Time for re-design?

Not really.

There's no way of knowing how many and what capacity terminals would be needed in a back box.

Back box costs would increase - a lot.

There would be an extra connection point and potential cause of failure, similar to the US practice of pigtailing.

Would you extend 3 or 6 fly leads between a ring final socket and the back box with or without high integrity earthing?

If cables are neatly arranged in back boxes and not cut too short there is no problem with different terminal locations.

Owain

I cannot see that coming but there is potential for Wago type connectors on double sockets. I have seen a video of someone who mocked up one just as a demonstration. Light switches, single sockets and other 1-gang accessories could be problematic to fit in existing back boxes and that is where the real problem is in backward compatibility.

Richard

One common issue I do see is the copper wire deforming in a ductile manner under the screw, which is a form of stress relaxation

The wires are no longer under the same level of compression at the time of installation, so that would be one benefit of using wago style terminals in place of the screws.

Heck, the same idea could be applied to RCBOs/MCBs current carrying capacity permitted on the output terminals.

What I would very much like, though costs might put me off, is a system where what you can see - the plate, the socket holes, the switch - can be removed and replaced easily and safely.

I have seen so many cracked, broken and otherwise damaged faceplates over the years. As well as the ones that have paint slathered up the sides.

I think you could have a system where the cabling is terminated in the backbox, and the faceplate simply plugs into it. With some careful design, removing the socket wouldn't break the ring/radial connections and wouldn't expose live parts - a little like the base plates of cordless kettles. That could allow Joe Householder to change the colour of their sockets without disturbing the wiring, and would allow easy removal for painting etc. It would also be useful for 'smart' sockets (with USB ports etc) in that you could safely disconnect them when testing circuits, and it would make it easier to fit them in the first place.

You'd probably make this in three parts - the metal/plastic backbox that's part of the fabric of the building, the slim base contacts, and the socket faceplate. For better termination you might have three sets of Wago-style clamp, rather than having wires sharing screw terminals. Having separate base contacts would mean you could choose the size to fit the job - if you have 10mm2 cables for some reason you could get the right one to terminate those.

It might cost a bit more, but it pales into insignificance compared with electricians' time.

Theo

Sympathy? Perhaps. Willingness to invest? Not a chance - for the reasons Owain has given - plus the risk it'd end up requiring 40mm deep back boxes.

It may mean that back boxes have to be deeper. Cooker switches or light dimmers often have to be fitted to deep back boxes - and this is without them also being stuffed with extra connectors.

Wouldn't this be solved by having wago type screwless terminals on the switches and sockets rather than a modified back box?

Copper is pretty much creep-free. Unlike aluminium that requires a maintenance schedule.

The only cause of movement would be differential expansion between copper and the alternative material, normally brass.

While contact may be consistent I doubt it would enjoy the same pressure as a screw terminal.

Theo <theom+ snipped-for-privacy@chiark.greenend.org.uk> wrote in news:S5y* snipped-for-privacy@news.chiark.greenend.org.uk:

The "fly lead" moulded into the socket / switch would lead to a cost saving and could be more flexible than the heavier circuit cable.

Never had a problem with a decent size box and leaving adequate length tails. Some seem to think cable costs a fortune, so try and save every inch.

Since connections are always the weak point in any circuit, adding more than needed is nonsense.

When I checked the tightness of all the socket cable screws many years ago, and about 18 years after the house was built, many needed tightening. They weren't 'loose' but neither were they tight.

fine for hollow walls..but might make for deeper chasing in masonry

My mother's house was built in the 1960s and all the wiring in that property is stretched within a inch of its life - no slack anywhere. Remove a ceiling rose and you are in trouble as the wire tries to shrink back into the ceiling. Remove a wall socket and it will come forward just enough to get a screwdriver in to the terminals, and if replacing the socket one with a similar connection location has to be purchased.

Possibly means that you cant install back to back sockets in a stud wall.

Well many moons ago I bought some outdoor switches of French origin that did more or less this, but it was silly as in this case the depth of the box was far greater than ours!

Have you ever tried to cram a dimmer into a normal wall box without resorting to one of those spacer thingies? Nightmare. Brian

Some 'pro' electricians seem to take a pride in doing this.

A previous house, every cable was as short as possible. Almost impossible to replace a socket or switch if the positions were even slightly different. In fact, you could take the screws out and the socket or switch wouldn't move more than a fraction of a millimetre.

you're more likely to see sockets with wago type connectors on the back.