a sprayer would go there but there's nothing there. I have no clue what it is, and when I tried to find imgs online I couldn't find anything similar so I had to get up (ugh) and take a pic, sorry for the dirtiness of it:

No probs with the other drains. I called one of my downstairs neighbors and she said she has ongoing probs with her kitchen sink backing up when she runs the garbage disposal. I assume we are on a sewer system.
Edit2: I tried Drano Gel, followed the directions for the tough clog and used the whole bottle for 30 minutes, and it's still clogged. I guess I gotta call the ogre.

Usually it is illegal for the landlord to charge for building repairs.  The only time a landlord should be able to charge is when the damage is not from normal wear and tear (like dumping a pot of rice down the garbage disposal).

It's hard to guess what is causing the blockage but bet it is related to the Nu-Flo coating de-laminating and clogging the drain.  It is best to notify the landlord to have a plumber come out to auger the line.

The item on your sink is an 'air gap' to connect the dishwasher to the disposal.  The air gap prevents the garbage disposal from black flowing into the dishwasher.


A/C units sweating in the attic I have 2 Heil 19 SEAR units that are sweating tons of water in the pan. They are V speed units that can regulate the humidity in the house to 50 t0 55. The house is a foam house which has been sealed and resealed after a smoke test.
Humidity in the attic is 72 with a temp of 76. I am told that this is too close to the dew point and need to plug the holes. We plugged a 4" bath vent to the outside that had been disconnected and small leaks around a dormer. The house is on the Gulf coast.  I still have sweating units and some ducts that are moist.
There are returns holes in the plenum and a 4" discharge in the attic. The holes and discharge were attempts to solve the humidity issues.They helped some but did not correct the problem.  Any suggestions?

Sweating or normal condensate is a byproduct of air conditioning. Dripping in the pan and will continue to do so until the humidity is 20-30 points lower then it will slow but continue to drip (that’s why there is a pan to catch the water or condensate)
Once the water is caught it can be pumped or piped out of the home.
If you have sweating on the outside of the unit you are lucky your pan catches it. Insulating that metal surface can reduce or even eliminate sheet metal sweating when sealed with insulation.
So sealing is a start but insulating the ductwork Will be needed because as long as there is cold metal in a high humid area it will sweat.
If you have a glass of ice water is it sweating? Your metal parts are the same.


Is it safe to "cap" a disconnected doorbell wire using electrical tape? I recently decided to disconnect my doorbell to stop it from waking up the family. I removed the doorbell from the outside of the house and disconnected one of the two pairs of wires that were connected to it (two pairs of two wires, each pair connected to one screw). This disabled the doorbell just fine, but I am worried about the way I "capped" the live wire using electrical tape. Since the wire nuts I have don't fit inside the doorbell this was the best I could come up with. Once wrapped in electrical tape, I tucked the wire back into the doorbell casing, screwed the one screw back in, and reattached the whole thing to the house. Is this safe? Everything I have found online mentions that it is safe due to the wire being low voltage. This is a new doorbell on a new home, if that makes a difference.

Reference

  All doorbells have a transformer that changes 120 volts of household
  electricity into 24 volts of electricity.or less. This low voltage is
  not dangerous and wrapping the wires that come off the transformer
  with electrical tape is a safe way to seal the wires. Tiny wire nuts
  can be used for the same purpose.

Edit

I am in the United States, MN specifically.

Doorbells in Europe use mains voltage.  The far better way to do this is to disable the supply transformer or other voltage source, or disconnect the doorbell at the transformer if it shares the transformer with the furnace/thermostat.

For that matter, nothing keeps you from putting the doorbell transformer or other power source onto a cord-and-plug connection, and then stick a lamp timer into the socket.  Now the doorbell will only function the hours you specify.    You can put a sign on the doorbell to this effect.


How should the disposal be wired without running neutral to ground? We had an electrician move outlets and switches in our kitchen and it seems like some stuff wasn't done right or shortcuts taken. Here is our situation. The outlet is half hot and other is on a switch for the disposal. You can see that he runs a neutral to the ground.

