UL508A grounding conductor

[LMAO]

Is it allowed to use multiple conductors as grounding conductors? According to UL508A Table 75.1 minimum conductors size for 800A service disconnect is 2/0 (copper); can I use 2X2AWG instead?

 

[Dennis Alwon]

I am unaware of any code stating the grounding electrode conductor cannot be paralleled. In a 400 amp service with 2 -200 amp discos we are allowed to run 2-#4's to the electrode(s). I am unaware of what UL 508A is stating.

 

[LMAO]

I am unaware of any code stating the grounding electrode conductor cannot be paralleled. In a 400 amp service with 2 -200 amp discos we are allowed to run 2-#4's to the electrode(s). I am unaware of what UL 508A is stating.

Thanks. I also read UL508A and did not see anything against paralleling grounding conductors.

 

[Jraef]

I would still assume the same rules apply as to CCCs, i.e. not smaller than 1/0.

 

[Dennis Alwon]

I would still assume the same rules apply as to CCCs, i.e. not smaller than 1/0.

That section does not refer to grounding electrode conductor's

 

[Smart $]

That section does not refer to grounding electrode conductor's

There is no section which says you can parallel a GEC using smaller conductors. So you want to parallel 'em. Okay... each has to be the required minimum size.

 

[petersonra]

The grounding electrode conductor is not part of the UL 508a panel. It is field wiring.

 

[infinity]

There is no section which says you can parallel a GEC using smaller conductors. So you want to parallel 'em. Okay... each has to be the required minimum size.

I agree, there is nothing in table 250.66 that states that you can use something other than the size GEC listed in the table.

 

[Dennis Alwon]

I thought the code was permissive---if it does say you can't then you can....you all are changing the rules....LOL

 

[Dennis Alwon]

Tell me this. I can run a smaller conductor for 2- 200 amp panels to each disconnect and be compliant. Can I run those separate grounding electrode conductor's (#4's) to the same meter instead of the disconnect? If I can run it to the disconnect why can't I run it to the meter instead? Seems no different than a parallel grounding electrode conductor.

I have never done it but I can't seem to find where it may be non compliant.


This may be a reason not to parallel.

C) Continuous. Except as provided in 250.30(A)(5) and
(A)(6), 250.30(B)(1), and 250.68(C), grounding electrode
conductor(s) shall be installed in one continuous length
without a splice or joint. If necessary, splices or connections
shall be made as permitted in (1) through (4):
(1) Splicing of the wire-type grounding electrode conductor
shall be permitted only by irreversible compression type
connectors listed as grounding and bonding equipment
or by the exothermic welding process.
(2) Sections of busbars shall be permitted to be connected
together to form a grounding electrode conductor.
(3) Bolted, riveted, or welded connections of structural
metal frames of buildings or structures.
(4) Threaded, welded, brazed, soldered or bolted-flange
connections of metal water piping.

 

[LMAO]

I was looking at wrong table; it is UL508A table 15.1 not 75.1. And it clearly says "minimum wire size" so I am pretty much sure I cannot parallel the ground wires for the same ampacity of minimum wire size.

 

[Smart $]

I thought the code was permissive---if it does say you can't then you can....you all are changing the rules....LOL

Tell me this. I can run a smaller conductor for 2- 200 amp panels to each disconnect and be compliant. Can I run those separate grounding electrode conductor's (#4's) to the same meter instead of the disconnect? If I can run it to the disconnect why can't I run it to the meter instead? Seems no different than a parallel grounding electrode conductor.

I have never done it but I can't seem to find where it may be non compliant..

While staying permissive, you cannot violate the minimum size GEC requirement. Code offers no avenue to determine a parallel smaller equivalent, such as using fractional ampacity for parallel circuit conductors.

Your challenge has merit, but Code (paraphrased) requires the GEC size to be determined according to the largest ungrounded conductor at the point where the GEC is connected. Connecting two GEC's at the meter for two 200A panels would be a violation because each GEC is not sized for the largest ungrounded conductor where it is connected.

 

[Dennis Alwon]

Connecting two GEC's at the meter for two 200A panels would be a violation because each GEC is not sized for the largest ungrounded conductor where it is connected.

And connect it the panel 4" away from the meter and it is compliant. :?

 

[Smart $]

And connect it the panel 4" away from the meter and it is compliant. :?

It is what it is. You should know as well as anyone that requirements do not always exhibit logical conclusions. That said, I know you know the process to get it changed.