ECN Forum Forums General Topics of the Trade General Discussion Area Motor GFCI trip

This just started on a 3 year old motor. It trips GFCI on start up. I hooked it to a non GFCI and it works OK. I pup my clamp on it and there is a short 200ma spike right when it starts. I know the short answer is the motor is bad, get a new one but does anyone have any other ideas?

This is a boat lift so running without GFCI protection is a "you bet your life" thing.

https://gfretwell.com/ftp/Lift%20Motor%20GFCI%20Trip.wmv

Maybe replace the start capacitor?

Although tripping the GFCI is not the most common effect of a capacitor fault, and your motor does work without GFCI, there are still some defects that can make a capacitor trip the GFCI (assumes you've ruled out the most common culprits for the problem).

I plan on working on this when it stops raining. I hope it is just water in the motor. I will also look at the capacitor.
My first plan is to just take the belt off and run the motor until it warms up and see if that doesn't just dry it out.

Boat lift motors and GFCI trips on startup — moisture is the usual suspect, and you're already thinking along the right lines. But rather than just running it to dry out, megger the windings phase-to-ground. That will tell you in thirty seconds whether the insulation is breaking down. Anything under a megohm on a small motor like that and you've found your leakage path; running it hot might dry it out temporarily, but deteriorated insulation only gets worse.

Check the terminal box first — it's the most common water entry point, and corroded connections in there will leak to ground on startup when everything's cold and damp. Also have a look at the start switch area while you're in there.

The capacitor theory is a red herring for the GFCI part: a bad start cap keeps the motor in locked-rotor longer, which is an overcurrent issue, not a ground fault. The GFCI is seeing real leakage to ground — the video of it tripping right at startup is classic winding/terminal-box moisture.

And completely agree on keeping the GFCI in the circuit. On a boat lift, "you bet your life" is exactly right — never bypass it to get through the season.

Sometimes a GFCI releases on much lower current than what it is stamped with, and of course you are well protected.
Normally this is not a problem at all, and we don't know about it because it releases when tested.

This is seeing a 100-200 MA spike in the EGC on start up so I am thinking there is a fault in the start windings. It has really been raining every time I get a chance to work on it so I haven't had a chance to meter the windings or tear it down to see if there is a dirt dauber nest in there shorting something out