Grouding for sub panel

[newspark80]

Looking at replacing two Zinzsco panels in a single residence. 200 amp Service currently comes in and serves (2) 100 amp panels. Power comes into a 200 amp fused disconnect. Leaves the knife switch enclosure straight to (1) panel and the other hits another 100 amp fused switch before leaving to hit the other panel.

Question:

There is a 1 1/2 emt conduit that runs through a finished ceiling in the basement. (2) #2 cu line and (1) #2 grounded conductor. No ground. I know I can get away with the conduit as the grounding for branch circuits but can not find if this is legit for 100 amp sub panel.

Thanks!

 

[infinity]

The EMT is fine as the feeder EGC.

 

[kwired]

There is no overcurrent protection limitations. I think to some extent you can kind of figure if higher overcurrent protection is needed then larger conductors will be necessary, also meaning larger raceway will be necessary which increases current carrying ability of the raceway in the event of a ground fault.

 

[newspark80]

There is no overcurrent protection limitations. I think to some extent you can kind of figure if higher overcurrent protection is needed then larger conductors will be necessary, also meaning larger raceway will be necessary which increases current carrying ability of the raceway in the event of a ground fault.

I was going to install a 200 amp main breaker panel with a 100 amp breaker to feed the other main lug panel that I would install to replace the old panel. I will not be adding anything to the panels so no need to run larger wire. Not sure if I am following your line of thinking. Am I missing something?

Thanks

 

[kwired]

I was going to install a 200 amp main breaker panel with a 100 amp breaker to feed the other main lug panel that I would install to replace the old panel. I will not be adding anything to the panels so no need to run larger wire. Not sure if I am following your line of thinking. Am I missing something?

Thanks

Bottom line to what I said is bigger raceway means more cross sectional area of material composing the raceway, which also means more CSA for the EGC if the raceway is the EGC.

Larger ampacity circuit will require a larger minimum sized raceway. So if you were to run absolute minimum sized allowed conductors for a 100 amp circuit then you would have a smaller raceway (and smaller EGC) than if doing same for a 200 amp circuit. By nature the size of the EGC kind of takes care of itself when running larger capacity circuits.