This box has two switches, one for the disposal which is on the left. The middle switch is the kitchen sink light, which is on the same circuit. The outlet is completely on a different circuit. You can see that he is running a neutral to a ground here too.

Here is my poor electrical diagram too, even though it probably doesn't make sense.

So, my question is how does this need to be cleaned up to make it safe and correct?

2 circuits, 1 receptacle, 0 problems

The extra cable running to the problem receptacle is indeed your saving grace, as it provides an always-hot and neutral to go with the switched hot and neutral from the switched circuit.

So, to fix this, you need to:

Make sure both circuits feeding the receptacle-box (the disposal circuit and the dishwasher circuit) are off.
Take the two white wires in the switch box that are nutted to not-white-wires (the one going to ground and the other going to the bundle of hots), unnut them from where they were nutted, and nut them to each other instead.  This provides a neutral to the switched side of the receptacle.
Remove the nutted together bundle of white and bare wires in the receptacle box.
Pull enough cable from the cable lurking in the back of the box into the box and strip its jacket and wires back so you can use it.
Make sure the tabs on both sides of the receptacle device are broken off.
Nut the two bare wires in the receptacle box together and to a pigtail going to the receptacle's ground screw.
Wire the white wires to the silver screws on the receptacle and the corresponding black wires to the corresponding brass screws on the receptacle.
Button everything back up and turn both circuits back on.
Enjoy your new half-switched receptacle!


How can I stop my shower doors from hitting one another and making an awful noise? I have glass doors in the shower of my master bathroom and when I open and close the doors the screws hold the panes of glass to the runners are bumping into one another and making an awful noise.  I have the similar doors in the guest bathroom that are quiet as a mouse so I know there is a fixable problem, I'm just not sure what the problem is or how to fix it.

Please take a look at this video to see the problem in action:

Please take a look at this photo album to see the pieces involved:

Click for larger view

Does anyone have any idea what might be causing this problem?  Assuming it is the bottom piece in the photos, does anyone know what that piece is called and/or where I can purchase a replacement?

Hard to tell. I would slowly operate the doors a few times and try to see where something might be contacting another piece. I don't think the top brackets are touching each other unless somehow the screws had losened. The top rail should keep the apart.

The spacer on the bottom I think might be the issue. The outside door looks pretty low. The top rail might have sagged a little or was not installed level and the outside door might be hitting it as it passed over it. Or possibly some sort of deposits have built up on the bottom.

You should be able to raise the outside door by removing it and repositioning the screws in the bracket. It differs by model but I haven't seen a set of doors that don't have some adjustment. When the doors are removed also make sure that bottom plastic spacer is clean and properly installed.

If you do this, wear shoes, a long sleeve shirt, gloves and safety glasses in case the glass breaks.


Is it possible to control the speed of the fan on my central A/C unit? I have one of those medium sized AC-units (don't know the model name at the moment) and a very basic Honeywell thermostat that the installers put in when the house was built.

However, there doesn't seem to be much options.  I can only turn the fan on or off, AC on or off, set the schedule, and the desired temp.

Is there a way to control the fan speed (It's quite loud and I'm planning on renting the basement out... with the AC unit right next to the basement window) like those portable AC units? Is this dependent on the thermostat or the AC unit itself?

There are numerous instructional videos on how to change the air speed CFM on an airhandler, so YES.  Rather than a switch, it is achieved by the wiring.  There will be a chart and a wiring diagram on the unit that will direct you.  One speed of air does not match all configurations.  A specific CFM on a 3 ton unit with a single trunk line feeding a shotgun house might not be the same as a 4 ton unit with a different duct set up, yet the air handler itself might be the same.


