314.40d

[spectra05]

if i got a metal WP box already mounted with PVC/ENT And the factory grounding points wont lock down with a ground wire wrapped around it (but it locks without a ground wire on it) can i drill and tap a new hole for the ground screw? though if i do that the ground screw will go into the wood because of where the box is at. And/or can i use one of those u shaped connecters(not sure the name of them)(kinda like what they use in cars) and if i can must it be specifically for grounding? im trying not to have to pull the box apart because every thing else in the box is wired with conductors running through it.

 

[wireman71]

WP box grounds are poor for the most part. Have no idea how UL ever passed them $$$. In this case much as I don't like rigging things I'd just LR the ground to the back of the box and into the wood.

 

[spectra05]

sorry, wireman but what does LR the ground mean?

 

[mistermudd]

Square drive. It would be okay to tap & use a machine screw (more threads per inch to grab metal).

 

[benaround]

Yuo can also use a self-tapping machine screw.

 

[don_resqcapt19]

Try a longer screw of the same thead type as the original. It sounds like the screw is too short to bite when you put the groundind conductor under it. This is not uncommon with the factory supplied thead forming screws.

 

[guschash]

Drill & tap would be fiine.