sharing common for GFCI & other circuit

[powerplay]

When feeding power to an bathroom heat mat with a built in GFCI, would there be any problems sharing the common off a 3 wire circuit such as false tripping?..or for that matter, are there any noticable complications feeding circuits with an 3 wire that have a minor motor load such as a fridge or garburetor?

Thanking you in advance for the feedback!

 

[infinity]

Re: sharing common for GFCI & other circuit

I don't see any problem since the mats' protection is at the end of the circuit. If you were trying to use a GFCI CB on one of the two circuits you would have a problem. I think of it this way, your 3 wire circuit is not different than a 3 wire feeder to your panel. Either way you have a common shared neutral. It's where the protection is in the circuit that matters.

 

[powerplay]

Re: sharing common for GFCI & other circuit

I wasn't sure, but was curious if the GFI would be sensitive to harmonic type feedback from a ballast or the like close to the device, and far away from the panel?..someone had made a comment on not using a surge or gfi plug on a 3 wire...and I was wondering if there was any merit to the comment.

 

[LawnGuyLandSparky]

Re: sharing common for GFCI & other circuit

Curious if this GFCI issue is with a combination 120/240v GFCI / Thermostat / Floor heat sensor unit? From the look of them (I've been installing warm floors all winter) they're kinda flimsy.

Have you tried using an ohmmeter? You might actually have a ground-fault.