running ground wire in complete EMT run


Old 03-17-07, 09:22 AM
ddr is offline
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running ground wire in complete EMT run

Two questions on running a ground wire in a complete EMT run:

1. Iíve always used a ground wire when running coupled EMT in areas that will be closed off completely or be generally hard to get to in case a connection should ever loosen. Recently though, Iíve been running it through conduit as a safety backup regardless of accessibility. Some friends agree with the practice, others say its a waste of wire as long as all connections are tight. (There are no hot tubs or the like involved.) Opinions?

2. If there were a fault and the ground needed, would the current be carried by the ground since the copper is a better conductor, or would it be shared by the wire and the EMT?

Thanks in advance.
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Old 03-17-07, 09:35 AM
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if you have an egc within the conduit, since it must also be bonded to the conduit system, they would both carry a fault current, proportioned by the resistance comparison between the two paths.

to the first question; an EGC within conduit is redundant but from my experiences, a welcome one. I have been to jobs where the conduit did become disjointed for whatever reason (fork lift drivers in mobile home manufacturers are notorious for damage). Once the conduit, if it is the only EGC in use, becomes disjointed, you lose the intended safety of the grounding system. I can;t tell you how many times I have run across locknuts that were not tight as well.

So, is it overkill? in a perfect world, yes. In my world, not at all.
Old 03-17-07, 09:41 AM
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I totally concur.
I always run an EGC inside conduit.
Old 03-17-07, 09:46 AM
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100% in agreement. You can never have too much safety.
Old 03-17-07, 10:11 AM
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I not only agree with racraft, I am going to be nice to everyone and not tell any of the many stories that I have about broken condit and short circuits that caused a hazzard because the "redundent" ground wire was not installed.
Old 03-17-07, 04:50 PM
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Thanks guys; that pretty much settles it for me. Iíll just print out your replies and hand out copies to people who insist Iím wasting wire.

Hey nap -- forklift operators in mobile home manufacturing plants? Iíve got to wonder where electricians see weirder things: commercial jobs because of the potential for destruction or residential jobs because of the potential for screw ups by DIYís like me.

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