Alternator safety -a thought.

[sahona]

Lying awake at night, odd things go through your mind...
I changed my alternator from the original Lucas with 6 diodes and external relays/regulator, for a modern higher power version from the scrapyard, a few seasons ago.
The thing I may have overlooked, though, is the fuse in the negative return circuit.
It's a common thing to find on older boats, but could it be a problem now, for if it blows, or has a bad connection, it effectively disconnects the batteries and could then blow the rectifiers, as the alternator would still be self-energised.
In the old circuit, as soon as the fuse blew, the relays would drop out and thus protect the alternator from itself. Lots of boats may have this potential problem - if they have isolated negative to protect the engine from electrolysis, and a new alternator.
My real problem will be to remember the removal job needs done next time I'm at the boat.