Ground Wire

A

Alwayslearningelec

Senior Member
Location
NJ
Occupation
Estimator
Doing an analysis to go from MI cable to EMT w/ RHW 2 hr rated cable. The MI has no ground listed e.g 3#6 or 4#3/0 etc.

So now when I swap for conduit/wire I need to include the ground( conduit is not allowed to be used as EGC). The ground should be sized according to breaker size?

Also, would I know it's a different wiring method but I be safe using same size conductors as shown for the MI for the EMT/RHW install?

Thanks.
 
Alwayslearningelec said:
Doing an analysis to go from MI cable to EMT w/ RHW 2 hr rated cable. The MI has no ground listed e.g 3#6 or 4#3/0 etc.

So now when I swap for conduit/wire I need to include the ground( conduit is not allowed to be used as EGC). The ground should be sized according to breaker size?

Also, would I know it's a different wiring method but I be safe using same size conductors as shown for the MI for the EMT/RHW install?

Thanks.
Click to expand...
Why is the conduit not allowed as an EGC ??
The EGC should be based on 250.122..normally breaker size but adjustments may be necessary for increased conductor size.
 
Alwayslearningelec said:
So now when I swap for conduit/wire I need to include the ground( conduit is not allowed to be used as EGC). The ground should be sized according to breaker size?
Click to expand...
Yes the size of the Mi cable is irrelevant. You're designing the feeder for a different wiring method. Your "ground" or EGC for the feeder is sized according to 250.122 as Augie stated.
 
All are correct, it's sized per table 250.122. But you must use the same wire as the power ones per 728. You can't use a bare ground or normal building wire for it. 728 will allow you to use normal wire "if the system allows it", but no system allows it, so you have to use the same wire type as the ground. You can use the steel conduit if allowed locally, but if not, then you're stuck using the fire rated wire for it.
 
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