Update: I consulted with other electrical engineers. Here is a plausible mechanism. Again refer to the circuit diagram of this GFCI:


Look at the board layout. There is a long trace from where C3 is located to the SCR gate. It is suspected that transient capacitive coupling (within the circuit and not from outside) to the SCR gate is the cause.

Suggestion is to try putting C3 directly at the SCR gate, and a 100 ohm carbon comp resistor in place of the trace. This creates a low pass filter at the gate input and also reduces the capacitive coupling to the gate.

The inductive kick at either turn on or off may be the source of the transient.

The series resistor ln combination with the shunt capacitor to the gate is to reduce transient voltage at the gate.


(Original Message)

Does anyone own any Leviton GFCIs (those models without any automatic monitoring self test)? I found out the shaded pole motors from Waterpik can constantly trip on them (50% of the time), but not other brands of GFCI (which I just tried). Someone in the following url has similar experiences with his Leviton GFCI and even a second new Leviton he bought.


So it may not be problems with the normal working of a GFCI but particular implementation of the Leviton GFCI. Anyone got a clue what is that mechanism that can cause shaded pole motors to trip on the Leviton GFCI?

The youtube video describes the shaded pole motor in the Waterpik in details. https://www.youtube.com/watch?v=PmNcRsxSovs

To recap. Even if the plug is 2-prong (without any grounding and it's put on glass surface). The Waterpik motor can trip any Leviton 5mA GFCI (I tested 4 Leviton GFCI outlets) even when isolated and not wet (even if rotor removed). The trips occur either during startup or turning off. Not when it's already on.


In other motor/GFCI combination. What is the reasons why it could trip during startup or turning off. It's not wiring problem. There are many reports of this everywhere. Have you experienced or read about it? What is the mechanism for the constant tripping? (supposed it's not wiring problem which I'm sure it is not in the waterpik motor and Leviton?

You may have heard of new refrigerators tripping on new GFCI. It could if the GFCI is a Leviton brand.. which may not be compatible with refrigerators. I have new refrigerator that also trips every few hours on the Leviton GFCIs. I'm testing it with other GFCI now. Please share your experiences about this too.

2 Answers 2


Anytime you plug in any appliance and it trips a GFCI the odds are that the appliance is not working properly. The easy test is to find another GFCI in somewhere like the kitchen and plug in your unit and see if it trips the device. I really can't speculate why the waterpik is tripping the device but you might see if any moisture is getting into the electrical area of the device and open it up and try to dry it out. Otherwise I recommend that you just replace it or return it under warranty.

Good luck

  • 1
    I agree waterpik are simple motor driven water pumps, if some water has leaked inside that could be enough to cause the problem, or the gfci is failing, try another gfci outlet if it still trips I would open it up and dry it out and try again.+
    – Ed Beal
    Jan 5, 2019 at 20:17

Current normally uses two paths: hot and neutral. GFCI trips require a third (abnormal) current path. If the plug on this unit is 2-prong, then the only possible third path was through you. The GFCI has been saving your life.

There is no radiant leakage. Motors leak current when their insulation is roached, or when water starts leaking internally into places it does not belong.

Sometimes pumps are 100% sealed, with the motor inside the pump so there is no spinning shaft seal, only two easily-sealed wires going in. That, along with cheap Cheese manufacture in value priced consumer appliances, is a recipe for a ground fault after a year or two.

If the product is made in a way that makes it friendly to teardown, you can give that a try and look for any obvious damage. Pumping water is a hard duty for a motor. Pumping water in a $99 consumer appliance is harder duty.

  • please see edited post for the teardown and all the added details.. why does the stator trip?
    – Jtl
    Jan 6, 2019 at 4:48

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.