Can 3d printers be operated at voltages above 24 volts? Going from 12V electronics to 24V produces a reduction in the overall amount of heat generated in the electronics (that are not intended to get hot). These include the motors, drivers, mosfets and pcb traces.

Why then given that 48V power supplies and electronic components cost exactly the same as their 24v counterparts, are there no 48V 3d printers?

Is there a saftey aspect to 48V that needs to be considered? 

EDIT: Yes 48V fans cost a little more but it's not exorbitant. It seems odd to move from 12 to 24 to get half as much heat, when you could move from 12 to 48v and get a quarter as much heat.
I believe the main issue is the voltage regulators and capacitors on your standard print main board are not rated for 48V. You can find some CNC shields that can handle up to 36V but these are lacking 3d printer features such as heater ports and only have 4 stepper slots.