Hi,

I've been considering the use of Polyfuses (made by Raychem among others)
instead of circuit breakers in an electric panel on my boat. They are a lot
cheaper (like $0.50 each) and smaller than a breaker. The specs say "100A
maximum current" for a typical 5-10A fuse. This is the maximum fault
current that can be used to trip such a device.

The typical C series Carling hyd./magnetic circuit breaker has a
interrupting capacity of 7500A @ 80VDC. This is the toggle type circuit
breaker that you see on most new boats.

My question: is 100A interrupting enough? If there is a short in a typical
wire, will fault currents exceed that? I don't know enough electrical
engineering to determine if this would be a safe application for these
fuses. I do know of one kit plane builder (who is an EE) who thinks they
are o.k. And one maker of boat parts who is offering them:
http://www.lalizas.com/products.asp?S0=5&S1=13&S2=37

This is a kit plane builder who uses them:

http://www.expbus.com/pages/avionics_expbus.htm


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Evan Gatehouse

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