PVC extender and Metal box

[Rufer]

Hey there. I purchased some PVC extenders to make my outlets flush with my thick walls. After I brought them home, I read on the package it says "for use with non-metal electric boxes". Is there a danger in using the two together or is it something undangerous (perhaps a potential fitting issue?

Thanks a lot.

[knightfly]

There's a serious possibility that these will disrupt your ground if not wired with that in mind; typically a metal box makes the outlet body grounded by the fact that the receptacle is screwed directly to the metal box - this makes it so all metal parts are grounded to system ground.

With a plastic ring, it's possible to end up with only the frames of your receptacles grounded (romex ground)

I'm on the wrong computer to be able to search code to see if this is actually "verboten", but at the least I'd connect an auxiliary ground wire from your receptacle's ground screw to a metal screw inside the metal box, so that ALL metal parts that aren't either hot or neutral are at ground potential... Steve

[Rufer]

Thanks again for your time, Knightfly.