EMT used as the EGC?

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sdrusace

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Hello forum members, this is my first post on this forum. I've been reading it for a couple of years now, and I think it is fantastic. My question is concerning the use of 3/4 " EMT as the Equipment Grounding Conductor on a lighting branch circuit. I have a contractor on one of my jobs who argues that because of Article 250.118 (4), and 250.134 (A), he can use the conduit as his EGC, and doesn't have to pigtail his junction boxes (in which the CCCs have joints made up) to the ground wire within the conduit. I say that he does have to pigtail the grounds in the boxes because of 314.4. Also, the handbook states, in 250.134, " To keep the impedance at a minimum, it is necessary to run the equipment grounding conductor IN the same raceway or cable as the circuit conductor(s)." I also know that if a junction box is not pigtailed, if the conduit comes apart between the box and the panel, the box is no longer grounded, and could become energized if a short occurs.
Is there something in Article 250 that I am overlooking? Any answers would be greatly appreciated. :)
 
EMT is permitted to serve as an EGC, per 250.118(4). Connection of an outlet box to the EMT (i.e., using the nut and the threaded connector) causes that particular "non-current-carrying metal part" to be connected to an EGC, as required by 250.134. So I agree with your contractor. Perhaps adding a pigtail might make the setup marginally better, but the code does not require it.

Welcome to the forum.
 
Wow, only 45 minutes since my post and already 6 answers (well, sort-of) - this forum is truly awesome! I have seen 1/2" and 3/4" conduit come apart many, many times over drop ceilings. And sometimes, the end of the conduit would dig into the insulation of the hot wire, and pow!! In this situation, if the closest box isn't pigtailed, and some poor electrician (or another tradesman) is holding that conduit, and he's on a ladder with half of him up into the ceiling - you have the potential for a serious injury to occur, from shock and a fall. Unfortunately, in this case the specs for the job are vague, they only state that the NEC must be adhered to. I can recommend, but I cannot demand. Thanks fellas for your input!
 
I believe that 250.148 applies. If there is an EGC wire run in the conduit, then it must be pigtailed to every box in every box where the circuit conductors are spliced.

I absolutely agree that it is legal the EMT as the EGC; in fact since the EMT is an EGC it is one of the 'separate equipment grounding conductors associated with the circuit conductors' that must be joined within the box.

Now, since the EMT is legal as an EGC, if the separate EGC wire were removed then the pigtail would no longer be required.

-Jon
 
jumper said:
If a EGC wire is present and spliced in a metal box doesn't 250.148(C) say you have to ground the box to the wire EGC.
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Looks like you're right. 250.148(C) says that a connection shall be made between the one or more grounding conductors and a metal box by means of a grounding screw that shall be used for no other purpose.

So, if I'm reading this correctly, if you have EMT going into a metal box AND a copper grounding conductor, then yes you have to provide a pigtail to the box.

If the EMT is being used as the EGC, the fitting that attaches the conduit to the box will satisfy 250.148(C), and no pigtail is necessary.
 
sdrusace said:
Unfortunately, in this case the specs for the job are vague, they only state that the NEC must be adhered to.
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Can you clarify one aspect of the situation for us? Will a separate wire be run inside the conduit, that wire being an EGC? Or is the conduit intended to be the one and only EGC?
 
DetroitEE said:
Looks like you're right. 250.148(C) says that a connection shall be made between the one or more grounding conductors and a metal box by means of a grounding screw that shall be used for no other purpose.

So, if I'm reading this correctly, if you have EMT going into a metal box AND a copper grounding conductor, then yes you have to provide a pigtail to the box.

If the EMT is being used as the EGC, the fitting that attaches the conduit to the box will satisfy 250.148(C), and no pigtail is necessary.
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Correct - [I can't find my own post] - this was discussed a couple of weeks ago and that was the concensus [EMT alone = no pigtails; EGC conductor within the conduit - then pigtail].
 
Corey Zachel said:
I've heard the same claim about pvc40 in a trench. bottom line, it happens.
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Do you realize that in article 517.13, the metallic raceway is the primary EGC and the insullated conductor is the secondary.

BTW, I don't think schedule 40 pvc is recognized as an egc in 250.118. ;):grin:

Roger
 
roger said:
Do you realize that in article 517.13, the metallic raceway is the primary EGC and the insullated conductor is the secondary.

BTW, I don't think schedule 40 pvc is recognized as an egc in 250.118. ;):grin:

Roger
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yes and i was referring to the claim of properly installed not egc, but you knew that.
 
charlie b said:
Can you clarify one aspect of the situation for us? Will a separate wire be run inside the conduit, that wire being an EGC? Or is the conduit intended to be the one and only EGC?
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Yes, the contractor has pulled a #12 ground wire in the conduit, his only reason for that is to hook it to the ground terminal on switches and receptacles. Now that I've read 250.148(C), thanks to "jumper", I can't see where the contractor has a choice, the boxes have to be pigtailed. I can't remember any occasion previously where I did not pigtail ANY junction box, and it sure does make things alot safer. By the way, when I referred to seeing conduit come apart like that, it was previously done by OTHER electricians, I used to always double-check all of my fittings for tightness. Thanks again guys! :)
 
Agreed, pigtail required when running EGC.
As far as the whole "the conduit will be fine if installed properly" argument has come up several times on the forum. Personally I think it's the engineers responsibility to deliver a properly considered design. As much as I agree that a properly installed metal raceway is fine both by code and practice, I don't choose the contractor on the job and have to assume that the installation of any project has an equal chance of showing up on this forum with the title being something like "Pic of the day" ;) So I specify the ground wire anyway.
 
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