250.30(A)(3) Exception No. 2 & it?s use

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tryinghard said:
We’re installing a new feeder in a concrete building that has an existing CEE (ufer) at the source; and the water pipe is not a qualified electrode as per 250.52(A)(1). This new circuit includes a transformer downstream that would normally have a GEC to the building steel but there is none. We could install another driven type electrode but it will still need to bond to the existing per 250.53(C).

Regarding grounding this new transformer there are three obvious concerns: 1) electrode type, 2) grounding electrode conductor (GEC), & 3) If an additional electrode is installed I understand the bonding can terminate at distribution/panel bus locations if excising electrodes are not accessible. It appears the design below is compliant but it seems weird to use the circuit ground wire as the GEC and not provide another electrode at the transformer.

Is the use of 250.30(A)(3) Exception No. 2 appropriate with this design?
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"the circuit ground wire as the GEC"
The circuit ground wire is an Equipment Grounding Conductor. . 250.30(A)(3) talks about Grounding Electrode Conductor. . Equipment Grounds and Electrodes are 2 different things
 
iwire said:
Did you read the ROP?

You must run a GEC from XO all the way to the buildings grounding electrode system, The EGC is not part of the GES.
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There's your answer. . The Equipment Grounding Conductor is not part of the Grounding Electrode System.
 
This seems to be stretching 250.30(A)(7) ?The grounding electrode shall be as near as practicable to and preferably in the same area as the grounding electrode conductor connection to the system.? This is why I was considering expanding the grounding electrode system by adding another electrode and bonding it to the system ? the best I can anyway.

The 480V 3W feeder has changed to 480/277 4W, I?ve never installed a GEC with a feeder but looking at 250.64 it appears I can, what do you guy?s think (there is no wire fill problem)?

Lastly the CEE is not accessible only its GEC at the source 480V panel bus, does NEC address this?

Anyone can do new construction!!??! :UGH:
 
IMO, If you look at the ROP for the NEC and read what the CMP says about the GEC for an SDS connection at the XO, you see that the EGC can't be used in the GES to your CEE unless you XYZ :rolleyes:

UGH ;)

Comprendo ? :confused:

[Sorry guys, I'm in a recycling mood today. . Got to save the planet, you know ! :) . . Plus I wanted to get XYZ in there somewhere :D ]
 
tryinghard said:
Anyone can do new construction!!??! :UGH:
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LOL, yeah retrofits can be tough.

We run into this problem in many of the old brick and wood mills around here that get converted to office space.

Some of these are 1000' long and 5 floors high, when we add a transformer we have to get a GEC back to the service ........... if no one else has already. If there are other transformers with large enough GECs already we can tap into those via 250.30(A)(4).
 
tryinghard said:
The 480V 3W feeder has changed to 480/277 4W, I?ve never installed a GEC with a feeder but looking at 250.64 it appears I can, what do you guy?s think (there is no wire fill problem)?
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"never installed a GEC with a feeder"
"With" is the key word.
. If your conductor is terminated at both ends at the same enclosure as your feeder, you have yourself an Equipment Ground not an Electrode [ground wire].
. If your grounding conductor goes continuous from its connection on the Electrode System to the transformer XO, transformer ground bar, or first disconnect on the transformer secondary, and doesn't fraterinize with other metal stuff [enclosures] along the way, then it can be an Electrode [ground wire, GEC] that's just sharing a conduit by choice and not be requirement. . Your Grounding Electrode Conductor is usually run solo [either exposed or in pipe] by is not required to be solo. . If it's to your advantage to run it in a pipe with other stuff, go for it.

The Equipment ground is "with" the circuit conductors along the entire length of the run because it is required to be there [215.6,250.134(B),+300.3(B)].
The Electrode ground wire can be with circuit or feeder conductors if you choose to do so.

"(there is no wire fill problem)"
and CCC is not an issue [310.15(B)(5)], so pick your best option, your choice
 
iwire said:
Some of these are 1000' long and 5 floors high, when we add a transformer we have to get a GEC back to the service ........... if no one else has already. If there are other transformers with large enough GECs already we can tap into those via 250.30(A)(4).
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Being lazy as I am, I didn't read the whole thread so ignore this if it's already come up. . Could you hit building steel and use it as your Grounding Electrode Conductor all the way back to the main disconnect ?
 
dnem said:
Being lazy as I am, I didn't read the whole thread so ignore this if it's already come up. . Could you hit building steel and use it as your Grounding Electrode Conductor all the way back to the main disconnect ?
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The buildings have only random sections of steel, the buildings are made of red bricks and wood, they date back to the 1800s.
 
dnem said:
"never installed a GEC with a feeder"
"With" is the key word.
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Explain please?

