NM (Romex) cable in EMT/PVC conduit? (specific situation)

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Old 09-04-18, 03:01 AM
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Question NM (Romex) cable in EMT/PVC conduit? (specific situation)

I know parts of this topic have been covered in other threads but I am not 100% sure it covered my exact scenario. The closest I found was the following:

Question about using EMT/conduit for exposed work
https://www.doityourself.com/forum/e...osed-work.html

So I have an unfinished basement with open ceilings. The previous owner has a few wall outlets that seem to be using BX cable from the panel through the ceiling joists to the general area. Then the BX cable goes into EMT conduit from just above the ceiling joists down to the outlet.

I would like to install some new circuits from the panel to new locations, as well as possibly replace the existing runs. Considering replacing the existing 14/2 with 12/2 so I can add a 20A breaker since this will be a workshop with a bunch of power tools.

Originally I envisioned taking the same approach and running NM cable from the panel into the existing EMT for the existing runs and PVC for the new runs. I started to do more research to make sure my approach was safe and meet code requirements. So it seems that running the NM cable through holes in the ceiling joists is acceptable, but running NM cable in any kind of conduit is not. I know there is a debate on that last point but I would like to take the safer approach and just avoid it. So when going through conduit (EMT/PVC) it is recommend to use THHN which is just the since wire where I would need to run a minimum of the three for hot, neutral, and ground. I think this is not too bad if the full end to end run is entirely conduit, but I would think that running the 3 individual wires for each circuit through the series of ceiling joists is gonna be a huge pain and not easy.

Thinking about it further, I guess I can put a junction box in the ceiling near the the location where the conduit running from the outlet to the ceiling is located. This would allow me to run NM from panel to junction box and then run THHN from junction box, through conduit into outlet box. Not a huge fan of this as IF I ever wanted to cover up the ceiling with sheet rock, there would be a lot of junction boxes that I would need to keep exposed (there are already some existing ones). I also wondered if running the NM cable from the panel up to the start of the conduit and then using a cable ripper to remove the sheathing from the NM cable. This would leave just the individual wires (similar to THHN cable) to run through the conduit to the outlet box. Should I just follow the same approach and run BX cable from the panel straight into the conduit and into the outlet box?

So I am not 100% sure which is the best approach based on safety, best practices, and code (NY-Westchester). Any advice or additional information would be greatly appreciated.


A few other quick questions:

1)I am also planning on adding a lot more ceiling lights (workshop lights). I planned on installing more electrical boxes in the ceiling between the joists. Instead of hard wiring the light fixtures in them I would like to install an electrical outlet in the box. Several of the workshop lights I have are the plug in type and I would like to keep them that way (not modify them). I think I could run NM cable (14/2) from the panel, through the ceiling joists directly to the ceiling box. Is installing an electrical outlet in this manner in violation of any codes?

2)I believe it is code to have a service outlet right near the panel. I have one in place with a GFCI outlet installed. Am I allowed to tap off of that box and extend add another, lets say above it or on the other side of the panel? It would only be maybe 12-18" away and I would use EMT and THHN cables for that short run.

Thanks in advance..!
 
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Old 09-04-18, 05:32 AM
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Hi, Art. 334 , NM cable shall be protected, I think you maybe over thinking this.
“(C) In Unfinished Basements and Crawl Spaces. Where cable is run at angles with joists in unfinished basements and crawl spaces, it shall be permissible to secure cables not smaller than two 6 AWG or three 8 AWG conductors directly to the lower edges of the joists. Smaller cables shall be run either through bored holes in joists or on running boards. Nonmetallic-sheathed cable installed on the wall of an unfinished basement shall be permitted to be installed in a listed conduit or tubing or shall be protected in accordance with 300.4. Conduit or tubing shall be provided with a suitable insulating bushing or adapter at the point the cable enters the raceway. The sheath of the nonmetallic-sheathed cable shall extend through the conduit or tubing and into the outlet or device box not less than 6 mm (¼ in.). The cable shall be secured within 300 mm (12 in.) of the point where the cable enters the conduit or tubing. Metal conduit, tubing, and metal outlet boxes shall be connected to an equipment grounding conductor complying with the provisions of 250.86 and 250.148.”

Excerpt From
NFPA 70®, National Electrical Code® (NEC®), 2014 Edition
National Fire Protection Association (NFPA)
https://itunes.apple.com/us/book/nfp...12925892?mt=11
This material may be protected by copyright.
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Old 09-04-18, 08:26 AM
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There is no problem with pulling NM cables through short sections of conduit for protection when one end of the conduit is left open. There is also no problem pulling a single NM cable through any distance of conduit. The only concern is that you need to have a bushing on the open end of the conduit so the cable doesn't get cut on the sharp end. Arlington Industries makes a drive-on plastic bushing specifically for this purpose. It's common practice to run NM cable in the basement ceiling and run a piece of conduit down the concrete wall to an outlet box.

The forbidden part is that you can't (practically) install multiple NM cables in a conduit because code requires calculation of the conduit fill ratio based on the widest diameter of the cable. Essentially multiple 12/2 NM cables would figure out to require a conduit diameter about the same as a 400A service.
 
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