Not always, IME.
Old British Standard back boxes incompatible with new electrical screws
- Thread starter phb10186
- Start date
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If that were the case, probably nothing that a file or drill could not cure.
You could try using this type of 2-part Epoxy Putty- https://www.amazon.co.uk/d/Epoxies/Cargo-QuikSteel-Steel-Reinforced-Putty-Metal-Repair/B005O0366Q
(Not cheap but can be used for other jobs.)
Kneeds like Plasticine. Sets hard within 15 minutes.
Fill the screw hole with a blob of this mixed resin, making sure that it is flat on the top but with a good few millimetres of the "blob" at the rear. Pierce through the hole before it sets (to save drilling.)
You can tap it after it has set, but you may even be able to use one of the new screws as a pseudo tap.
Taper the tip of a screw, wet it and, before the resin has fully set (within 5 minutes), use the screw like a tap to form a thread in the soft resin.
Carefully unscrew the wet screw and allow the resin to set - 20 to 30 minutes.
Keep a sample of the resin which you have used and test that it is hard before you attempt to apply tension.
Yes, that';s good stuff for this sort of job, but I don't know how well it would adhere to nylon (or whatever).
Kind Regards, John
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It is the metal wall box which requires a smaller threaded hole.
Oops!
Just noted that there are plastic inserts.
However, that should not matter if one uses a big enough "blob" to envelop/enclose the edges of the plastic since it will "lock on" when set.
Quite
The saving grace would probably be the existing thred in the plastic/nylon/whatever, which should hold the resin in. Were it not for that, and given that the 'blob' probably could not protrude appreciably out of the front of the lug, it might well be possible for it to be pushed out of the back of the lug.
Kind Regards, John
Your point is well made.Quite
The saving grace would probably be the existing thred in the plastic/nylon/whatever, which should hold the resin in. Were it not for that, and given that the 'blob' probably could not protrude appreciably out of the front of the lug, it might well be possible for it to be pushed out of the back of the lug.
Kind Regards, John
However, in my experience, this type of material is quite "tenacious" - in that it does tend to stick to just about everything - except "oily" plastics
As I mentioned, "if one uses a big enough "blob" to envelop/enclose the edges of the plastic it will "lock on" when set."
It really does "lock on" with but only a little overlap.
In addition to this, I have found that, if one "moulds" the resin concerned to a surface to which it then does not "stick" after it is set, the use of "super glue" between the new "moulded" part and the original surface is often enough for the two surfaces stick together.
Further, there are products such as what in Australia is known a "Bote Cote" (https://boatcraft.com.au/Shop/index.php?main_page=index&cPath=15)
While such products, designed for repairing wooden boats, may take over 12 hours to set, I find them invaluable for repairing many plastic and wooden items.
The addition of a "coating" of such a product is often all that is needed to effect a more permanent repair to an item which has been "repaired" with epoxy resin and/or super glue.
As you may glean from my response, I am more interested in repair than recycle, although I am more interested in recycle than dispose.
No-one can (or should!) argue with that.
One final point, for anyone who stumbles across this thread (which is almost a pun!). There's no problem in the OP's case, since he already has plastic/nylon inserts in the lugs on his metal back box. However, although many (like me!) prefer to have a bit of explicit wire doing the job, these days it is quite common to rely on faceplate screws to earth the backbox (the accessory having an earth connected). If that is the case, then, if the lugs are metal, putting any insulating material in (both of) the box's fixing lugs can disrsupt that connection (so an explicit wire connection would have to be added.
Returning to the question, I've seen it suggested that a coat of two of nail varnish on a loose faceplate screw may sometimes do the trick. If that does work then, again, it could (if done to both screws) disrupt the earth connection.
Kind Regards, John
The whole point of having nylon blocks for the threads, is that the lighting circuit does not have a CPC.
Nylon used to ensure the screws do not become live if the back box was to become live.
Unless it has had a rewire, in which case the backbox ideally should be been replaced, as the threads do wear out. QED
Nylon used to ensure the screws do not become live if the back box was to become live.
Unless it has had a rewire, in which case the backbox ideally should be been replaced, as the threads do wear out. QED
I know (at least that that is one reason for the non-conductive lugs) - that's why I said that the possible 'earthing issue' with using an epoxy filler (or nail varnish!) would only apply if the lugs were metal (for the benefit of anyone who might read the suggestion in the future) .
Replacing back boxes can be a hassle. If the lug can be made to work satisfactorily with a M3.5 screw, there's no harm in leaving it there (with its insulating lugs), with a earthing fly lead added if there is a metal switch.
Kind Regards, John
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