NEC - box grounding

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mjc

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What does the NEC say about grounding a box that has wire pulled through it? (no splices, insulated conductors only)
The installtion: A 480v/30a 3phase circuit with an insulated ground wire from a power panel, underground thru 1 inch PVC conduit , thru a metal 'pull box', to another metal box and finally at the load.
Do all metal 'pull boxes' containing non-spliced wire require grounding / bonding ?

Thanks - Mike Detroit,Mi :eek:
 
Re: NEC - box grounding

If you are using non-metallic raceways the equipment ground must be connected to metal boxes. If you are using a metal raceway approved for use as an equipment ground then you are required to connect the equipment grounding conductor to any boxes the circuit conductors are spliced in. See 250.148
 
Re: NEC - box grounding

250.148 seems to only apply to conductors spliced or terminated in the box. Where does it say conductors passing through need to be bonded to the enclosure?
 
Re: NEC - box grounding

Thats what I was finding , 250.148(A)&(B). I'm not seeing anything reguarding the original question.

such as: a box with unspliced wire pulled thru it.

Mike --Det./MI :roll:
 
Re: NEC - box grounding

314.4 requires metal boxes to be grounded. How else would you ground the box if you didn't connect the equipment grounding conductor to it?
 
Re: NEC - box grounding

314.4 says "in accordance with the provisions of Article 250." So again, where in Article 250 does it require conductors passing thorugh an enclosure to be bonded to that enclosure?
 
Re: NEC - box grounding

Bryan, it doesn?t unless the circuit conductors are spliced. If you don?t connect the equipment ground of the circuit to the metal box how else would you ground the box?
 
Re: NEC - box grounding

Bryan,
This is an isolated metallic box in a nonmetallic conduit run, and 250.4(A)(3) requires bonding for this box. If you don't connect the EGC to the box, how do you bond it?
Don
 
Re: NEC - box grounding

-- Don --

Your post seems to clear up my original question. NEC 250.4 (A)3 Bonding of Electrical Equipment .
I personally accept the requirement of 250.4 (A)3 but some would argu that a metallic raceway is permitted as an equipment grounding conductor and 250.148 would only apply to boxes where splices are made not where conductors pass through without splice. What are your feelings about that type of situation ?


Thanks , Mike -- Det. MI :D
 
Re: NEC - box grounding

Mike,
The original post specified PVC conduit. If the conduit is metallic and there are no splices or devices in the box, the EGC would be permitted to pass through the box without a connection to it under the 2002 code. This application is very reason the code was changed. Under the '99 code you always had to bond the EGC to the box, even when the raceway was suitable for use as an EGC. The submitter of the proposal that resulted in the change felt that the requirement to bond the EGC at the box when using a metallic raceway was discouraging installers from making a superior installation by using an EGC with metallic raceways.
Don
 
Re: NEC - box grounding

--Don--

Opps! Sorry for the confusion, when reading my post it does sound like a non metallic installation with metal boxes.

Here it is: The 1 inch pvc conduit comes out of the concrete as 1 inch rigid metal conduit and gets to the load by way of three boxes of a metallic system. An EGC is installed from the Power Panel thru the pvc to the load.

According to your last post I only need to connect the EGC to the box seving the load. These conductors pass thru the other boxes without splice (in a metallic raceway system) and the EGC does not need to connect to them.

I guess that the info about the 2002 NEC change is what I needed to know.
Thanks for the reply. --
Mike Det. ,MI :cool:
 
Re: NEC - box grounding

The metal boxes that the circuit conductors are passing through require grounding if they may become energized. The fact that the circuit conductors pass through the box makes the box potentially hazardous, so equipment grounding is required. As Don has pointed out, if the raceway is nonmetallic, then the box will be bonded by the equipment ground conductor run with the circuit conductors, that is all of the boxes that are connected with that run, not just the box serving the load.

Pierre
 
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