GFCI question

[chrisrappl]

I have a 2 pole 60a breaker feeding a branch circuit which feeds six two circuit load centers which in-turn feed twelve 5-20 duplex receptacles (one duplex per circuit). I actually have forty of these 2 pole 60a circuits feeding a total of 480 NEMA 5-20 duplex receptacles. The customer is asking about the feasibility of GFCI protection for the receptacles. I could change out all of the receptacles or all of the single pole 20a breakers feeding the receptacles to GFCIs, but I'd like to consider the alternative of changing the 2 pole 60a breakers to GFCI breakers.

Would this physically work?

If so, what would be the ground fault tripping threshold?

I know that GFCI receptacles and single pole GFCI breakers will trip on fault currents anywhere over 4 milliamps.

At what fault current level do the 2 pole 60a GFCI breakers trip?

How would a 2 pole GFCI breaker perform with the neutral current of 12 receptacle loads?

If there is any chance that this might work, I'd like to install one and try it over the course of a weekend.

 

[Dennis Alwon]

Firstly, the wire going to a panel is not a branch circuit but a feeder. Secondly, you could install a dp 60 amp gfci but if there is an issue later it will be hell to troubleshoot.

 

[480sparky]

.............At what fault current level do the 2 pole 60a GFCI breakers trip?........

4-6 ma, same as all the others.

 

[iwire]

I would not recommend doing that.

It is legal, it will provide GFCI protection, I think it will be nuisance tripping.

FPN: Class A ground-fault circuit interrupters trip when
the current to ground is 6 mA or higher and do not trip
when the current to ground is less than 4 mA. For further
information, see UL 943, Standard for Ground-Fault Circuit
Interrupters.