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Grounding requirements-- condo conversion


Brandon Whitmore
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I just finished inspecting a whoppin' 350 sq. ft. condo. The structure was originally an apartment complex built in the 1920's, and the conversion was just completed.

The panel (non- service equipment) is located inside the condo unit. All of the wiring entering the panel is new Romex. The majority of the wires are new Romex as visible at boxes (I pulled all receptacle/ switch cover plates, and capped junction boxes). 1 switch and one receptacle (directly below this switch) had old cloth covered wiring--- 2 wires with no visible grounding wire. The junction boxes were original (metal). These junction boxes were inset to the inside surface of the wall finish (maybe 1/8" inset from the backside of the wall finish). The receptacle and switch were attached to the boxes via screws, but yolks were not contacting the metal boxes, seeing as how the boxes were inset.

Questions:

1)How inset can the boxes be by current code? (haven't looked it up yet).

2)If these boxes are inset too deeply per current code, would the new electrical code be applicable since all new switches/receptacles were installed throughout the unit-- meaning that box extenders should have been used?

3)My 3 light tester showed a proper ground (still haven't picked up a better tester), but are screws sufficient when the yolks are not in contact with the box? Also, shouldn't a supplemental grounding wire run from the receptacle/ switch to the metal box anyways?

4)I can't verify a proper ground connection visually. I will assume that BX wire was originally used, and that's what is in the wall between this switch and receptacle. Since the BX no longer runs to the panel, would the BX be allowed as a ground if a new grounding wire connects to a metal box attached to that BX?

PS: the switch/ receptacle are about 10' from the panel.

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I just finished inspecting a whoppin' 350 sq. ft. condo. The structure was originally an apartment complex built in the 1920's, and the conversion was just completed.

The panel (non- service equipment) is located inside the condo unit. All of the wiring entering the panel is new Romex. The majority of the wires are new Romex as visible at boxes (I pulled all receptacle/ switch cover plates, and capped junction boxes). 1 switch and one receptacle (directly below this switch) had old cloth covered wiring--- 2 wires with no visible grounding wire. The junction boxes were original (metal). These junction boxes were inset to the inside surface of the wall finish (maybe 1/8" inset from the backside of the wall finish). The receptacle and switch were attached to the boxes via screws, but yolks were not contacting the metal boxes, seeing as how the boxes were inset.

Questions:

1)How inset can the boxes be by current code? (haven't looked it up yet).

If it's a non-combustible wall covering, such as GWB, the front edge of the box can be set back from the finished surface up to 1/4". If it's a combustible wall covering, such as wood, the front edge of the box or extension ring has to be flush with or proud of the finished surface of the wall covering. 314.20

2)If these boxes are inset too deeply per current code, would the new electrical code be applicable since all new switches/receptacles were installed throughout the unit-- meaning that box extenders should have been used?

I would hope so. But if it's only 1/8", that's within acceptable limits for drywall anyway.

3)My 3 light tester showed a proper ground (still haven't picked up a better tester), but are screws sufficient when the yolks are not in contact with the box? Also, shouldn't a supplemental grounding wire run from the receptacle/ switch to the metal box anyways?

On a normal receptacle, the screws alone aren't sufficient to ground the box (or the other way around for that matter). You're supposed to run a short jumper to the box. There's a little green clip that you can use to fasten the grounding wire to the box.

The do make self-grounding receptacles in which the screws can be used as part of the grounding path. You can tell these receptacles (and switches) by the little brass plate/clip that's tucked under the screw head.

4)I can't verify a proper ground connection visually. I will assume that BX wire was originally used, and that's what is in the wall between this switch and receptacle. Since the BX no longer runs to the panel, would the BX be allowed as a ground if a new grounding wire connects to a metal box attached to that BX?

Yes. The BX sheath can be used as a grounding conductor.

PS: the switch/ receptacle are about 10' from the panel.

It shouldn't matter.

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Thank you sir,

You're just the man I was hoping for a reply from.

Quote: PS: the switch/ receptacle are about 10' from the panel.

It shouldn't matter.

That was to let everyone know that a false ground on one of the fancy receptacle testing devices may not have worked to check for a false ground.

Quote: 2)If these boxes are inset too deeply per current code, would the new electrical code be applicable since all new switches/receptacles were installed throughout the unit-- meaning that box extenders should have been used?

I would hope so. But if it's only 1/8", that's within acceptable limits for drywall anyway.

It was 1/8" inset from the interior unfinished side (wall void side vs. visible side) of the wall finish, meaning the rough wall framing was exposed----- I'll just write it up.

In my report I recommended a box extender to take care of the inset box. I also mentioned that I couldn't see a visible ground, and recommended GFCI protection just to be safe.

Thanks again.

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Quote: PS: the switch/ receptacle are about 10' from the panel.

It shouldn't matter.

That was to let everyone know that a false ground on one of the fancy receptacle testing devices may not have worked to check for a false ground.
Well, we folks with those fancy devices don't need to be told that; it's clearly explained to us in the users manuals and when we encounter that we use alternate methods to confirm the reading.

ONE TEAM - ONE FIGHT!!!

Mike

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2008 NEC 314.5 no more than 1/4" seback from the finished surface unless the finished surface is of combustible material then it must be flush.

200? NEC 370-21 No greated than 1/8" gaps to sides of boxes.

200? NEC 370.20 Clearances at mudring matches 314.5 standard above.

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