Can an entry door unit with sidelight be disassembled and reversed? My front door has this configuration:

I'd like to swap the door with the side panel to obtain this configuration (without flipping anything):

Would that be feasible?
By feasible, I mean simple enough to be overall cheaper than replacing everything :)

The images above refer to configuration.
The actual doorset I have installed is similar (except the panel and door are swapped) to the following one:

The door swings inside, is fairly recent and I believe it is PVC. The door and side panel look like two independent modules, with the junction covered by a wooden slab held in place by some visible sealant. That's why I was wondering whether it's possible.

More precisely, here are two pictures of the junction in the middle. This is the bottom part, where the door set meets the floor, taken from the inside. These images depict the actual door in question.

Thanks!

If the two units are indeed modular as you've described, then you can probably make this work. Some caveats:

The two units are obviously connected somehow. This is probably done with a combination of mechanical fasteners (screws, brackets) and sealant. You'll need to figure out how to separate them without damaging the other seals and joints, and then you'll need to reconnect them using metal plates, etc., along with sealant.
There may have been a weatherseal/mounting flange around the outside of the assembly when it was installed. This would now be behind the stucco finish on the building, and you'd have to cut it away without damaging your stucco.
When you reinstall you'll need to weatherproof without the benefit of the flanges. Strategically placed, high quality caulk could do the job, possibly backed by rope caulk or other filler. I doubt that you'll have room for spray foam insulation, but you could use that if you do. I'd use urethane caulk on the outside. It's extremely sticky and durable.
I'm not sure what the threshold situation will look like. That's an area of particular concern, since leaks can eventually damage the floor system framing as well as the finished floor. I'd have a plan before I begin.

Now if you have the means to re-work the stucco, you can cut it back a few inches and work the project as if it was new construction. That would be ideal, but obviously much more expensive.

Original answer:

Not really. It was constructed as a unit, and reversing it would require all the hardware mounting locations to be reversed as well as the frame members. It would be a massive operation and you'd probably lose both structural integrity and weather sealing in the process.


How do I fix gaps around my lean-to greenhouse? Added this to gardening and was advised to post here.

I got my greenhouse and didn’t account for the sloping away of the wall it was to go against. Meaning a small gap at the bottom becomes 4” at the top.  I can’t push it into the wall as it warps the greenhouse and can’t leave the huge gap.
Is there a way of deal with this?

I was thinking of maybe
 - some type of structure around it then fill with expanding foam then remove the structure.
- some mesh then plaster it

Make a wood frame with the required taper.

This may also help with sealing to the surface of the wall.


Access to LED downlight drivers Helping my son build a house and he went with Lithonia WF4 LED lighting (pic attached).   I know all connections need to be "permanently accessible" but mounting these drivers and connection in the joists with only a 4" opening for the removable downlight as "access" doesn't seem reasonable access. Is there a better approach?

Access to the wiring connections of any can light is based on pulling the light out of the hole, then accessing the connections though that hole.  In this case, the wiring box can be pulled all the way out of the hole so you're in better shape than some situations.

With a good brand name like Lithonia, this are sure to be UL listed which means they should conform to common building codes and have been tested for safety.


What are the codes for electrical wiring in attics? What is the typical code for wiring in attics? I understand these vary but what's best practice?

Can you just have electrical wires exposed with all the junctions, in junction boxes, provided all the exposed wiring is anchored to the wood studs?  What about insulation that comes in contact with the wiring? Or does the wiring have to be an aluminum armor?

"Can you just have electrical wires exposed with all the junctions, in junction boxes, provided all the exposed wiring is anchored to the wood studs? What about insulation that comes in contact with the wiring? Or does the wiring have to be an aluminum armor?"

Wiring should be stapled to the wood studs and have splices in accessible junction boxes. Check local electrical codes for specific requirements.

There are no issues with modern wiring touching insulation. It touches insulation all the time in your walls.

I guess I need to cover more bases: Don't use knob and tube. ever.


