We have a simple circuit that consits of a line (feeder?) at 480v, and a parallel circuit, we'd call a branch, with a low SCCR. My understanding is that SB4.4.1 does not allow you to consider the current limiting capabilities of a current limiting fuse when it's located in a branch. I've been told this by 2 separate people from UL. I think if you read SB4.4.1 you might be able to get that from the text but it certainly doesn't say it in plain terms. Can some verify that this understanding is correct? Effectively, it means that you need CL protection ahead of a CL fuse in a branch. Or in our case, truely redundant fuses. Why have they denied the ability of a CL fuse to limit current just based on it's location in the circuit?
Neil
Neil