Electrical Question – Grounding EMT in basement applications
Hello,
I’m adding several outlets in my basement and want to have the Romex run in EMT along the walls (basement walls are concrete block). I’m planning on putting the outlets (GFCI protected) in metal boxes. The romex will be run along/through the joists. Therefore, the EMT will not be run all the way back to the electrical panel. Since the EMT will not be run all the way back to the electrical panel, I cannot ground the EMT at the electrical panel. Would it be sufficient and within code (NEC 2014) to only ground the EMT through bonding with the ground wire in the Romex at the metal box were the outlets are installed, or do I need to run a ground wire from the top of the EMT to the electrical box somehow?
Thank you for your advice.
-N
Replies
In that case you are using EMT for physical protection of the romex, not as standard EMT-style circuit. For short lengths I'm thinking code does not require the EMT to be grounded at all, and grounding at one end should be sufficient in other cases. (Unlike an EMT-based wiring system, you're not using the EMT as a ground wire.)
Of course you can dodge the question by using plastic conduit instead.
Don't forget to use appropriate bushings at both ends of the conduit -- you can't have the romex come straight out of the cut-off EMT without a bushing.
Thanks, DanH.
Plastic may be the better/easier way to go in this case.
You MUST Ground EMT
.... And do it several times!
What you are doing is 'changing your wiring method.' Here's how you do that.
You have the Romex end in a box, using the proper connector. In the box you will install a green 'pigtail' that connects to the back of the box. This short wire is needed in every box, and will be connected to your ground wires at every box.
You connect the EMT to the boxes, using the appropriate fittings. The EMT is grounded by its' connections to the boxes..
In the EMT you run proper, separate, green, black, and white wires. It's a fine point, but you're not allowed to run Romex itself in the pipe, or to use the wires from within the Romex.
The boxes are attached to the walls, and the EMT is also fastened to the walls (within 3 ft. of each side of each box, and no more than 1- ft. between supports). Use "industrial" covers for your switches and receptacles, since this is exposed work.
I'm pretty certain you are wrong. There's a difference between using the EMT wiring system (I forget the "official" name) and simply using metal conduit to protect romex from damage (which is often required by code in various situations).
EMT + Boxes = Wiring Method
Which is quite different from using a few inches of concealed pipe to protect a cable.
He's talking about running romex all the way from the breaker panel to the GFCI outlets. He's not converting wiring methods. The EMT is used purely for physical protection, as required by code when in an exposed location of a inhabited area. This is done all the time.
Are you saying there's some code limit on the distance that romex can travel in such situations??
There is nothing wrong with running Romex in EMT if you are not exceeding the fill but you have to compute fill using the widest dimension. That ends up making the cable a pretty big conductor.
I Disagree
The OP said he didn't want to run EMT all the way to the panel. That's not a problem, you can change your wiring method all the time.
He then went on to describe metal boxes, and the pipe being on the face of the wall. That's a change in method, plain and simple. Were he to just have the Romex pop out of the pipe, enter the box, than go back into the pipe .... that's a violation, no matter how you look at it. The solution is to properly change your wiring method.
What if he used plastic boxes? Same issues- plus, plastic Romex boxes are not designed for attaching pipe. The proper way to do this is to as i described - change your method.
Greg's comment about wire fill also sheds some light on the issue. Since Romex typically requires a 5/8" hole, that in turn suggests that the smallest pipe you can use is 1". I suspect that's not what the OP has in mind.
Article 100 is pretty clear .... the wiring method used must provide mechanical protection for the wires, protection suitable to the application. From the OP's description, "sleeves" won't cut it. There are also requirements that the cables be protected from cutting and abrasion - something that can't be provided by the simple end of a piece of pipe.
I am aware of only ONE place in the NEC where such sleeving is called for: when the cable passes through the framing from one floor to another. Note that the context of that requirement makes clear this is for a situation where the sleeve is not accessible later. That's quite a bit different from tacking your pipe to the wall and pushing the cable through it.
I also draw attention to Article 90, which makes plain that you're supposed to learn the trade BEFORE you open the code book. It's not a design manual, instruction manual, or substitute for competence. I also note that every place that licenses electricians requires several years of experience in the trade first .... simply passing the test, attending a seminar, or 'related' knowledge is not enough.
From my old (1981) code book, Article 336 (Nonmetallic-Sheathed Cable), section 6 (Exposed Work):
The cable shall be protected from physical damage where necessary by conduit, pipe, guard strips, or other means.
In the 2014 334.15 (B) says
(B) Protection from Physical Damage. Cable shall be
protected from physical damage where necessary by rigid
metal conduit, intermediate metal conduit, electrical metallic
tubing, Schedule 80 PVC conduit,
250.86 goes on to say
Exception No.2: Short sections of metal enclosures or
raceways used to provide support or protection of cable
assernblies from physical damage shall not be required to
be connected to the equipment grounding conductor.:
"Short" is not defined. They may want bushings on each end of these sleeves.
OTOH if you make up the EMT in metal boxes with the proper connectors and pull your Romex through it you are perfectly legal and a lot safer. It probably works put cheaper too by the time you buy romex connectors and bushings.
Yes, you have to ground EMT, but are you planning on doing this all on your own? If you're not fully confident about this task, maybe consider calling a professional.
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