Light fixture, power source and range vent fan & light wired together? I removed a light fixture to find this wiring in box.  4 sets of 12/2 wires coming into ceiling box for light fixture.  One is power, one goes to switch for light fixture.  Other two go to an exhaust vent over stove.  There is a light switch and fan switch on vent.  When looking closer at wiring, I noticed that there was a ground wire with a green wire nut that was 'on' the wire.  I.E. someone put a hole in end of wire nut, and ran wire through wire nut. I don't believe this ground wire was attached to any other wires, seemed loose in box when I pulled on it.  Ground wire comes from either vent light or vent fan. Additionally, light fixture white wire is wired together with black wires from power source and vent light and fan.  Then when checking switch, there is only the white wire attached, black wire has been twisted around the white wire.  After taking light fixture down, I lost power to the vent fan and light.  Never seen anything like this before.

The green wire nut with the hole in the tip is normal.  Green wire nuts are the same size as red, except they have a hole in the tip.  That's why they're color coded green, to tell you that.  And they're for exactly that use.

All ground wires should be connected to each other, and also to any appliances or devices and also the metal box if metal.

The switch is what's called a switch loop.  It's an older style one with /2 cable (black, white) and no red.   In a switch loop, the white wire should be used as always-hot and tied in with the blacks.  The white wire is chosen to be always-hot so it's more obvious when you're checking it with a voltage tester.   It should also be marked with tape to indicate the white wire is a hot, this step is often overlooked.

It sounds like the other cables in the box carry onward power to other devices, e.g. the hood.

It would help to have photos of what is going on in those boxes.


How can I stop new solid oak floor from squeaking? really hope someone here can come up with an idea to get me out of this one:

I recently laid a new floor in my dining room, it's solid oak and it actually looks quite good considering I put it down!

Only problem is, it's quite creaky when you walk on it.

I asked a few friends (one contractor builder, the rest just amateur DIY'ers like me) about the best way to lay it, and they all said to install it as a "floating" floor. So I went out and bought a load of fixing clips, and as I went along, I put one clip about every 3 foot from each other between each strip of flooring.

Now I'm not so sure if that was needed, as I was laying it onto existing floorboards.

I'm pretty sure it's the fixing clips which are causing the floor to creak, but I don't think I'm going to be able to lift it all up (without damaging it all), as the clips are holding it all together pretty tight. Any ideas on how I can stop the creaking?

For a non-floating floor, you would stand on the squeaky part while someone screwed in through the sub-floor in to the squeaky part of the floor.

I've never dealt with floating floors before, but I assume this is not an option because the movement might cause cracks?


What are some good downspout options for a brick house? I need to replace the gutters and downspouts on my house, and I'd like to know the best approach.

The house is 100 year-old clay brick house. The old gutters were aluminum and used downspouts that sat on hooks embedded in the brick (with a series of notches on the back of the downspout), and were held against the house by pressure from the gutters at the top and being sleeved into pipes that run to the sanitary sewer main at the moment (we appear to be grandfathered into the system, but yes I know that's bad).

The gutters were pulled off and damaged by a snow storm, but most of the downspout parts are intact. One of the pipes that runs to the sewer is collapsed so we need to use a different system to remove the water from the base of the house at that corner.  I'd rather NOT put new holes in the brick if I don't have to, but all the local home improvement stores seem to see plastic gutter systems that use different mounts (brackets that wrap around the downspout to hold them against the house).

If I look around are there likely to be places that might have parts for aluminum gutters? Is trying to rebuild a system like we had the best idea or should I replace with something different?  If I did switch the gutters, is there a gutter system out there that might work with my old brackets so that I don't have to put new holes in the walls?

Is there some particular reason not to put new holes in the bricks? My first inclination is to just drill new holes, and secure the spouts properly - after all, they did come off during a snow storm.

Do you have pictures of the existing mounts? Perhaps there is a way to retrofit something onto the existing hooks but still use a modern downspout.


How long should it take concrete to fully cure? I have just had a backflow valve installed in the basement. The man had to chip away some of the concrete, he then put new cement down. He also had to do some work outside around the foundation, he installed a pvc pipe as a weeping tile. This was Tuesday morning the 26th June 2014.

