EGC vs EMT (or in EMT)

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ohmti787

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So here's my dumb question: why would you need to run a ground wire from a roof top array all the way down to your inverter if you're using EMT conduit? I keep seeing installations where they're running even bare copper inside EMT conduits, which seems kind of redundant to me. Am I missing something here?

Thanks,
 
ohmti787 said:
So here's my dumb question: why would you need to run a ground wire from a roof top array all the way down to your inverter if you're using EMT conduit? I keep seeing installations where they're running even bare copper inside EMT conduits, which seems kind of redundant to me. Am I missing something here?

Thanks,
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It's a belt and suspenders approach; if stresses to the conduit on the roof and elsewhere outside interrupt or otherwise impede the grounding provided by it, the ground wire backs it up. Plus, a ground wire is cheap, so why not? Also, many AHJs require it.
 
Generally not code required but pretty standard industry practice. And if you had seen as many improperly tightened or just poor quality compression connectors as I have, you'd probably agree it's not a terrible idea.

With some older systems and code interpretations there was a requirement for a GEC from the roof, so the practice may also be partly a hold over from that.
 
jaggedben said:
And if you had seen as many improperly tightened or just poor quality compression connectors as I have
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You would think that since EMT fittings are required to be listed, the listing process would get these junk fittings off the street, but that doesn't really seem to be working. I'm not sure I see improper installation as a valid argument for installing a wire EGC. Seems the solution there is installing/ training people to install properly, and finding a new career if it's just not working out.
 
Whatever. Good people are hard to find these days and I was not going to fire a guy because he forgot to tighten one compression coupling in the fifth EMT run we asked him to do from a ladder that week. I will fire the guy who forgets one in an easy location on every job. As ggunn said, it is an belt and suspenders approach. It is a management decision that provides extra insurance of adequate bonding and protects the company ("we exceeded code requirements"), not an excuse to skimp on installation effort or training. It also accounts for these installs being exposed to elements over time, huge temperature variations, etc. I don't really feel the same way about indoor EMT installations. It's a probability judgment.

As far as the quality of fittings, I agree. But I'm doubtful that the cost to improve fittings to an adequate level to positively ensure good bonding in a long exterior EMT run will not exceed the cost of a 10awg green wire.
 
Little Bill said:
Wouldn't you have to use a bonding bushing on one end if you ran the EGC in the EMT?
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Probably not if the conduit were solidly grounded by means of its connection to a grounded enclosure, but many AHJs require it anyway.
 
electrofelon said:
You would think that since EMT fittings are required to be listed, the listing process would get these junk fittings off the street, but that doesn't really seem to be working.
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Phony stuff coming into country all the time, even breakers that are "not" breakers. As long as there are guys (some not even electricians that are doing electrical work) trying to get the "cheapest" product to meet or beat a competitor or just increase profit it will be an issue. An inspector looking at a job that has hundreds of fittings it would be next to impossible to find a mixture of legit and fake.
electrofelon said:
I'm not sure I see improper installation as a valid argument for installing a wire EGC.
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Now got a question that I never considered before. The compression Wet rated connectors, how efficient are they in maintaining continuity as a EGC path? (Or do they even provide continuity.)
Most of the wireway for a PV system can be on the exterior of a structure, exposed to significant weather impact, extreme cold, heat, driving rain, icing, and wind, all can potentially impact negatively the EGC continuity of the EMT. So wouldn't a secondary path be a "best practice" even if not a code requirement?
electrofelon said:
Seems the solution there is installing/ training people to install properly, and finding a new career if it's just not working out.
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Seems simple enough but competition for qualified persons (or even anyone) is getting worse in the Trades. And then add these companies trying to "get" a market share and offer lower pricing to do that it is a push for speed vs accuracy. Accuracy is usually the looser. Overall "Pride" in workmanship is going away as seen by almost any product you can buy and even in hiring people in the Trades.
 
I will never rely on the conduit to provide an EGC for PV arrays, but the point is moot since most (all?) the AHJs I work with require a wired EGC whether it is code mandated or not. A green wire is cheap and reliable.
 
electrofelon said:
Are there local amendments for the wire EGC for solar or exterior raceways or are these shirt pocket rules?
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I don't know in every case and frankly, I don't care. I don't trust the conduit to maintain connectivity outside in the elements for years, especially in high voltage DC runs. A green wire is cheap peace of mind; DSFDF and YMMV.
 
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