Ground Pig Tails

[winnie]

We all agree on the letter of the code: If the circuit conductors are increased in size, then the egc must also be increased in size. If you have 15 or 20A circuits yet ran #10 all the way to the fixtures, then the letter of the code requires you to use #10 for the egc.

If you ran #10 to each junction box but #12 from each circuit conductor splice to the fixtures, then the letter of the code would allow the same for the egc.

If you ran #10 for the circuit conductors all the way to the fixtures but used the conduit as the egc, then imho the letter of the code would require #10 for your egc pigtails.

As others have noted this will not make any significant difference in the performance of the circuit protection. The purpose of this code requirement is to ensure a low impedance egc and a short length of #12 won't make a big difference there.

I think your best bet is to admit to the inspector that you got this wrong and then request a variance on the basis of the impedance of a long length of emt plus 1 foot of #12 vs the impedance of the long length of #10. Recently there was some discussion of the impedance of emt.

Jon

 

[LarryFine]

I would also print out this thread for her/him to read. It'll explain better than anyone could verbally.

 

[Hawkeye Gabe]

I would also print out this thread for her/him to read. It'll explain better than anyone could verbally.

Thank you All for your input.i had a good feeling I ran across that section and was just hoping I was reading it wrong. These are all great points also a good idea to print this out. I am actually helping a guy out after he did some dirty electrical install. Normal-Emergency and Legally required systems all intertwined. I see why he’s beating us up. He’s doing his job where we did not. He’s a really good inspector caught a bad install so he’ll want to see it all. I don’t blame him.

THANK YOU ALL- Great forum - this was my first post

 

[Hawkeye Gabe]

Are the fixtures mounted to the junction boxes? Hate to say it but ouch this one is going to hurt.

yes fixtures are mounted to j-box in concrete. All conduit is SCH 40 Pvc

 

[flashlight]

yes fixtures are mounted to j-box in concrete. All conduit is SCH 40 Pvc

Therefore, there is a #10 EGC in the conduit and you are not relying on EMT. Good luck with inspector.

 

[winnie]

yes fixtures are mounted to j-box in concrete. All conduit is SCH 40 Pvc

Just to clarify the exact setup:

#10 circuit conductors either directly connected to the fixtures or connected with #10 pigtails
#10 egc in conduit connected to the fixtures with #12 pigtails

?

Jon

 

[infinity]

Just to clarify the exact setup:

#10 circuit conductors either directly connected to the fixtures or connected with #10 pigtails
#10 egc in conduit connected to the fixtures with #12 pigtails

I was under the impression that the pigtail is connecting the EGC to a metal deck box. If it's connecting only to the fixture then I don't see why it needs to be any larger than the fixture wires on the fixture.

 

[zbang]

I was under the impression that the pigtail is connecting the EGC to a metal deck box. If it's connecting only to the fixture then I don't see why it needs to be any larger than the fixture wires on the fixture.

Same here.

 

[Knuckle Dragger]

Suppose the conduit was the only EGC and the circuit conductors were #10. What size would the pigtails need to be?

xactly!

 

[synchro]

If you're still on the 2017 NEC, 250.122(B) says:

"Where ungrounded conductors are increased in size from the minimum size that has sufficient ampacity for the intended installation, wire-type equipment grounding conductors, where installed, shall be increased in size proportionately according to the circular mil area of the ungrounded conductors."

To me this use of the word "where" means that the EGC must be increased where it is run with ungrounded conductors that have been increased in size, such as between the boxes in the OP's situation. But at the location where pigtails or fixture wires are connected to this run, and their ungrounded conductor(s) are not increased in size, then this is not where the mandate to increase the size of an EGC should apply.
This is along the lines of what Infinity and Winnie have posted.

In the 2020 NEC the word "where" has been replaced with "if". So there no longer appears to be any limitation on where the EGC needs to be increased in size, even if there's only a short length of ungrounded conductor with an increased size. Hopefully, reason will prevail when this is applied.
The 2020 does have an exception that EGCs shall be permitted to be sized by a qualified person.

 

[Hawkeye Gabe]

Just to clarify the exact setup:

#10 circuit conductors either directly connected to the fixtures or connected with #10 pigtails
#10 egc in conduit connected to the fixtures with #12 pigtails

?

Jon

We have #10s wire running in pvc conduit in the concrete deck to 4sq metallic j-boxes. #12 pig tail to the j box. Then connected to #18 manufactures
fixture wires.
#10 circuit conductors and #10 egc in the PVC conduit. - hope this is clearer.;

Thanks ALL.

 

[infinity]

So the issue that the inspector has is the #12 pigtail to the box

 

[Hawkeye Gabe]

So the issue that the inspector has is the #12 pigtail to the box

Correct, saying the egc to the j box needs to be the same size as the egc in the raceway.

 

[winnie]

We have #10s wire running in pvc conduit in the concrete deck to 4sq metallic j-boxes. #12 pig tail to the j box. Then connected to #18 manufactures
fixture wires.
#10 circuit conductors and #10 egc in the PVC conduit. - hope this is clearer.;

Correct, saying the egc to the j box needs to be the same size as the egc in the raceway.

IMHO the inspector is wrong.

The EGC must be increased in size to match the increase in size of the circuit conductors.

So if you have a 20A circuit (which normally would be on #12 circuit conductors with #12 EGC) run on #10 circuit conductors, then you must also use #10 EGC.

But say for example that you run the circuit conductors in multiple sizes, say 100 feet of #8 followed by 100 feet of #10, then 100 feet of #12. The EGC would similarly be required to be 100 feet of #8, then 100 of #10, then 100 of #12. The EGC does not have to be a constant size throughout.

If you ran your circuit conductors as a 'backbone' of #10 with #12 pigtails, then your EGC would similarly be required to be #10 with #12 pigtails.

Now, if you ran your circuit as #10 and then spliced the manufacturers #18 wires directly to the #10, then the inspector would have a point, though one that is IMHO unreasonable. The #18 manufacturers wires are part of the fixture, not field wiring. So the argument is that you ran #10 all the way to the fixture, and thus you would have to run a #10 EGC all the way to the fixture. If this is the case, then I would say that the inspector is plausibly correct per the letter of the code, but would ask for a variance, since the #12 is clearly larger than the fixture wires.

 

[wwhitney]

I'm going to say that as the grounding pigtail is not run with the ungrounded conductors, then 250.122(B) does not apply to it. It only applies to the EGC in the conduit run with the ungrounded conductors. That is a reasonable interpretation of the word "where" at the beginning of 250.122(B).

Cheers, Wayne