Grounding Conductor Largest Conductor

[Dennis Alwon]

Here is the proposal and comment

Submitter: Dennis Alwon, Alwon Electric Inc.
Recommendation: Revise text to read as follows:
(A) General. Copper, aluminum, or copper-clad aluminum equipment
grounding conductors of the wire type shall not be smaller than shown in Table
250.122, but in no case shall they not be required to be larger than the circuit
conductors supplying the equipment, except when run in parallel according to
250.122(F). Where a cable tray, a raceway, or a cable armor or sheath is used
as the equipment grounding conductor, as provided in 250.118 and 250.134(A),
it shall comply with 250.4(A)(5) or (B)(4).
Substantiation: The use of the term ?in no case? is not quite accurate as there
are times when the equipment grounding conductor (EGC) may be larger than
the circuit conductors. If you have a 1000 amp feeder with 7 runs of 1/0 copper
then the EGC is required to be 2/0 in each conduit.
Panel Meeting Action: Reject
Panel Statement: The phrase ?in no case shall they be required to be
larger than the circuit conductors? applies to the example included in the
substantiation. The panel reaffirms the size of the circuit conductors supplying
the equipment referred to in 250.122(A) is the equivalent area of the circuit
conductors in parallel

 

[TimK]

I guess I will need to cross a couple of wires in the noggin, and accept it as "because they say so". Thanks for your help.

 

[suemarkp]

Mark, can you give an example of where that might be the case?

Roger

I was thinking similarly along Dennis' thinking except for a smaller circuit (e.g. 30A) where you use parallel conductors for voltage drop (a very long lighting circuit) all in the same raceway. I don't agree with the panel's interpretation of their words -- if you need parallel conductors, to me a single large conductor the same cross sectional area as the multiple parallel ones would meet the requirement "not be larger than the circuit conductors supplying the equipment". The CMPs interpretation only makes sense if you also choose to parellel the EGC.

But their rulings are their rulings....