Self resetting circuit breakers for relay harness?

I believe I read from Virgil that fuses only are the safest option for a relay harness. Searching again yields no results(probably user error).

Are self resting circuit breakers a safety hazard? If so, is it because they could constantly send brief fault current while unattended Or that maybe they aren't precise? I am curious as to pros and cons, my initial feeling is that a fault may be momentary and then lights could be restored in an instant, but constantly faulting while the truck is not attended makes me doubt my impression.

thank you all for your replies

Kenny78 said:

I believe I read from Virgil that fuses only are the safest option for a relay harness. Searching again yields no results(probably user error).

Are self resting circuit breakers a safety hazard? If so, is it because they could constantly send brief fault current while unattended Or that maybe they aren't precise? I am curious as to pros and cons, my initial feeling is that a fault may be momentary and then lights could be restored in an instant, but constantly faulting while the truck is not attended makes me doubt my impression.

thank you all for your replies

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I've never heard of using self resetting circuit breakers in a lighting harness and wouldn't recommend it myself as I think mostly the self resetting breakers are for certain motors which typically at times can have high current startup like windshield wipers. Typically if you have a fused lighting wiring harness and it trips you need to fix the problem as typically either you have a short or you have the wrong size breaker. I've made several relay wiring harnesses and never tripped the fuses on them using horns and lights when I had the proper sized fuse on them.

Lynx Arc is exactly right. Never use self-reset circuit breakers in a lighting circuit; it's unsafe. With lights either your circuit works or it's faulty; you won't get a temporary/transient load exceedance. If you use a self-reset breaker, you're going to keep shooting power through a faulty circuit on an intermittent basis until the fire starts. No, you want the faulty circuit to go dead and stay dead until it's fixed. That means fuses or manual-reset circuit breakers.

Lynx_Arc said:

wouldn't recommend it myself as I think mostly the self resetting breakers are for certain motors which typically at times can have high current startup like windshield wipers. Typically if you have a fused lighting wiring harness and it trips you need to fix the problem as typically either you have a short or you have the wrong size breaker.

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Over in one. A headlighting circuit is a predictable resistive load; exceeding the load means a closed short somewhere. Could you use one as a troubleshooting method while in the driveway and wiggling wires around to see what's causing it? Perhaps. But leaving one permanently installed? Nope. That's asking for a lot of trouble.

Alaric Darconville said:

Over in one. A headlighting circuit is a predictable resistive load; exceeding the load means a closed short somewhere. Could you use one as a troubleshooting method while in the driveway and wiggling wires around to see what's causing it? Perhaps. But leaving one permanently installed? Nope. That's asking for a lot of trouble.

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Exactly. It would be better to check across the blown fuse how much current is going through the circuit to get an idea of if it is truly shorted or the "normal" load on the lighting harness is either too close to the fuse rating or exceeding it.

Thanks for all your thorough responses. I appreciate it.