We had a lot of rain that day. last night I noticed there was a lot of moisture on the cement in the basement. How long before we have to wait for it to cure and is this normal. We do get lots of humidity in the house. I forgot to mention this was put on top of mud. This is in Canada.

Concrete will never fully cure; it continually hardens forever, although for all practical purposes, it reaches a point where further hardening will be so slow as to unnoticeable.

Unless the mix has retarder (or some cement replacement material) in it, it will generally be hard enough to walk on in less than 24 hours.

Mixes are usually specified with a design strength - the compressive strength that the concrete will reach in a period of time, typically 28 days. As a general rule, at 7 days it will have reached around two thirds to three quarters of the design strength.

Don't worry about the water on the new concrete - it will help the concrete cure if it is kept damp after the initial set. The early stages of concrete curing is the hydration of the cement in the concrete.


How do I ensure the bathroom door stays open unless someone is inside? When my windows are open, the wind can slam the bathroom door shut.  I don't want this to happen when my cat is in the doorway (dead cat), or inside the bathroom with no one home (locked in with nowhere to pee).  I want the door fully closeable when someone is using the bathroom though.

Right now I have a book as a door stop, but it is easy to forget to put it back in place.  Anything else that needs to be enabled manually (like those door stop things that swing down) is also no good.

I want a way to keep the door ajar by at least a few inches unless someone is inside and manually overrides it, but then after they open the door it resets and failsafe holds it open again.  I'm imagining some kind of spring-loaded arm with a rubber foot attached to the door, but there might be a no-brainer solution I'm not thinking of.

In other words, a person can disengage the stop in order to close the door, but as soon as they open the door enough to leave the room, the stop is engaged again automatically.

What about a magnetic door stop combined with a stay open spring hinge?


Conduit fill - number of circuits .vs. number of branches I think I get this one, but just to verify or clarify... (USA NEC)

When running multiple circuits (different breakers) in a single conduit, you have to derate after (is it 4?) sharing the one conduit.

But, if a single circuit (one breaker) is going to a bunch of light switches, and then the switched lines from those switches (and likely the hot line going on to other switches, LED lights do wonders for number of lights on a circuit) are sharing a conduit before they reach a junction box where they split off to the individual light strings, that's still one circuit (but more wires for the fill calculation, of course) from the "do not need to derate the wires in conduit" view?

I've seen too much rodent damage to be happy using NM cables...

If a group of wires, together, are splitting power from one circuit, such that they together could not exceed the breaker rating without a trip -- then those wires together count as 1 wire for this purpose.

Let's suppose you have box A and box B.  Supply comes in to box A. B has a GFCI deadfront and a bunch of switches, protected by the GFCI.

Supply hot goes from A to B.
Supply neutral goes from A to B, to supply the GFCI.
Five separate protected-switched-hot wires double back from B through A onward to their destinations.
Protected neutral doubles back from B to A, where it splits to feed each switched load.

This situation is annoying, because we must haul neutral from A to B and back again because of the GFCI.  At 15A draw, how many wires "count" for derate?

supply hot is carrying 15A to the GFCI
supply neutral is carrying 15A to the GFCI
protected neutral is carrying 15A to the loads
Five protected switched hots, totaling 15A.

So four "wires" for derate, which in a 120/240 split-phase context we can simply count as 2 "circuits". The actual limit is 9 wires, but it's impossible to have an odd number of wires in split-phase.

If it wasn't for the GFCI, neutral could splice at box A and need only carry smart-switch loads A-B, which means it would be splitting the 15A with the switched hots, and we would only count 1 circuit.


How to drill a hole in plexiglass (acrylic sheet)? What kind of bit should I use to drill a 1/2" hole into acrylic glass (plexiglass)? The local hardware store does not have a 1/2" hole saw - which was my first inclination. I am now considering these options in the following order:

Spade bit
Forstner bit
1/2" straight drill bit
Step-up from small (3/16") to 1/2" straight bit
Knock-out/Step-up bit
1/2" Diamond plug cutters (expensive)

I'm thinking the spade bit may work but will leave a rough surface (which I can sand) and will give me less control than a forstner bit. Starting with small straight bits and stepping-up to 1/2" seems safe but time consuming.

