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Larry Larry is offline
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First recorded activity by BoatBanter: Jul 2006
Posts: 5,275
Default Circuit breakers/fuses in parallel

Herodotus wrote in
:

However wait a while to see if Larry blows me out of the water and
proves me wrong.

Larry????

cheers
Peter



Paralleling them is fine AS LONG AS the wire they are protecting can
bear, safely, the whole amp load two breakers can produce. Most boat
wiring is way too light away from the starting circuits. Sure hope you
got big batteries!

I'm having great luck on DC circuits using automatic-resetting thermal
breakers GM puts in their crappy cars....or did until the plants
shutdown. They have high amp little plugin breakers you can buy at NAPA
and the sockets they plug into..

Of course, this won't do on most boats that don't have a DAMNED SWITCH
and wear out the breakers using them as switches....

The little breakers are really tiny and mounting them is really
easy....and cheap. I'm using them as branch circuit protectors on the
very heavily wired primary electronics bus, which uses a continuous-duty
12V contactor with lighted switch as a master disconnect to shut down
the whole electronics suite in all compartments from right by the hatch
with a bright red light (night vision cabin lighting) so my captain
doesn't go off and leave the whole boat running for weeks.

I put the branch breakers, which don't require a manual reset but reset
themselves in about 10 minutes in the heat, where the branch circuit
comes off the bus, whereever that may be (helm, nav, cockpit, etc.)

For 30A, I'd want to use #8 for short runs and #6 for long runs, up to
the bow for instance. As the sooper-dooper marine wire is just plastic
covered wire, I use the heavy speaker wire Radio Shack carries. When
the main warehouse store closed here, I bought it all, a lifetime
supply, for about 10c/ft...(c; My shed is full of it on big spools...a
lifetime supply.