Grounding question

[chrisf8657]

I have an existing grounded 4x2 box that I want to add an additional box above. The boxes will be connected together using a spacer/coupler.

My questions is does the second box need to be grounded also per NEC, or does the steel spacer/coupler basically join the two boxes together so only one needs a ground?

Thanks guys!

 

[hj]

I owuld say no, because the boxes are painted and the "coupler" will probably NOT make a good contact with the metal.

 

[Sponsor]

 

[WorthFlorida]

At one time with metal conduits and boxes the pipe and boxes were used as a ground as long it was grounded at a location. This was very preventlent when three prong receptacles were required by code. Over the years it was not alway reliable especially when PVC conduit came available and it would get mixed with the metal.

 

[chrisf8657]

Well, I'll clear up those two things: The spacer/coupler is metal, and the boxes are not painted, they are bare steel (non-wet location).

 

[Stuff]

As long as the spacer/coupler is UL listed it would be considered metallic raceway/conduit that is an acceptable grounding method. Lots of opinions out there that don't like it so run a ground wire anyway.

Note they are still two separate boxes so in each box all grounding conductors need tied together and connected to the box.

 

[Reach4]

My questions is does the second box need to be grounded also per NEC, or does the steel spacer/coupler basically join the two boxes together so only one needs a ground?

That device is often called a box-to-box connector or box spacer, but can be called by other names.

 

[chrisf8657]

OK - thanks Terry and everyone, I'll play it safe and ground both.