Aged MK plug with switch

Dartlec · Mar 28, 2022

One for the more 'experienced' out there...

When was this available?

To 1363 apparently at the time, but without the sleeved pins..

Otherwise still working perfectly, so clearly a design that worked - and would be quite handy in some circumstances today.

I recall maybe 10 years ago a company did make a plug with a switch built into the front, but they soon disappeared, so perhaps they were considered unsafe in some way, or just not worth the cost involved?

In a house with a couple of the original MK sockets still in place, though the wiring seems newer than the 60s I'd guessed. When did these sockets go out and change to the newer style?

Fortunately the back boxes have the side lugs too, so changing them won't be a huge issue (The builders are going for a cheap refresh with not much plastering.

Bit of an odd house all round though, since it has floor ducted heating in the rooms, and a huge ceiling heating vent - all fed via a large heater in an outside cupboard......with solar water heating added sometime in the more recent past....

littlespark · Mar 28, 2022

Those old sockets have the extra screw fixing lugs on the back box top and bottom….
They might need knocked off to fit a new socket

Dartlec · Mar 28, 2022

littlespark said:
Those old sockets have the extra screw fixing lugs on the back box top and bottom….
They might need knocked off to fit a new socket

I'm hoping that the side lugs are the same dimensions as modern sockets though? Didn't actually try one and it would be a pain to replace back boxes since they were put in properly back then....

Julie. · Mar 28, 2022

Late '60s early '70's - mid '70s saw the more widespread used of switched socket outlets, so the switch on the plug wasn't needed anymore.

Most often would end up with contact weld, so just on!

Julie. · Mar 28, 2022

Dartlec said:
I'm hoping that the side lugs are the same dimensions as modern sockets though? Didn't actually try one and it would be a pain to replace back boxes since they were put in properly back then....

Could be ba screws rather than m3.5 metric, so keep the old screws safe to re-use.

Dartlec · Mar 28, 2022

Julie. said:
Late '60s early '70's - mid '70s saw the more widespread used of switched socket outlets, so the switch on the plug wasn't needed anymore.

Most often would end up with contact weld, so just on!

That would probably tie in - the house could well be early 70s,

This was doing a single light, so probably never had enough current flow to cause that...

It will go in my box of curios to show the young'uns when I'm old

pc1966 · Mar 28, 2022

Julie. said:
Could be ba screws rather than m3.5 metric, so keep the old screws safe to re-use.

I often suspected the use of M3.5 in the UK was largely due to the similar size to 4BA (~3.6mm) as you struggle to get them in the EU (M3 and M4 easy)

Julie. · Mar 28, 2022

pc1966 said:
I often suspected the use of M3.5 in the UK was largely due to the similar size to 4BA (~3.6mm) as you struggle to get them in the EU (M3 and M4 easy)

I guess so, the pitch is similar 0.66mm vs 0.6mm
And given there is only a few threads of depth in the "nut" part, the m3.5 screw will fit in a 4ba back box, but they are a bit loose and if the thread is a bit worn/slack, a bit too loose!

littlespark · Mar 28, 2022

Or use a M3.5 tap if you lose the 2BAs

I believe the distance between them are the same.

telectrix · Mar 29, 2022

and here'sme struggling to work out whymembers are referred to as@xxxxx.

pirate · Mar 29, 2022

I have a few of those old MK sockets in my house, built 1974. Only the doubles though. All the single sockets have been replaced. This suggests that the side lug spacing might be different but I haven't bothered to check...

littlespark · Mar 29, 2022

pirate said:
I have a few of those old MK sockets in my house, built 1974. Only the doubles though. All the single sockets have been replaced. This suggests that the side lug spacing might be different but I haven't bothered to check...

My childhood home was built around ‘74 as well. Same age as me. There was hardly a double socket in the place. Only a couple in kitchen… the rest were singles that have been replaced with doubles when I started work.

Wasn’t MK though, it was Ashley Rock, and they had metric M3.5 screws

7029 dave · Mar 29, 2022

Late 60's very early 70's I'm pretty sure those back boxes have fixed lugs on the side as well.
As mentioned keep the old screws to reuse as think its imperial.
Have not seen a plug in years like that still in use

marconi · Mar 29, 2022

Two quality MK products. The plug could handle 3kW and I bet the socket 3kW on each side. While a youngster growing up, my parents new house in 1965 had MK single unswitched sockets in each room - but only one per room! All the electrical equipment had to be located near it not that there was much with a plug on. Adapters were the order of the day. Anyway, the 3kW kettle was not automatic but my father cleverly used one of those MK switched plugs so it could be turned on and off. Over a many years of regular use the switch did not weld or stop functioning. White MK plugs were too expensive so we had 'charcoal' ones to avoid the blue flashes from arcing on the kettle and one bar electric fire. Never a brown scorch mark.

UNG · Mar 29, 2022

littlespark said:
Or use a M3.5 tap if you lose the 2BAs

I believe the distance between them are the same.

A M3.5 tap would not rethread a 2BA hole which is around 3/16" or 4mm
The socket screws were 4BA

UNG · Mar 29, 2022

If my auntie was still alive she probably could have dated it, she lived in Edmonton not far from the MK factory back in the 50's into the 60's, a lot of MK's products were assembled by homeworkers to earn a bit of extra money as a youngster I remember when we visited some evenings would be spent assembling plug tops. Can't remember what they were paid but ISTR they were paid by the hundred or the thousand plug tops assembled
I also remember them assembling Biros and other stuff as well it seemed to be popular at that time