Class C GFCI as per UL 943C

[mshields]

Trying to bone up on GFCI over and above the run of the mill Class A type. The article I'm reading says that Class C is "for use in circuits with no conductor more than 300 V to ground (i.e.,
systems where line-to-line voltage is 480 V or less) where reliable equipment grounding or double insulation is provided."

OK - so for practical purposes, this targets 480Y/277V circuits, but here are my questions:

GFCI is different from the ground fault we are required to provide on 1000A and above feeders correct. Are circuit breakers available with Class C GFCI or do you have to provide separate protection. Where would that typically be located? I'm guessing it comes with the equipment and that it's mostly an OEM concern. True?

 

[mshields]

one more question

one more question

and what is this thing about "double insulation"? If you were using for example THHN/THWN, what would you use for double insulation?

 

[GoldDigger]

Double insulation refers solely to the load, i.e machine or appliance, since that is where the personal safety hazard is. That level of protection is not needed for wires inside raceways.

mobile

 

[Jraef]

I don't know of any circuit breakers on the market yet that are UL listed as Class C GFCIs. It's one of those things that happen where a testing authority like UL comes out with a new rule, but it doesn't apply to anything that's on the market. They did that with AFCIs too.

Right now the only way you can get a listed Class C GFCI is through people like Bender and Littlefuse that sell them as "systems" consisting of their detector and a contactor. You can't build them on your own though, they have to be listed together by UL.

You can get plenty of circuit breakers with adjustable solid state Ground Fault trips that can go anywhere from 10-300ma (Class C is 20mA), but they are EQUIPMENT ground fault protective devices, not UL943 classified. That's because the breaker reaction and opening time is not fast enough to meet that UL requirement. Sooner or later someone will do it, but not yet that I've heard of.

 

[mshields]

GFEP

GFEP

How about the 20mA GFEP protection we use for heat trace?

That I assume is not class C because it may be 120V; class C has a specific voltage window. Correct?

What UL standard covers this type of ground fault protection?

Lastly, do Classes D and E, covered in the UL943C standard also fall into the category as being something that exists only in the minds of the people who wrote the standard?

Thanks,

Mike