HELP! Compressor now trips breaker on start up??

RustyRatRod said

What "I" would do is un wire the switch. Connect an amp meter to the motor and see exactly what it draws on startup. I can tell you that motor is NOT a true 5HP motor. It will probably be more like 3. But by measuring the start up amperage draw, you can get an idea of the size motor it really is and what size wiring and switch you need.

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Finally, the voice of sanity (go figure).

If it worked before you added the switch....start by removing the switch and any other mods done at the same time.

I agree a true 5 HP motor probably draws way more than 20A (unless it's super, super efficient). Probably closer to 30A.

IIRC the startup draw is a "delta" or close to three times the running draw.

My true 5HP motor is the size and weight of two small block heads and requires 30A and #10 wire.

"AmProbes" are kinda pricey, and finding a 30A capable consumer VOM to put in series might be as well.

You could always install a $10 disconnect box with a 20A breaker near the compressor, and use that.