20 Amp Circuit Trips


Old 06-07-04, 07:33 AM
Thread Starter
Join Date: May 2004
Posts: 87
20 Amp Circuit Trips

Why would a newly installed 20 amp circuit trip when running an air compressor (nothing else on the circuit), but a circuit originally installed during construction (about 13 years ago) cary the air compressor?

P.S. Don't know that it matters, but the new circuit is one of those double circuits (2 20 amp circuits in the same space as a larger single 20 amp circuit).

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Old 06-07-04, 07:38 AM
Join Date: Sep 2003
Location: Central New York State
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Not all circuit breakers are created equal.
Old 06-07-04, 10:42 AM
Join Date: Dec 2003
Location: Minneapolis, MN
Posts: 80
It could also be that the new breaker is working as it should, but that the pressure-relief valve on the compressor isn't functioning properly.

A compressor have a very high surge current draw on startup. Yor breaker should be able to cope with the normal surge level, but if the pressure relief valve isn't functioning correctly, and the compressor motor is trying to start against part, or all of the pressure in the tank, the surge levels can be much, much higher.

The way to check this is to completely depressurize the tank, and then try starting up the compressor. If it works, then you have a problem with the valve. If it still trips the breaker, then either the breaker is weak, or the compressor motor is drawing way more than it should for some other reason.

ALso, re-check all of the connections on the circuit wires (even ones you don't think you disturbed) and make sure they're tight and solid.
Old 06-08-04, 08:17 AM
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Join Date: May 2004
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I appreciate the responses.

Old 06-08-04, 04:27 PM
scott e.'s Avatar
Join Date: Jun 2003
Location: Anderson, IN
Posts: 412
I assume the compressor is 120V?

Scott E.

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