You do not specify thickness, so I'll take a guess at 1/4" or thinner.

The problem with drilling plastic is that conventional bits will "catch" on the plastic, pulling the bit into the hole with more force than desired, typically cracking the plastic being drilled.

Using step-up method to drill the hole will not eliminate this problem.

Lacking the aforementioned hole saw, the spade bit is a better choice. I have Forstner bits but have not considered trying one on plexiglass. If you have a drill press and the increased control it offers, you may have good luck taking small bites with the forstner. The cutting edge of a forstner bit is more like the edge of a plane and may also dig in too quickly otherwise.

Drill bits designed for plastic have a much sharper angle. A set I recently purchased has an abrasive material on the cutting surface as well as a subdued cutting angle, effectively abrading the plastic and lifting it to the surface.

I overlooked your option of a step drill which is the best of the list. Each progressive cutting edge will not gouge into the plastic as much as any of the other available choices. Again, a drill press improves your chances of a good result.


What could be the sources of humidity that build up in a house in an arid environment? Outside RH: 10%; Inside RH: 40% + We open our window at night at the temps get down to 70F @20% RH.   The temp in the house drops to 75F and the RH is 33%.    We close our windows when we go to work.

When mid day comes, outside, the temp is 95F and the RH is 10%.  Inside the temp is 76F and  RH is 40%.  How is this possible?

we have no water leaking into the house... with water off... usage is 0.
Cement slab.
Nobody is home.  We have a couple dogs but they can't contribute that much water.
There is a temperature difference in the house one side is 74F and another side of the house is 78F.
We are waiting on a manual J to be completed, the guy thinks our AC is oversized.  But that explains why moisture isn't leaving.  But it doesn't explain where the moisture came from to begin with.
We had a pressure test done on the house... -0.1 pascals.  So we are in good shape there.
It seems to me the only way water could get in, if no leaks, is condensation some where.  The air handler is in the attic, attic get hot during the day...

In most building calculations... if we recycled 60% or our air and used 40% from outside at 95F at 10% humidity, we would have to add a quart of water every hour to the air to MAINTAIN 40% RH.  THIS IS NUTS!!!!  So much for the idea that we are breathing air through a leak... as a problem.

https://www.lenntech.com/calculators/humidity/relative-humidity.htm

I saw a question VERY similar to this answered on This Old House. Here is the
link to the video that explained why it happened and how to fix it. Hope it helps.


using two outlets as extension cord I'm helping a friend build a cabin and we have a generator. I was wondering if I could wire an outlet on the outside of the cabin and another inside. The outside outlet would be for power in and the one inside for power back out, basically utilizing the two outlets as an "extension cable". Obviously we could just run a cable in the house but that doesn't look nearly as good. I'm also thinking of splitting off the wire and running a single light. Does this sounds plausible?

Yes, and I've done this myself.

But not two outlets.  The generator side one is an inlet.

(These also come in a form-factor that is the same as an outlet).

From the inlet, you use in-the-wall wiring to go to as many outlets and lights as makes sense for a single circuit.

If you want 2 circuits, you can have 2 inlets, and plug each one into a different pole on the generator.

If you want >=2 circuits, you can have 1 inlet that is 20/30A 120/240V such as a NEMA 14-20 or 14-30, and then feed that into a service panel in the house.  From there you can branch off as many circuits as you please!

PS. Once you get sick of hauling in fuel and maintaining the generator, look into solar+battery systems, and wire as many loads as possible to be able to work on low voltage DC.  Lighting at the very least. LED lighting is your friend.


