Three-way switch & GFCI

[Doug]

Hi and thanks for any help.

I just pulled out a standard outlet in our bathroom to replace with a GFCI. Got the GFCI in fine. However, apparently the load side powers our hallway's three way switch (which has there separate switches) and then runs into a bedroom and provides lighting there.

Whenever I turn the hallway light on it trips the GFCI. The lights farther down the line don't trip the switch, just the three-way hallway lights. Is this expected or is there a problem with the hallway lighting?

Doug

[RBM]

It shouldn't trip unless there is a ground fault. There is no requirement to have the wiring outside of the bathroom outlet,protected by the gfci.

[Terry]

Your electrician has incorrectly wired the 3 way switches. This condition could cause the screw shell of the lamps to be hot under certain conditions.

One way to get help is pull the switches out and take pictures or pull the switches out and assign each cable a number.

Switch 1 B1 w1

b2 w2 r2

switch 2 b1 w1 r1

[John Grabowski]

No it is not expected. It seems that there may be a problem with the hallway lights. After you get it corrected you can remove the lighting feed from the load side of the GFCI unless it is also protecting a shower light or shower fan or another bath, garage, basement, or outdoor outlet.

[Wayne Whitney]

I believe the NEC requires that the circuit serving a bathroom receptacle either (1) serves only bathroom receptacles or (2) serves only loads in that bathroom. So you need to run a new circuit for the downstream loads, in addition to investigating how the downstream loads are miswired.

Cheers, Wayne

[bud--]

Only required for new circuits.

My guess is that the light that is on the 3 way switches connects to the neutral on another circuit, but it could be something else.

[Wayne Whitney]

You don't believe that changing a receptacle out would cause the requirement to come into force? I thought it might. In any event, it would be good practice to comply.

Cheers, Wayne

[RBM]

It certainly wouldn't come into force. The guy decides, for his safety, to install a GFCI where one didn't exist, and you think the NEC wouldn't allow it unless he completely upgrades to current standards. That would be ludicrous

[Wayne Whitney]

OK. Wayne

[terry]

AIUI what actually trips a GFCI is an unbalance in the current between the currents flowing through the live and neutral wires beyone (downstream) of the GFCI. While agreeing that it is not necessary that the lighting circuits be fed 'through' the GFCI, it would appear advisable, instead of looking for a 'ground fault', to look for the possibility of miswiring or at least an 'oddity' of the 3 way switch and lighting.

[RBM]

No question bout it, and I think Bud probably nailed it. If there are multiple circuits involved, sometimes neutrals from different circuits can get tied together in multiple switch boxes, in fact I'm sure that I've inadvertently done it myself. This would cause the GFCI to trip

[Doug]

Thanks a load for all the responses. As a temp fix to allow light in the hallway I wired the load & line sides through the line side of the GFCI. I'm not comfortable doing more than replacing outlets/switches myself so I'll have an electrician out to determine the problem and solution. I just wanted to know if it was something I should be concerned about.

Doug