Battery Kill switch and Main Circuit Breaker

mistertwister87

Seaman Apprentice
Joined
Aug 10, 2011
Messages
32
I just noticed I do not have a battery Kill switch or Circuit Breaker on my Boat (Alumacraft Phantom). It does have a fuse panel though. Do I need both of these? I am thinking I do after reading some of the posts here. Any suggestions on what size circuit breaker? I like the idea of a battery kill switch so I can just cut off the power when in storage in case a depth finder or radio were left on. Any thoughts on this?
 

Silvertip

Supreme Mariner
Joined
Sep 22, 2003
Messages
28,758
Re: Battery Kill switch and Main Circuit Breaker

The breaker goes at the battery and if the wiring to the fuse panel from the battery is #8 or #10 a 30 amp breaker is sufficient. That breaker by the way protects the run of wire from the battery to the fuse panel. The fuses in the fuse panel protect the run of wire from the panel to the device. Fuses DO NOT protect equipment. If something happens in the equipment that causes a fuse to blow, that equipment is toast anyway. The battery switch is a good idea and they are cheap (when compared to everything else on a boat.)
 

MH Hawker

Vice Admiral
Joined
Jul 13, 2011
Messages
5,516
Re: Battery Kill switch and Main Circuit Breaker

A battery switch is a very good idea for many reasons. It stops any battery drain that can be due for many reasons. When servicing the motor or electrical system its a lot simpler and easer to switch it off than taking off battery terminals and much safer.
 

mistertwister87

Seaman Apprentice
Joined
Aug 10, 2011
Messages
32
Re: Battery Kill switch and Main Circuit Breaker

Thanks guys. I really appreciate you taking the time to answer my questions. I will pick up both items and install. Silvertip, what if the wiring going to the fuse panel is 14 or 16 gauge? What size breaker would that require?
 

Silvertip

Supreme Mariner
Joined
Sep 22, 2003
Messages
28,758
Re: Battery Kill switch and Main Circuit Breaker

Thanks guys. I really appreciate you taking the time to answer my questions. I will pick up both items and install. Silvertip, what if the wiring going to the fuse panel is 14 or 16 gauge? What size breaker would that require?

If the wiring going to the fuse panel is 16 gauge it is too small. Remember, that wire must carry the current load for EVERY item fed from the fuse panel or any positive bus fed by that wire. If you have everything turned on at once and the total current draw is 15 amps, the 16 gauge wire will melt. 14 gauge wire would also be too small as it is rated for 15 amps. That run of wire should be at least #12 and preferably #10 so there is some margin. I cannot believe that boat was wired originally with a 16 gauge or even 14 gauge house circuit. If it is 16 gauge, a 10 amp fuse is max. If 14 gauge, then a 15 amp fuse is maximum. A battery switch connects to the positive terminal of the battery. The large battery cable connects to the other side of the switch along with the fues for the 14 or 16 gauge house circuit.
 

mistertwister87

Seaman Apprentice
Joined
Aug 10, 2011
Messages
32
Re: Battery Kill switch and Main Circuit Breaker

Thank you. I am not sure what size wire it is, just wanted to ask just in case. I am going to look into this tonight. I am a novice on these things, so I do appreciate your help.
 
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