What options are available for improving the appearance of a concrete porch? We have been looking to do something with our entrance patio flooring. We have some options to have it re-layered with concrete, but we would like something that is better looking and have considered tiling.
Is tiling a good option or are there other alternatives - we are worries about the "slip factor" with tiles, especially with snow/ice.
Is there a specific type of tile cement that must be used for outside?
I know this may be subjective, but just looking for ideas where some have had success.

Another option would be to apply stone veneer to the faces and top of the steps, making it look like stone steps. I've considered doing that with mine.


Shower stall leaking water in the corner My master shower is leaking water at the corner. I have tried to fix it myself one month ago. It only worked for 3 weeks then start leaking again. Should I find shower repair company to redo the stall? or should I just recaulk myself? I feel recaulk might not resolve the root issue. Any advice is appreciated. Thanks in advance

highlighted is the leaking area

I remove the grout which is detached from the stall

This is after I put new grout and I also put sealant on the new grout

Old grout is detached from the stall.

In your third picture there is still a small crack right next to the door track. That corner will do a great job of catching water and letting seep down the wall. Caulk is better to use when changing plane. The caulk on the floor is starting to separate.


Outdoor service panel replacement I want to replace my current service entrance panel with a newer 200A unit.

My question is about how to route the wires from the meter and from the house into the new box.  All the boxes that meet my requirements seem to have knock-outs on the bottom and bottom side only.   I can certainly use a side knockout for the wires from the meter but can I create a hole in the back of the box for the house wires?

I am aware of the height limit to the main breaker and should be good there.  Also, does the number of wires coming through the wall look up to code?  About half the wires come from below so I thought I could add a junction box inside then run THWN wires up through conduits to reduce the number of wires going through the one bushing but if I don't have to do that I guess I'd rather not.

In short, if you were going to replace this box how would you proceed?   Thanks!

You can cut a hole through the back, with a nipple less than 24" long you can fill it to 60%, it's hard to tell from the photo what the fill is, in the past with exterior boxes I have punched 2-3 holes installed bushings and run my wiring from a gutter where I spliced it to some thhn/ thwn and ran that outside. In my last county the inspector felt it was safer not to splice in the gutter and to run the romex into the outside service panel, I would check with your local inspector as they may allow the romex into the service panel (2 out of 3 counties allow this to a nema 3R service panel in my area). The panel must be mounted on the dwelling so the wires directly enter the home.


Induction cooktop connection I have a new induction cooktop Bosch PIF645BB1E rated at 7.4 kW. According to its documentation it should be connected with 5 wires (2 phases, 2 neutrals and 1 PE wire). From a former flat renter I have a power outlet with 5 dedicated 2.5 mm2 wires (3 phases, 1 neutral wire and 1 PE wire). I think that I can connect 2 phases to 2 phases, PE wire to PE wire and 2 neutrals to just 1 neutral wire, but I am not sure that just one 2.5 mm2 neutral wire is enough in this case. Is it OK to connect it like this or I need thicker wires for this cooktop?

Thank you for your answers!

Edit: Sorry, I forgot to mention that I live in Germany and voltage is 230/400 V. Also I attached photos of back side of the cooktop with connection diagrams and photo of my power outlet.

What you've described is the correct way to do this.

As the currents in the two phase wires are fed from different phases, they do not add together fully, and so the neutral will not be overloaded.


How often should a sump pump cycle? Not sure how often a sump should cycle. I have a battery backup installed in case of a failure and it has adequate flow to keep up. The pump runs for 10-15 seconds about every minute after a rain. In the picture you can see how much water is flowing in to the pit id say the rate is equivalent to a sink facuet at 1/2 to 3/4 open.

I did replace the check valve as i read that could cause it but the water isnt coming back in from the discharge pipe.

Is this to frequent? Where should i start looking?

Sump pumps normally have some type of water level monitoring sensor. Very typical is that this is some type of float mechanism that activates one or two switches. The idea behind this sensor system is to turn on the sump pump when the water rises to a certain level. Then the pump should run until the water level falls to some lower level. The better units will have two switches in the sensing mechanism, one which monitors the upper turn on level and another that monitors the lower level. Other cheaper units only have one switch to turn on the pump at the upper level and then use some other scheme to decide when to shut off the pump. That other scheme could be a flapper device, a timed cycle or just hysteresis built into the single sensor switch itself.

