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UL question

UL question

UL question

(OP)
I am using a 75VA isolation transformer to power controls for a gate operator.  I cannot find anything in UL325 that mentions the specs for the primary fuse, only secondary requirements....does anyone know if UL cares about the primary fuse or is it just an NEC requirement?  OR am I looking in the wrong place?  There was mention of UL 1585, but I don't think I have a copy of that...

RE: UL question

NEC would govern the fusing in this case.

UL would care only if the fuse is integral part of the assembly being tested for UL listing.

Rafiq Bulsara
http://www.srengineersct.com

RE: UL question

UL508 requires fusing of control power transformer primaries, but UL suggests checking the NEC requirements as well. There was controversy a number of years ago because they didn't agree with each other. Local inspectors, having the final jurisdiction, would sometimes reject what was perfectly acceptable per UL standards. So ultimately, assume the NEC is more stringent and go that way, you will not be violating UL.


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