What is the biblical basis to say that prophetic words spoken today are equivalent in authority to scripture? Continuationists, in general believe that all the gifts of the Holy Spirit are still active and available today, including prophecy.

So far as I am aware, prophecy in this context refers to (or in theory includes) foretelling of events, or descriptions of the current state of things independent of any prior knowledge of the one speaking the word (for example the details of someone else's life and some word in relation to that).

More importantly, so far as I am aware, they believe in prophecy, in terms of special revelation received to an individual directly from God (the Holy Spirit), either as a word for another individual, or a prophecy over a nation etc.

My question is, given the assumption of special, direct revelation from God pertaining to modern prophecy (assuming that this is biblical), what is the biblical basis to claim that (at least some of) these prophecies are equivalent in their authority to scripture? I.e are they to be taken as inspired, inerrant, infallible (in-so-far as scripture is also)?
I can't speak for all non-cessationists but the LDS (Church of Jesus Christ of Latter-day Saints) believe:


  in both ancient and modern prophecy (source)


Revelation or prophecy from a prophet, inspired men called to speak for the Lord, is equivalent in authority as the scriptures.

Doctrine and Covenants 1:38


  
  What I the Lord have spoken, I have spoken, and I excuse not myself; and though the heavens and the earth pass away, my word shall not pass away, but shall all be fulfilled, whether by mine own voice or by the voice of my servants, it is the same.
  


Doctrine and Covenants 21:4-5


  
  Wherefore, meaning the church, thou shalt give heed unto all his words and commandments which he shall give unto you as he receiveth them, walking in all holiness before me;
  For his word ye shall receive, as if from mine own mouth, in all patience and faith.
  


See also 


Doc&amp;Cov 1:14-16
Prophets
Amos 3:7