Considering the note on NEC table 250.122 for EGC sizing

[pv_n00b]

There is an interesting note attached to table 250.122 that says:

Note: Where necessary to comply with 250.4(A)(5) or (B)(4), the equipment grounding conductor shall be sized larger than given in this table.


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Cooper has an interesting paper on protecting the EGC here: http://www.cooperindustries.com/con...ductor_Protection_Wire_Cable_Protection_1.pdf

Outside of upsizing the EGC when the associated current carrying conductors are upsized for some other reason has anyone found a reason to upsize the EGC?

 

[JoeStillman]

Outside of upsizing the EGC when the associated current carrying conductors are upsized for some other reason has anyone found a reason to upsize the EGC?

Not me.

Interesting paper. I think that if the "code-minimum" sizes really were inadequate, we'd have heard some anecdotes about the times a fault burned up a ground wire. Maybe we haven't because EGCs get involved when the fault is at the load end of a branch circuit, where the available fault current is smallest.

 

[highlegdelta]

They suggest upsizing the EGC to 2/0 but ignore the size of the circuit conductors. 250.122 explicitly states that the EGC does not have to be larger than the circuit conductors. I'm surprised they focused on the EGC rather than also upsizing the rest of the conductors.

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