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Hi there,

Looking for a bit of clarification here.

My house bank for the time being is a single deep cycle 12V battery, CCA of around 660, with 15feet of GA 1 cable leading to a battery switch, and a further 4 feet leading to a 100amp breaker on the main panel.

Do I need to put a fuse within 7 inches of the battery connection? Or will the main 100amp breaker protect me? Each branch circuit has its own breaker as well. I have a dedicated start battery that is fused according to the Blue Seas OC protection chart.

Along the same lines, I have two bilge pumps, the 'oh ****' one is permanently wired to the battery and draws 4amps, and I've stuck a 5amp fuse on there next to the connection to the battery.

The other, smaller bilge pump (2amps) is wired to the panel which has a 15amp breaker in there - again, do I need to add a small (3ampish) fuse to near the pump? Or is the breaker enough protection?

Thanks for any help!
 

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Hi there,

Looking for a bit of clarification here.

My house bank for the time being is a single deep cycle 12V battery, CCA of around 660, with 15feet of GA 1 cable leading to a battery switch, and a further 4 feet leading to a 100amp breaker on the main panel.

Do I need to put a fuse within 7 inches of the battery connection? Or will the main 100amp breaker protect me? Each branch circuit has its own breaker as well. I have a dedicated start battery that is fused according to the Blue Seas OC protection chart.

Along the same lines, I have two bilge pumps, the 'oh ****' one is permanently wired to the battery and draws 4amps, and I've stuck a 5amp fuse on there next to the connection to the battery.

The other, smaller bilge pump (2amps) is wired to the panel which has a 15amp breaker in there - again, do I need to add a small (3ampish) fuse to near the pump? Or is the breaker enough protection?

Thanks for any help!
Fuse needs to protect the battery cable within 7" or as close as you can get it to the + battery terminal. The 100A breaker will do squat to protect you if a short occurs before it..... If you have the possibility of starting the motor from this bank then the fuse should be sized to handle the starting loads, which is going to require at least a 200A fuse, for most small AUX diesels, but preferably 250A...

Bilge pumps require two fuses. One close to the battery (within 7") to protect the wire then one at the bilge switch rated to NEVER exceed the manufacturers specified size, unless of course you want to start a fire if the pump stalls from debris...
 
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