Gpgr4blu, I’m sure Tsushima1 is correct about the physical size and voltage rating of the fuses that are required for your ARC gear, but to clarify about the voltage ratings: The 500v and 250v ratings refer to how much voltage a fuse can withstand when it blows. The voltage a fuse will "see" when it blows (i.e., the voltage that will appear between the fuse’s two contacts) will be the full line voltage. So the higher that rating is the better, everything else being equal. Under normal operating conditions the voltage appearing across fuses having these kinds of ratings will be a very miniscule fraction of a volt. And when the component is turned off the voltage appearing across the fuse will be zero.
HOWEVER, I would disagree with a couple of important things that have been said just above:
1)I would strongly recommend against substituting a fast blow fuse of somewhat higher current rating for a slow blow fuse of somewhat lower current rating. Some time ago, in connection with this thread, I looked at the detailed "melting point" specifications that are provided by the major manufacturers of garden variety fuses. That spec defines the approximate combination of current and time that will cause the fuse to blow (actually, in terms of current squared x time, which is proportional to energy). The upshot is that such a substitution stands an excellent chance of causing the fuse to blow almost immediately. Especially in the case of a mains fuse, where brief but very large "inrush currents" may occur at turn-on.
2)Earlier in the thread there were multiple anecdotal indications that the unspecified melting points of SR fuses are probably a bit lower than those of garden variety fuses having the same current rating (i.e., indications that the SRs blow a bit more readily). And it would seem expectable that in general a fault in a component that would cause a fuse to blow is more likely than not to result in a very large current increase, rather than one that is just slightly greater than the rating of the original fuse. Especially in the case of a mains fuse. So for both of those reasons I would suggest using a 6.3A slow blow in a 6A slow blow application, and an 8A slow blow in a 7A slow blow application. And likewise if an SR fast blow is substituted for a stock fast blow.
Good luck. Regards,
-- Al
