When we purchased our present house there was already a run of 3' diameter gray PVC conduit run in a chase from the unfinished basement to the attic above the second story. There are about 6 runs of
12-2/gnd Romex run from through this (as well as a few telephone, cable TV and home network cables).I am bothered by several things about this arrangement, and would like to clean it up if practical. In part this is driven by a requirement to run several new circuits to the attic to feed some new remodel work. Also, quality / code wise the present Romex exits at the top of the PVC conduit, is folded over the edge, and is banded to the conduit with electrical tape. This bothers me, as I'd rather not use this approach for new runs.
My concept involves:
- Cutting the existing Romex where it exits the conduit in the attic and pulling it back down to the basement.
- Adding two large junction boxes, perhaps 12" x 12" x 8", one connected to both the basement and attic ends of the 3" conduit.
- Replacing the vertical runs with #12 THHN. This would use less volume, and simplify adding additional circuits.
My questions are. Is this OK? Better that existing / Worse? Other suggested approaches?
A big part of what bothers me about the existing arrangement is the "hanging weight" of the Romex vertically unsupported through 2+ stories. Just doesn't seem wise. So several separate questions:
- What is the allowed unsupported vertical run length for #12 THHN?.
- Would I be aby better off, to keep the wires from 'swinging' (can't think of a better word) inside of the 3" conduit, to run several 1" EMT lengths up inside of the 3" and put the THHN inside of thise?
Thanks for your thoughts. Bruce