New Shop Wiring

[bob pieroway]

Hi All
First time on this forum and it looks real nice.I'm going to be moving my shop to an unfinished basement and have to install a sub-panel and all the wiring for lights and equipment. My thought right now is to use all 12-2 romex for the lights and electrical outlets.Of cause I'll run a few circuits for the lights and power for the tools and some heavier 220v lines.Would it be ok to run 12/2 romex to the metal junction boxes and then 1/2" conduit down the wall to the outlets or can I just install a few 2"X 3/4" boards down the wall and run the romex down the board? From what I've read it's not code to run romex cable thru the conduit, because it's not type excepted. So I can run type THHN from the ceiling junction boxes thru the conduit. Sure would be easier just working with the romex.The new shop will be a 1000sq ft in the basement in comparison to my 1 car garage shop which is around 230sq FT so I'm really excited about getting more space.My new house is in Hawley Pa. if any of you are in that area.
bob

[Dan Friedrichs]

Hi Bob - welcome to SMC.

You can use Romex in conduit, but it makes some minor changes to the number of wires you can run in the conduit. If you don't plan on running multiple runs of Romex in a single 1/2" conduit, you have nothing to worry about.

[Rob Russell]

Bob,

It's basically going to come down to what your building inspector thinks "subject to damage" is. If NM-cable stapled to a board is unprotected enough in your shop so boards could lean against it, then you might have a problem. It's fine to use conduit to sleeve the NM-cable as it comes down the wall for protection. You do need to use a conduit that's large enough based on the conduit fill tables. For something like Romex, you'd need to measure the widest part of the cable, treat that as the diameter of the cable and (assuming 1 run of Romex in the conduit), use conduit that's allows for no more than 53% of the interior cross-section to be filled.

If you're using EMT and 1 run of Romex, 1/2" EMT allows a max calculated cable cross section of 0.161". 3/4" EMT allows 0.283".

Measure a piece of the 12/2 Romex you plan to use, figure out what the largest dimension is, divide that number in half, square it and multiply by 3.14. If that's larger than .161, you need to use 3/4" EMT.