If your sump pump is turning on and off in rapid short bursts is probably means one of three things:

The upper and lower level sensor points are adjusted too close together. As soon as the pump goes on it expels enough water to reach the lower level in a rather short period of time.
Another possibility is that the sump pit is too small for the water inflow rate and the pump is able to expel all the water in short order even if the sensor points are adjusted properly.
Then there is the possibility that the sump pump is seriously oversized for the size of the pit and can empty in a short period of time.

From your question details it sounds like the most likely scenario in your situation is the item 1) above.


Ballcock-like mechanism for infinite cycles I'm going to build a mechanism (as simple as possible) like the ballcock system used in flush toilet. But mine should be able to continuously discharge and refill automatically.
I already have a draft idea how to do it: referring to a classical ballcock system I would remove the handle and connect the lift arm to the flush valve flapper.
In this way when the float reach the fill position will automatically trigger the discharge.
Before reinvent the wheel from scratch I wonder if this system has a specific name so I can find other resources or even products.
The goal is to discharge fixed amount of water every a given time. Playing with the geometry I should be able to define the interval of discharge and the amount of water to flush.

What about a "Pythagorean cup" style of device?

from Wikipedia: https://en.wikipedia.org/wiki/Pythagorean_cup
The cup consists of a bowl with a tube in an inverted U-shape. Once the bowl fills beyond the top of the U-tube (step C above) it starts a siphon which drains the volume of the bowl until the siphon breaks. As long as the siphon flow is faster than the inflow, you'll have the behavior you describe - slow, continuous filling, and periodic discharge of a fixed amount of water. The bonus is that there are no moving parts!
As an aside, this is essentially the mechanism that powers the siphon in the bowl (not the tank) of the toilet...


mounting fan/light in very tight enclosed space over shower I am installing a combo shower fan/light over a walk-in shower; it is meant to be installed in the typical fashion (for recessed fixtures) of two adjustable-length brackets meant to span the gap between two ceiling joists.

Unfortunately, as you can see from this image, access is very poor indeed. By way of scale, the opening into the above-shower space is only 7" high.  It will be impossible to improve access.  I had to cut away some sheetrock (on the wall that separates shower from remainder of bathroom) in order to even get here.

I can probably manage to fasten the bracket that runs along the near side of the fan, but for the one on the far side, I think it'll be impossible to fasten the left-hand end, perhaps the right-hand end as well.

So I'm considering alternative mounting options, and seek opinions on these, as well as suggestions of other approaches.

I could simply use a bunch of RTV silicon to glue it to the top of the backing board.  Since the ceiling of the shower is a bit stronger than drywall - 1/2" backing board on 16" joists, plus 1/4"-thick ceramic tile - I'm thinking it can support the unit.   The unit weighs 7-1/2lb.

Maybe I could somehow fasten the far-side bracket higher up on the side of the fan. Then it'd be relatively easy to fasten that bracket to the top of the 2x4 joists, since I also have VERY awkward access from above. I can't do this with the near-side bracket, since the 4" outlet is in the way, but it shouldn't be too hard to attach to the joists as intended.   I hate to screw stuff into the side of the fan box, but I don't see how else, and I can actually access the inside of the unit there and nothing is in the way, so it actually feels pretty safe.

P.S. The unit is rated for "wet" locations, if protected by GFCI (which I will of course do).   And I will vent it properly to the out-of-doors, using the limited access from above.

You're between a sheetrock and a hard place (sorry). I can't count how many times I've seen this done and done it myself. The weight won't be a problem assuming the sheetrock was fastened properly to the joists. I really don't know another way to do it unless you have a six year old that can fit in there.
 What are your plans for venting this to the outside? Do not just vent it into the attic. Good luck.