Fuses made from copper strip

Aug 11, 2016 2 Replies

Looking through my bits box for a few fuses and holders for a 40 Kw alterna tor I use for 3 phase in my workshop, I was looking for some over 50 amps i n case anything went wrong with any of my machines. I found 3 which look ab out right but they are just a strip of copper 2 and a quarter inches long a nd half an inch wide clamped into a suitable holder. As a guess I would say they would probably blow at a bit over 50 amps. The thickness is, as far a s I can measure it on my caliper is 1/32nd of an inch



Does any clever chap know how I can calculate the current capacity from the se measurements and so adjust it by cutting the strip in half, for example.



These 3 phases will be for fusing 3 separate 13 sockets but if I just put t hem in the lines they will also protect the outlet on 3 phase devices too.



I suppose I could just hook an ammeter in line and a heavy duty variac, whi ch I have and just wind it up till it blows, but I do not have an unlimited supply of the copper strips and it is not very scientific, is it?



Anyone got a clue? Thanks George.



Are the holders enclosed? sounds like a sizeable amount of copper to spray around if it goes pop ...

As a starter, this calculator

reckons you need 0.42 mm^2 of copper for a 50A fuse, which sounds small to me, but would make your strip over 20x the required CSA.

Another site seems to give same ball-park sizes, so maybe it's not to small

50 amp fuse wire is 21 guage or.721mm dia or .412 sq mm the copper you have would be hundreds of amps.

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