Strange Motor Problem Instantly Trips Breaker When Plugged In

[willf650]

There may be something wrong with your unit. But with what you described you have the hot and neutral crossed in your cord setup would be my guess as a starting point.

There should be no path for the current and gfi to trip if the switch is off unless you have wires crossed.

 

[Cruzan80]

Can someone explain how, with his switch OFF, it's still tripping the GFCI?

If the switch is single-pole, and switching the neutral, not the hot, then he could be losing current to ground past the switch (either broken wires inside the yellow cord, or in the motor itself). That would trip the GFCI, even with it "off". It could easily be low enough that his meter didn't catch it, depending on what mode he was in (no load=phantom readings)

 

[Maui]

Given the second unit has a black wire coming out of the motor, it means that all you have identified is that from the white round plug onwards is good. Anything from the yellow prongs back on the first is suspect.

It could be the yellow cord is miswired, broken inside, or a bad connection inside the motor, or grinding dust, or... You need to take the meter out of continuity mode and start checking for resistance, etc, just like you would on any other given suspect motor.

There were several questions about the GFCI being faulty as well as the switched power cord that I wired up being incorrectly wired. This one test should demonstrate that this is not the case. The yellow cord is brand new, and has not been miswired.

I will be happy to provide photos of the opened plug as Frank Lee requested.