Quote:
Originally Posted by CousinEddie
… 2 circuit breakers in series. … mounted to the frame at the front and is fed directly from the battery, I'm assuming it's 30 amp.
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Wire Size Determines Maximum Breaker Size
My Kodiak Cub has a 40 amp breaker there. It is a self resetting breaker like yours,. It protects the battery wire and provides power to the emergency electric brake should your TT become separated while moving.
1) What size is the wire to the battery from this breaker. Wire size is the key to breaker or fuse size. Load capacity and charging capacity are important, but wire size determines the maximum breaker size.
My Cub has a 6 AWG wire with a 40 Amp self resetting circuit breaker. It connects the emergency electric brake and 7 pin tow vehicle connecter. It originally also connected to the TT 12 volt converter. I installed a separate 50 amp manual breaker. It connects the battery to the TT 12 volt service. It delivers 50 amps through about 20 feet to the TT 12 volt converter unit when my 120 volt inverter is running and it is used to disconnect the battery when shore power is connected for long periods.
12 volt wire tables:
6 AWG is good for 50 amps up to 28 feet.
8 AWG is good for 50 amps up to 16 feet
8 AWG is good for 40 amps up to 28 feet
10 AWG is good for 40 amps up to 16 feet
10 AWG is good for 30 amps up to 24 feet
12 AWG is good for 30 amps up to 16 feet
The max distances are for both load and charging purposes. Using larger wire is sometimes used to reduce line loss and raise voltage at the far end.
Warning! Do not use these values for AC wiring such as 120 volt. Larger wire sizes are needed for AC circuits.
"inside of the junction box for the 7-pin harness connections labeled 40 amp. EVERYTHING in the 12 volt system is fed from the 40 amp breaker."
I assume the 7-pin harness is the connector to the tow vehicle.
1) Is the 40 amp breaker a self resetting, or manually controlled? If it is manually controlled, it can be used as a battery disconnect switch. It may have been installed to prevent "boiling" the battery during long periods of charging from shore power. In this case it is not the 40 amps that is important. It is the manual switching capability.
2) Are you sure the electric brake emergency activation switch is not connected near the 30 amp breaker?
Assuming nothing is on the 30 amp breaker side as you stated and the 40 amp breaker is manually reset, you should move the electric emergency brake switch wire to the 30 amp side so it will activate even if the 40 amp breaker is off.
" I can post pics if that would be helpful"
Posting pics would help greatly.
Paul Bristol