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Thursday, October 8, 2020
Question:
Hello Code Friends,
I came across a questionable installation that I’d like to ask about. We all know (at least I hope we know) that the general rule for installing a grounding electrode conductor from a separately derived system is that it needs to be a single continuous conductor without a splice. Are there similar rules about raceways if they’re used to run this electrode conductor? I know that 250.30(A)7 directs you to 250.64(E). There are a few things there, but what I saw was a transformer's connection to building steel was a #6 (sizing was correct). Still, they had it leave the transformer in 3/4” EMT to a gutter, pulled through the gutter into a 480V panel (EM system, this transformer was connected to normal power, so not the same system), it was pulled through the panel (used as a raceway) in a different EMT conduit to a second gutter, pulled through yet a second 480V panel (this one was normal power) and finally, there was about 7’ of PVC finally bringing that #6 to building steel. I think it’s fair to say that clearly, this isn’t ‘best practice’ but I can’t find a code article which prohibits you from doing it. Typically, at least when I’ve done it in the past, I have a single unbroken run of conduit for the continuous grounding electrode conductor, but do you guys know of anything that provides more clarity on this? It just kinda erked me because it reeked of laziness!
Thanks,
Brennan Salibrici
A
Answer:
Hello Brennan,
If a ferrous metal raceway is installed to contain a grounding electrode conductor, then the ferrous metal raceway must be bonded as required by Section 250.64(E). This allies to continuous raceways and separate sections of ferrous metal raceways that contain a grounding electrode conductor.