12 volt circuit breaker

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rds912

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Mar 13, 2016
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I want to add a main circuit breaker and battery cutoff switch at the battery box.  Can anyone suggest what size circuit breaker I should use.

Thanks
 
Lots of questions. Does this battery or batteries start a vehicle? If it does, is it gas or diesel? Expected cold climate start? Cold cranking amps of battery? Just an example, the last bad 460 ford starter I replaced was pulling 400 amps on a warm start. Replacement starter pulled 90 amps warm. Should be able to google your starter specs. If battery for TT, I guess you just add up amps of all expected usage and add 10-15%? I'm not an electrician but l'm sure the knowledgeable ones will chime in.
 
My 2,000 watt Magnum inverter specifies a 250 amp breaker or 300 amp time delayed fuse between the battery bank and inverter.
 
Ok. Well I was way off then. It's a tt 30 amp service ac,  dc 2 batteries.  I was thinking of going just higher than the biggest fuse.  Didn't even think about adding them all up.
 
Don't add up all of the fuses.  The main fuse or circuit breaker protects the wire between the battery and the fuse center, so it's capacity is determined by the size of the wire.  What gauge is the wire going to your battery?
 
Hopefully both the wire and the fuse will be sized big enough to deliver the combined max DC amp load, but Lou is right that the fuse should not be rated larger than the wire can safely handle. The wire ampacity is basically a matter of wire gauge and, to some extent, length.
 
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