Burnt 12V Switch

[rcamaine]

Was making a checklist of things to work on - fairly long list (1980 Tri-Cabin) - and I was testing the forward head vent fan. I had turned on the three vent 12V switches on the main 12V panel.

After a bit - maybe 30 minutes - I smelled smoke! Saw some smoke and a burning smell coming from the 12V panel. I cut the two main battery switches and unscrewed the panel.

While the panel was off - I flipped on first battery number 1 - no smoke. Flipped on battery 2 and sure enough smoke - coming from the switch to the galley fan.

I ended up pulling the switch out - picture below. I knew the galley vent did not work - but it must be one hell of a short somewhere in that circuit to cause this switch to melt! There is evidence of quite a bit of water leaking in the lower part of the galley as the wood is quite rotted - right along where that vent is located under the cupboard.

My question is this though - are the two 12V DC Main swicthes circuit breakers or just big switches??

I was surprised that a switch would melt without a breaker tripping - if in fact they are breakers.

For saftey sake - should individual fuses be put in line that could perhaps stop this from happening? Any ideas appreciated! Thanks, John.

PS - I always make sure these two DC Mains are OFF when I leave...

[akwalker]

Maybe the circuit is protected by a fuse or circuit breaker, but that switch might not be rated for the load?

[prowlersfish]

The mains are switches . that switch that burnt up may in fact be a breaker or should be ( look at the others and your wiring diagram ) high resistance in the breaker/switch could have caused it to burn up

[Big D]

Pretty sure those are supposed to be breakers on the panel unless a previous owner replaced with the wrong hardware. Have you checked to see if the fan motor is siezed? Also, like any other breaker, you should turn them off and on periodically; helps prolong internal hardware life and will sometimes not reset if there is a problem with the mechanism.