Circuit breaker

[trapper]

1987 lt30 16hp briggs engine the start position on the key switch fails every couple years.  Added a separate start switch directly from the battery. 8 ft 8 gauge wire. What size circuit breaker  do I  need 

 

 

[Joe Hillmann]

I don't think starters usually have fuses to them.    The best method would be to measure the amps with a clamp on amp meter.  That may be an expensive tool to use only once though.

What is the cranking amps of your battery?  All a fuse on the started will protect is against a dead short so I would put something 1/2 to 3/4 of the cranking amps of your battery.

[trapper]

that is what i want to protect against a dead short

[Den-Den]

A starter is very close to a dead short, you would be better off to use a small fuse or breaker sized for other electrical loads (if you have any) and bypass the fuse / breaker with the starter solenoid.

[trapper]

  den den that is what I did

[Magicman]

If you are using the key switch to energize the starter without a start relay/solenoid, that probably explains why you are burning up key switches.  The key switch needs to operate a "slave" relay which actually supplies the 12vdc to the starter.

[ladylake]

 If you have a heavy enough switch, maybe 200 amps or so I dont think you need a breaker, You'll know right away if something is wrong in the starting circuit .  Steve

[mike_belben]

What MM said.  If your switch is engaging a starter solenoid your load is simply the magnetism to pull the solenoid.  


If youre running the starter its the full load cold cranking amps.  Either way your relays, breakers and fuses are only sized to protect the wire itself from igniting.  The wire gauge, length and voltage is looked up in a chart.  The right fuse for the wired protection may not be sufficent if you are direct starting through the switch.  



Unfortunately universal ignition key switches have gone to absolute crap.  I cannot find any that are american made on a shelf in any store and dont ever get a year out of them.  20+ yr old junkyard switches ive repurposed never miss a beat.   Foreign junk..

Highway CHI-way robbery. 

[trapper]

Mike you  hit the nail on the head.  That is why I went direct from battery to manual starter switch to starter.     Heavy contact momentary spring loaded switch.

[mike_belben]

If this one fails use a $20 ford style starter solenoid.  Chassis needs grounded and the left lug gets triggered 12v to make it crank.