Grounding boxes

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Big D 40

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Maybe this is a stupid question, but it is one that has been on my mind for sometime. I don't know if any of the members here do older home rewires, but I do many of them. On occassion we will have to reuse an existing metal box that is plastered in the wall and can not be removed. We fish our romex right in the knock outs in the top but the boxes are not equiped for grounding pigtails. Is it illegal to remove the washer from the device in order to ground this box? I do not understand why the code allows the washer to be removed on surface mounted boxes in lieu of the pig tail. I know that clips can be used but to me they are not effective. Just wondering what you all think!:confused:
 
If flush mounted, it would probily be recessed enough to not let the device come in contact with the box except for the screws. No tight connection here.
 
When I face the old, black-metal boxes with brackets that were nailed to the stud and lath-and-plastered over, I usually use a carbide recip blade to cut the box loose from the plaster, and then a metal blade to cut the bracket.

If grounding is the only issue, I'd recommend using an unused cable-clamp screw sans the clamp (they're always a pain to get back in!) or drill and tap a hole as Frank suggested. Remove the box only if necessary; it's not easy.
 
Big D 40 said:
I don't know if any of the members here do older home rewires, but I do many of them. On occassion we will have to reuse an existing metal box that is plastered in the wall and can not be removed....
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I do my share of old house work, and if I'm rewiring to a plastered-in box, I replace the box. Those old, small black boxes they used around here 7 or 8 decades ago aren't good for much these days (as you've discovered...), and removing 'em makes the fishing much easier. I don't know how old your box is, but if it's really old the clamps might not be suitable for NM anyway.

With a little practice, patience, and a gentle hand you'll be able to get those boxes out without messing up the surrounding plaster.

Usually the box ears are screwed into the lath behind the plaster -- if you're careful you can score and chip away the plaster and get to the ears. Then score the plaster on the sides of the box, and use a fine-toothed keyhole saw to clear the sides of the box. (note -- this is precision work unless you have good plaster skills. Sawzalls and RotoZips need not apply :) No pressure on the pull stroke, gentle pressure on the forward stroke, you're trying to unbond the box from the plaster and slightly widen the hole without chipping the plaster or dislodging/rattling the lath...) Once you've done that, the box will come right out. Remove it, carefully trim the exposed lath where the ears were attached to fit a more generous old work box, and you're all set.

If it's one of the old nailed-in boxes, break out the sawzall and very carefully cut right alongside the box to get through box supports and/or nails. Score the plaster to the ouside of the cut first, and hopefully it won't chip beyond the cover plate's reach. You can use the sawzall because you'll be near a stud -- there's not as much worry about dislodging lath and vibrating it inside the wall as there is with the ear-secured boxes.

Good luck,
 
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It`s been many years since I dealt with plaster lath walls.It seems to me it would be easier in a situation like this where damage to the plaster is unaceptable to use crimp sleeves for space and a ground clip on the box.Since all grounds count as 1 wire you could easily leave a tail from the crimpsleeve and attach to the device and another short tail for the ground clip.
 
LarryFine said:
When I face the old, black-metal boxes with brackets that were nailed to the stud and lath-and-plastered over, I usually use a carbide recip blade to cut the box loose from the plaster, and then a metal blade to cut the bracket.

If grounding is the only issue, I'd recommend using an unused cable-clamp screw sans the clamp (they're always a pain to get back in!) or drill and tap a hole as Frank suggested. Remove the box only if necessary; it's not easy.
Click to expand...

That's what I do if I have a box with no cable entries on one end.
I remove the screw so that I can remove the clamp plate, and then I use a small piece of tape to fasten the screw onto the end of a screwdriver and re-install it. I sometimes use super glue to glue the screw onto the end of the screwdriver. It sure makes getting the screw re-started a lot easier.
I then use it as my bonding screw.
I've seen some boxes where the sparky used a clamp screw on openings that were in use (had cable in them). This is not good and not allowed.
If I'm removing a box, I'll cut around it with a keyhole saw and then push (or knock) the side that's not attached to the stud back into the wall void. Then I use a screwdriver to pry the box loose from the stud and push it into the wall, remove the nails with needlenose pliers, remove the wires from the box and then turn the box longways(?) and remove it. The plaster is hard on the saw, but this is the best way that I've found.
If the wood lath is close enough to the opening edge, I sometimes run screws straight in thru the box ears, thru the plaster and into the lath.
In the past, I'd cut the nail ears off a standard plastic box and attach it to the stud with drywall screws, but that's not allowed anymore (why?, I have no idea).
If the box is on a kitchen counter, or anywhere that will see a lot of use, and the hole won't require any repair, I will apply a bead of Silicone caulking around the box before I slide it into the wall and then wipe off the excess. It secures the box to the wall much stronger.
I do a lot of work on old homes, so I carry drywall joint compound and tape in the truck to repair the opening if needed.
Sorry for the long post on a simple subject, but one of the reasons I like this web site is because of the wealth of knowledge in how to do things in ways that save time or makes the job easier.
If this post helps anyone, it's worth the effort.
steve
 
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