Conduit as EGC

[infinity]

Let's not forget that, if the EGC needs to be upsized for VD, so will all of the conductors, and thus so will the conduit itself.

Larry, what do you mean? Are you saying that a larger conduit may be necessary since you're up sizing the conductors?

 

[SEO]

If larger conductors are installed for voltage drop the conduit would have to be sized to handle the larger conductors anyway.

 

[hurk27]

Let's not forget that, if the EGC needs to be up-sized for VD, so will all of the conductors, and thus so will the conduit itself.

I would have to say the conduit was already "pre-up-sized" since it can handle any fault larger then any circuit that could fit in it? and would have less voltage drop of the largest size circuit conductors that would fit in it, before the fill requirements would cause you to up-size the conduit anyway?:-?

 

[Pierre C Belarge]

Let's not forget that, if the EGC needs to be upsized for VD, so will all of the conductors, and thus so will the conduit itself.

I am not sure that the NEC requires the EGC to be upsized for voltage drop.



With that said, if the ungrounded conductors are upsized for any reason, the Equipment ground conductor is also required to be upsized 250.122(B).


The title of table 250.122 starts with the word; MINMUM
There is a note at the end of the table.
"Where necessary to comply with 250.4(A)(5) or (B)(4), the equipment grounding conductor shall be sized larger than given in this table."


Meaning that the MINIMUM size as per Table 250.122 may not be large enough to be an "Effective Ground Fault Current Path".


This could be for reasons such as splices, length, etc...

 

[fbhwt]

Conduit as EGC

That could be something specific to a job but is not an NEC requirement.
Ask the oracle that shared this wisdom with you to show you the code section. Unless its your boss, the owner or your foreman of course, then just do what you are told. They may have sold your job that way.:grin:

Great wording,and the first two you are correct, this has to do with some old work I was looking at the other day where someone had a 200a fused disconnect feeding a panel,no egc, the neutral bar was bonded to the can, the neutral was also bonded at the disconnect
to a ground bar in a trough with a 2/0 going to a cold water line. I had said that the conduit was fine as a egc, he said that anything over 60a required a seperate egc. Not going to get into all the other problems with the above which I'm sure everyone will comment about and I look forward to reading your comments. This is an existing situation where I was asked to look and see what needed to be addressed. It all started when the "Oracle" put his hand on the disconnect and it was warm, upon opening the disconnect he noticed the THW wire had a shiny wet look to it. Thanks for all the replies.

 

[don_resqcapt19]

Thank you Don
I agree that the increase in size for long runs should compensate and provide a suffeicently low impedance path for faults in the range up to 500%of the cont rating of the ocpd

but on the other hand (A) (5) mentions the maximum ground fault and I think in such cases it may require even under extreme fault condictions I would thing the intent is to maintain the intergrety of the egc path??

What's your thoughts.

Charlie,
Yes, you or the engineer should look at the available fault current and in some high current installations, you do have to upsize the EGC so it doesn't burn open before the OCPD operates.