UK When did back boxes "standardize"?

[lozarus]

Apologies if this is a bit of a boring one. It's purely "out of interest" as I have rather an obsession with old consumables etc (and I'm sure @Lucien Nunes will be along to tell me!)

The time finally came to replace 2x Britmac sockets. Not a problem - simply covered the existing backbox with a surface mounted metal clad double socket, used the original fixing screws for the Britmac faceplate to mount the metal clad surface box (by drilling 4 holes in corresponding places), brought the singles through a 20mm grommet and terminated to the new socket, with a flying earth lead to both the original backbox and new one (this was all singles in conduit, but the conduit wasn't acting as an earth - one had actually been pulled through)

But that's all besides the point. It just got me thinking when did the "standard" backboxes as we know them come along? I appreciate there's "lounge boxes", and previously top/bottom threads - but the general shape and size has always been the same (even when the threads were 4BA instead of M3.5). The original Britmac brand box in the photos is cast, and obviously has screws in the corners. It just got me thinking really as to when the standard started to exist. (I know the socket would have been installed 1963ish)

 

[Lucien Nunes]

Hmm, I'd have to look it up. The current standard is BS4662:2006 which superseded BS4662:1970. That I believe was when the metric version was introduced, but I can't remember the BS number of the imperial version that came before it.

 

[R-fur]

As per Lucien. when metric came they changed from 4BA screws to 3.5mm but the size was the same. Dont know when the standard size was introduced. I think MK was still producing boxes and sockets in the seventies that had four screws but were standard sizes.

 

[littlespark]

I couldn’t really answer the op question, but I’ve been working in an old ex council house, possibly early 60’s built??

3/4 conduit into metal boxes with 13A double sockets, but the boxes had plate screw lugs horizontally, as normal, and 2 top and bottom. The double sockets were fixed using these 4 holes.

Newer sockets just don’t fit, not shaped to accommodate these 4 extra lugs and you need to hammer them flat, and use the standard horizontal holes.

A number of single sockets in this particular house have had double pattresses fixed on top and the singles brought through. No earth wire brought through from the box though, so double sockets, no earth.

 

[ipf]

Early sixties probably late 13th edition, I would say.
I remember the 4 lug d sockets but you could also get the 2 lug ones...maybe it was a time of transition.
I don't think it was felt there was any need for back boxes in domestic prior to boxes being produced to present standard. Certainly not before current socket outlets came into being. The old round pin sockets always had plastic pattress/surface boxes and the round switches were general round bakelite mounted on timber bases, as were plenty sockets, with back entry cables through the timber. Photo from 14th edition guide book.

 

[pirate]

Here you go...

This in a flat built 1974. Incidentally, there are only 2 of these in the property, all the others, and there aren't many, are singles, MK, and of a more modern "squared-off" design. I wonder if the 4 screw ones were just old stock left in the van...