circuit breaker not tripping

[Ross Gard]

I am trying to figure why my nav. light doesnt trip? Last week took some green water over the bow, shorting and frying about 2 mt. of insulation of fwd. nav. light. Salt water arced the globe terminals. The globe is ok, the switch still operates the light(after rewiring) But the circuit breaker should have tripped, which it didn't.
So how do I test breaker, without putting screwdriver across terminals? The switch has 5 amp breaker.
The switch/breaker looks to be old enough to be original Ben. rocker switch.

 

[Sailvayu]

Often a partial sort like yours will not trip the breaker this is how fires get started, a short that is not full enough to trip the breaker but will still cause heating in the wires. You could find a load larger than say 8 amps and see if that trips the breaker. A dead short would do it as well but not let you know if it is tripping too slow or not. My guess is this was just a case of a partial short and just not enough to trip the breaker, try to seal the lights and keep an eye on it

 

[Ross Gard]

Thanks Wayne, I have since siliconed where water coming in, so hoping that will fix it, will keep an eye on it too. But don't want to try green water over the bow to see if problem is rectified. Regards Ross.