Auto transfer generator panel loudly humming


Old 09-17-15, 10:07 AM
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Auto transfer generator panel loudly humming

Hi I have an auto transfer generator. It is wires next to all the house circiut breakers in the basement, except the main power connect, which is in the garage. When all of the house circuit breakers are off the panel continues to hum really loudly ( the generator is of course off) why is doing that? I assume something is drawing power, but what would draw power and not be connected to the circuit breaker panel? And how do I find it?
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Old 09-17-15, 10:43 AM
Join Date: Oct 2005
Location: USA
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These auto switch panels have solenoids in them that are energized even if your main panel is off. In fact, your power comes to the transfer panel before it hits the load center. My 200 amp generac auto switch is dead quiet.
DO you have one of these?
Old 09-17-15, 09:40 PM
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Welcome to the forums.

Although, like telecom guy mentioned, the transfer switch is wired before the house panel it should be quiet. Depending on the brand..... most don't use an "always active" solenoid.

A real loud hum could be caused by a problem control relay.
Have you tried a transfer to the generator to see if it changes ?

You could post the make of the transfer switch or generator system. A model number of the transfer switch would even be more helpful.

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