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 Post subject: A question about grounding
PostPosted: Fri Apr 03, 2009 8:08 am GMT ErdGMT 
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Catfish
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Joined: Fri Sep 29, 2006 10:57 pm GMT EthGMT
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I am wondering what the consensus is on using conduit as the ground instead of running a ground wire through the conduit. From what I've read, the conduit really is better than a wire, at least up to a few hundred feet, BUT, if the conduit isn't put together properly then there is a major problem.

So will the local inspectors here in Florida allow the conduit to be used as the ground? It seems that the NEC allows it, but then I've read that in some places the local people require a grounding wire.

Also, if a grounding wire is needed, which is correct: that it needs a ground equal to the largest wire in the conduit, even if that wire is oversized, or that it needs at most a 6awg wire?


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 Post subject: Re: A question about grounding
PostPosted: Fri Apr 03, 2009 12:25 pm GMT ErdGMT 
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Guppy
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Joined: Mon Mar 20, 2006 7:58 pm GMT EthGMT
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Location: pittsburgh
conduit may present discontinuity and high resistance points and is really only meant to physically guide and protect the wiring.


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 Post subject: Re: A question about grounding
PostPosted: Fri Apr 03, 2009 1:23 pm GMT ErdGMT 
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Catfish
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Yes, it can be bad if the conduit isn't connected properly. It can get incredibly technical. From what I've read, some connect the grounding nut by tightening the conduit and holding the nut, but it seems that it is required to hand tighten the nut and then tighten it at least 1/4 turn more, to scratch the paint off the surface of any metal box. There should be some way though to test if the conduit is acting effectively as the ground, but the test instrument probably costs $1000.

I started wondering because I read: http://www.steelconduit.org/pdf/TechTal ... unding.pdf


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 Post subject: Re: A question about grounding
PostPosted: Fri Apr 03, 2009 8:36 pm GMT ErdGMT 
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Red Cobra Delta Guppy
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I have never heard of, or done personally or see in the wild inspected electrical that used conduit for ground. It can easily be pulled part without any indcation that this has happened. For your Bartow job, pull a green wire the same size as the PV runs and you will have no issues with Polk County inspectors on that aspect of the installation


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 Post subject: Re: A question about grounding
PostPosted: Sun Apr 05, 2009 3:44 pm GMT EthGMT 
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Catfish
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Joined: Fri Sep 29, 2006 10:57 pm GMT EthGMT
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Yes, I figured that no matter having a grounding wire must add to the safety. It seems too that the ground wire should be insulated instead of bare if it is in conduit.

I did end up wishing I would have listened closer to Larry at G&G Electric when he said to step up a size or two for conduit, but having 1 1/2" conduit running in the garage seemed so much more industrial, so I stayed with the 1" conduit.

I was just wondering too if you had the name of the electrician who oversaw your installation there in Lakeland. I was real happy with your suggestion of Robert Haug for the P.E. There are a few last details that I wanted to make sure were OK and Larry is pretty busy at the moment.


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