Sizing fuses for overload on a motor 0.78 fla.

[RRJ]

I came across this circulating pump that’s 1/25hp 115v 0.78 fla on a 30 amp nonfuse disconnect and a 20 amp breaker


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[LarryFine]

Typical when taken from an existing circuit. Most motors that small are what's called impedance-protected, meaning the current is low enough that no permanent damage happens even if stalled.

If you want to feel better, replace the disconnect with a small fused switch with, say, a 2.5a fuse.

 

[RRJ]

Yeah, this motor is burned twice already but I don’t think it’s electrical. I think it’s a mechanical problem.


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[ptonsparky]

Yeah, this motor is burned twice already but I don’t think it’s electrical. I think it’s a mechanical problem.


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Most of my calls seem to a mechanical failure first.

 

[Jraef]

When I worked at a steel mill years ago, the main Maintenance Supervisor kept saying to us electricians, “If it fails when connected to electricity, it’s an electrical problem”...

...until we proved it otherwise, which was really about 90% of the time.

 

[RRJ]

I watched a mike holt video where his boat dock lift motor kept burning up and after buying three motors he noticed a bird triggering the lever that turned the motor on and that’s why it kept burning, but he fused it and did not had a problem ever since.

I guess that was my question to fuse a less than 1hp motor or not? I guess it depends on the situation. If you are a maintenance person for that particular facility yes, but if you are a contractor in which case if it burns it’s the plumbers or mechanics responsibility then No.


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[ptonsparky]

Bird...mechanical problem.

 

[ActionDave]

When I worked at a steel mill years ago, the main Maintenance Supervisor kept saying to us electricians, “If it fails when connected to electricity, it’s an electrical problem”...

...until we proved it otherwise, which was really about 90% of the time.

Every conversation starts the same way, "Are you sure it's the motor?"

Every answer is something like, "Yes" or "It has to be, we've tried everything else"

I've lost count of the number of commercial kitchen exhaust fans I've repaired by replacing the fan belt. Tell you what though, I have learned more about pumps, fans, tire machines, saws, ovens, hay stackers, slurpee machines etc, than I ever thought possible. It's been a lot of fun.