I do not know of any NEC prohibition against including a GEC with a feeder in addition to the EGC.

It would not be my first choice but I do not see that in itself as a violation.
 
dnem said:
If your grounding conductor goes continuous from its connection on the Electrode System to the transformer XO, transformer ground bar, or first disconnect on the transformer secondary, and doesn't fraterinize with other metal stuff [enclosures] along the way, then it can be an Electrode [ground wire, GEC] that's just sharing a conduit by choice and not be requirement.
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"doesn't fraterinize" was a bad choice of words on my part because, even if you're in steel conduit, I see nothing in the NEC that would require the GEC to be insulated. . So if you go bare wire you're going to get plenty of "fraterinizing" along the entire length. [And if you "fraterinize" while "bare" you might even get a pregnancy, but that's a completely different subject not suitable for our family website].

I should have stuck to the word "terminated". . The GEC can't terminate at enclosures along the way to its destination or it becomes an Equipment Grounding Conductor and you lose your required Grounding Electrode Conductor.
 
iwire said:
dnem said:
"never installed a GEC with a feeder"
"With" is the key word.
Click to expand...

Explain please?

I do not know of any NEC prohibition against including a GEC with a feeder in addition to the EGC.

It would not be my first choice but I do not see that in itself as a violation.
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I was quoting Tryinghard when I said "never installed a GEC with a feeder" and then I talked about the word "with". . It's all about terminations.

If the ground wire terminates at the main disconnect and then not again until the transformer XO, transformer ground bar, or the first disconnect on the transformer secondary, then you have an Electrode ground wire [GEC] and can run it anywhere solo or with "friends" [circuit +/or feeder].

If the ground wire terminates anywhere in between [a subpanel, a junction box, etc], then you have an Equipment ground wire [EGC] and must run it with other conductors. . That would also mean that you are still missing your required Electrode ground wire [GEC].

iwire said:
I do not know of any NEC prohibition against including a GEC with a feeder in addition to the EGC.
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Yes, but my point was that if you terminate it incorrectly, you end up with two EGCs and no GEC.
 
dnem said:
"never installed a GEC with a feeder"
"With" is the key word.
. If your conductor is terminated at both ends at the same enclosure as your feeder, you have yourself an Equipment Ground not an Electrode [ground wire].
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The GEC that I would install would be parallel with the EGC, 250.118, I will be installing a wire type. The GEC and EGC will be THHN and the EGC will be bonding throughout rather than the GEC. I know the GEC is usually in it's own conduit, I still may do this.

I could use conduit system feeding as my EGC but I'm inclined to not.
 
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tryinghard said:
The GEC that I would install would be parallel with the EGC, 250.118, I will be installing a wire type. The GEC and EGC will be THHN and the EGC will be bonding throughout rather than the GEC. I know the GEC is usually in it's own conduit, I still may do this.

I could use conduit system feeding as my EGC but I'm inclined to not.
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If the Equipment EGC is wire or pipe is not an issue.

Be careful using that word "parallel" because if you really are paralleling then you just lost your Electrode ground wire [GEC]. . If you are actually paralleling, you end up with two EGCs and no GEC.

Being in the same pipe doesn't mean that they're "paralleled". . As I said before, It's all about terminations.

If the ground wire terminates anywhere in between [a subpanel, a junction box, etc], then your Electrode [GEC] automatically turns into another Equipment ground wire [EGC]. . That would also mean that you're still missing your required Electrode ground wire [GEC].

The GEC route itself isn't the issue [altho the route should be as short as possible]. . If the GEC is solo or "has company" isn't the issue. . You MUST limit the GEC terminations on one end to the Electrode System connection point and on the other end to the transformer XO, transformer ground bar, or the first disconnect on the transformer secondary. . If you terminate otherwise, you lose your GEC.
 
dnem said:
...You MUST limit the GEC terminations on one end to the Electrode System connection point and on the other end to the transformer XO, transformer ground bar, or the first disconnect on the transformer secondary. . If you terminate otherwise, you lose your GEC.
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So the GEC will terminate at the source bus and not the CEE, how would you interpret this?
 
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