Working in the shop yesterday, I work in production for concerts and events, we were building quad 120v/20amp power drops and stumbled upon something weird and new. We build them to be abused and super safe because musicians can be idiots. There is a new style raised face plate that fits on to the 1 and 1/2 inch depth metal box w/rounded corners and it has tabs that cover the receptacle holes
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Pic here
What possible reason is behind this? The tabs are threaded so they must have some purpose but we cannot figure out why or what. Removing them is a huge PITA and we can’t find the old style, we can tell it is a new method of manufacture.
Here are a couple of more pics so you can see what we are building
I’d have to have one in my hands to fiddle around with all my qustions, but are the broken-off tabs in any way meant to fit over the ground terminal hole, using the mounting screw of the socket? I’ve never seen a cover plate with holes where the socket screws go - that’s a very odd piece.
I just looked on Lowe’s site and found a whole set of matching ones with various combinations of plugs and switches, all of which have those tabs and the extra holes. Two have user questions about the purpose… and no answers. Huh. I’ll wait over in the corner for someone who has a clue to wander by…
Just a WAG, but I think they are somehow meant to serve in place of the nylock nuts you have used. Recepticals come with the screws that are intended to screw into standard boxes which have tapped ears to receive the screws, so to mount them on that faceplate you have to have some 6-32 nuts.
The odd shape might be so that they tilt and bind as the screw is tightened, providing a locking action without the expense of a nylon insert.
The tabs break out and are intended to be used as a back for the receptacle screws in the same manner you are using the nuts. Using nuts is a better way to do it. The shape has more to do with making them compatible for a few different device options.
An issue with your boxes as made the clamps aren’t to code, for movable boxes on SO cable you should be using strain reliefs like these ones. They work like a Chinese finger trap for wires so you can’t pull it out, it also helps prevent the wire kinking at the box and shorting.
We were puzzled by the lack of hardware but did not think this was relevant to tab mystery, the old ones came in plastic wrap these come loose. We noticed after your post that there was a tiny notation on the bar code sticker “with locking tabs”.
Built one out of used parts and some tabs we had “smartly” thrown away. Learned two things.
Don’t bend the tabs too much, makes it much harder to screw on
True but the Chinese finger cuffs don’t work for what I do, it is safe, this is how many others do it and the Fire Marshall doesn’t have a problem with it.
The finger cuff strain relief has never worked for me, everyone of our sub snakes that has one also has E-tape on the cable end to keep it from moving. On stage all it seems to do is cut people with stray wires. If there were some reasonably priced compression fittings that would do the job, I would be happy to use them. We have some nice ones on stringers (multiple quads on a single cable), every few shows there are wires exposed. Not safe.
I would be happy to be up to code, just give me affordable tools that work and I will. We aren’t cheap, spent about a $1000 for a dozen of those and six hours time with two guys, the Captain and the CIC, not lackeys.
Instead of the finger trap strain reliefs, what about theading the cable through a foot or so of of vinyl tubing or even Romex jacket that’s just large enough to fit the cable through?
Sorry this took so long, was away from a computer that will let me post links. FYI this set of receptacles are not to be used, they were built by an idiot. The tabs we salvaged were put in place of the nuts
The tabs are difficult to use and I will continue with the nylon washer nuts
I saw that picture before, but I still don’t understand. Are the tabs usually supposed to be bent 180 degrees to behind the cover? It doesn’t look like they would fit. You’d have to snap them off like you did, but that’s a lot of work, and leaves sharp edges. And what’s the use of all the metal not near the holes?
With the tabs in the original position, are those holes spaced the same as the holes in a light switch cover?
ETA: That link doesn’t seem to always work, but one of the other pictures at Capt Kirk’s most recent link.
It was a PITA to remove the tabs but we didn’t know what they used for at the time. There are score marks on the inside of the plate indicating where to remove them, we bent them up too much, will do it differently next time. We also made the last bend inward and checked for barbs. The receptacle hole has a more concave shape than the old style on one side of each opening.
