EGC in parallel runs

[sbutler]

Per 250.122(F), it requires the GEC to be sized per table 250.122 for each parallel run regardless of the feeder size. The contractor installed parallel (2 -runs) #350's with a #4 GEC connected to a 600A disconnect switch. By table 250.122 and 250.122(F), it looks like #1 is required in each run. Does anyone know if there is an exception that allows for a smaller GEC?

Thanks for any and all replies.

 

[roger]

You are refering to the EGC not the GEC and if the OCPD is 600 A you are correct, a #1 would required.

Roger

 

[qcroanoke]

So, paralleled grounds are not required to be at least 1/0 per 250.122 (F). Interesting.... I did not know that. I can go home now, I learned something today!

 

[sbutler]

Correct....EGC. Does anyone see a problem with pulling in and additional EGC to equal or exceed the #1 if it was installed versus pulling out the #4's and re-installing #1's?

 

[pete m.]

Correct....EGC. Does anyone see a problem with pulling in and additional EGC to equal or exceed the #1 if it was installed versus pulling out the #4's and re-installing #1's?

The only problem I see is that it would not be code compliant. What is the raceway being used? If it is one of the types in 250.118 the EGC could be omitted all-together.

Pete

 

[sbutler]

RGSC. So by code, we are covering 1 and 2 of 250.118 and all is well.

What is violated by adding another conductor?

 

[Twoskinsoneman]

RGSC. So by code, we are covering 1 and 2 of 250.118 and all is well.

What is violated by adding another conductor?

250.122(F) says each conductor shall be sized based on the OCPD IAW table 250.122...

Doesn't leave room for saying "I've got two #4s in there so that's just as good as a #1"

 

[sbutler]

Point well taken. To stay compliant, I will make them either install the #1 or leave the #4 and ensure the RGSC is bonded properly to comply with a combination of ways as allowed by 250.118 (1) and (2).

 

[pete m.]

Point well taken. To stay compliant, I will make them either install the #1 or leave the #4 and ensure the RGSC is bonded properly to comply with a combination of ways as allowed by 250.118 (1) and (2).

FWIW, the conductor (4awg) left in the raceway would not be considered an EGC due to the fact it is not correctly sized.

IMHO, installing the correct size conductor would be the way to go.

Pete

 

[qcroanoke]

Point well taken. To stay compliant, I will make them either install the #1 or leave the #4 and ensure the RGSC is bonded properly to comply with a combination of ways as allowed by 250.118 (1) and (2).

Check your job specs. An EGC may be required by the specs. and the #4 is not code compliant. If it isn't required make them pull it out and if it is required make them pull in the correct size wire.

 

[sbutler]

I re-thought my position based on the fine commentary. I am requiring them to remove the #4 and install the #1 per 250.122. Neat, clean and code compliant.

Thanks for your help guys.

 

[pete m.]

This does bring up an interesting thought...

How many would see it as a code violation to connect the 4awg conductor as an EGC even if the raceway qualified as an EGC?

Pete

 

[sbutler]

I would not as 250.118 says it can be any combination of the items listed. (1) says it can be a conductor...doesnt say what size even though we all agree it should be sized per 250.122. (2) says it can be RGSC. The situation I have now (#4 and RGSC) seems to fit. however, as i mentioned, i am having it removed and a #1 installed....which brings us back to your original question........as the RGSC is still going to be there.

 

[Strife]

The EGC in each parallel conduit has to be of sufficient size to trip the OCPD which is in the table for equipment grounding conductor (this is NOT the Grounding Electrode Conductor.
IMO if the conduit is GRC then the grounding is covered, but, if a redundant EGC is installed, then it has to comply with NEC.
I had a similar (somewhat) situation with a kitchen peninsula the engineer put a small appliance receptacle in the back wall of the peninsula. Problem was the counter top was longer than 12" so even if we put it highest possible was still more than 12". Inspector failed it. We eliminated that receptacle completely as we already had another receptacle satisfying the peninsula rule.

So, paralleled grounds are not required to be at least 1/0 per 250.122 (F). Interesting.... I did not know that. I can go home now, I learned something today!

 

[Twoskinsoneman]

This does bring up an interesting thought...

How many would see it as a code violation to connect the 4awg conductor as an EGC even if the raceway qualified as an EGC?

Pete

This is interesting. I guess it would be a violation because as soon as you connect it is an undersized EGC. But I guess you could just disconnect it, tape it off and leave it...

Making the system safer...(less impedance for fault)... violation...

 

[tkb]

So, paralleled grounds are not required to be at least 1/0 per 250.122 (F). Interesting.... I did not know that. I can go home now, I learned something today!

So what code section allows the EGC to be under 1/0 when paralleled?
I have a feeling this has been discussed before.

 

[chris kennedy]

So what code section allows the EGC to be under 1/0 when paralleled?

310.4.

310.4 Conductors in Parallel.
(A) General. Aluminum, copper-clad aluminum, or copper conductors of size 1/0 AWG and larger, comprising each phase, polarity, neutral, or grounded circuit conductor shall be permitted to be connected in parallel (electrically joined at both ends).

Note that (A) makes no mention of EGC's.

(B) Conductor Characteristics. The paralleled conductors in each phase, polarity, neutral, grounded circuit conductor, or equipment grounding conductor shall comply with all of the following:
(1) Be the same length
(2) Have the same conductor material
(3) Be the same size in circular mil area
(4) Have the same insulation type
(5) Be terminated in the same manner

Now note that (B) mentions EGC's. Therefore the EGC's are not subject to the 1/0 requirement in (A).

 

[Rockyd]

I re-thought my position based on the fine commentary. I am requiring them to remove the #4 and install the #1 per 250.122. Neat, clean and code compliant.

Thanks for your help guys.

Now we are talking about an engineer with class! Cool that the forum will help keep another installation code compliant.

 

[tkb]

310.4.

Note that (A) makes no mention of EGC's.

Now note that (B) mentions EGC's. Therefore the EGC's are not subject to the 1/0 requirement in (A).

Works for me. :grin: