"Gary Warner" wrote in message
...


The only difference I found is that the
wire from my alternator is not fused prior to the ammeter. Should I put
one in? If so, what amperage?

In general, the fuse/circuit breaker should be sized appropriately to
protect the wiring, not any device on the circuit. The wire should be sized
so that it can carry the maximum output of the alternator with a comfortable
margin. The fuse should be sized so that the fuse blows if the current
should exceed the rating of the wire. You can do a web search to find
tables that provide wire size vs. current capacity.




I don't think a fuse is required there. I just decided to do it on the
"what
can it hurt" theory.


Well, one thing that it can hurt is the alternator!

Fuses can fatigue and fail without their ratings ever being exceeded. If
the fuse opens while the alternator is running at full output and leaves the
alternator disconnected from any load there is a high probability that the
resulting voltage spike will destroy the diodes in the alternator.

Rod