A Thread About Boring Old Plugs And Fuses

OnlQQker · Mar 7, 2020

Nothing much has changed with them since the beginning. Perhaps now a lot of things come with moulded plugs and you don't need a screwdriver to change the fuse except perhaps for popping it out. And for people with no knowledge whatsoever can put a 5amp fuse into the washing machine and I guess at the worst it will blow . But what of the people putting a 13 amp fuse into a table lamp.
It all seems very 1940's still though...

I'm trying to find out how small an mcb could actually be? Could it fit where the fuse goes at the moment in a plug if it was taken away. This way nobody would be able to install the wrong fuse.

I've just put a new plug on my extension lead and started thinking about it. Just found this interesting video about what is actually inside an mcb, this chap has a lot of very well explained video's for anybody else interested in stuff.

View: https://youtu.be/u6I7dKDk7hE

static zap · Mar 7, 2020

KISS .
An Engineering idiom.
Simplest solution is probably best.
Fewer connection points .
=Low costing -very important with -Suppliers having to provide
solutions to customers from many countries==
( We are already a bit special with the need of an earth pin !)
Just think how many G's a plug does when its dropped on to concrete.
(Calibration of anything more fancy is likely to change when abused/ un-obvious bypass =Make do strategy )
They do get crushed / trodden on !

OnlQQker · Mar 7, 2020

static zap said:
KISS .
An Engineering idiom.
Simplest solution is probably best.
Fewer connection points .
=Low costing -very important with -Suppliers having to provide
solutions to customers from many countries==
( We are already a bit special with the need of an earth pin !)
Just think how many G's a plug does when its dropped on to concrete.
(Calibration of anything more fancy is likely to change when abused/ un-obvious bypass =Make do strategy )
They do get crushed / trodden on !

That's a good point, thanks for posting.
I used to do a lot of jobs for a famous actor and ended up becoming good friends. His house in Mursley had been wired before I had met him. Anyway every socket, every light was on it's own mcb. He had 4 maximum way cu's. I couldn't believe it when I saw it. His argument was that nothing was ever fused wrongly (table lamps on 6amp, individual sockets on 16amp) and only the one thing would ever trip if a bulb blew for example. This was a big house so you can imagine the bundles of wire coming out from the back of the cu's

I guess I was thinking back and trying to simplify his fuse problem if nothing else! Anyway I'm off to cut the grass now as it seems not far off being knee deep which is rather odd for this time of year.

Thanks again for your reply...

Lucien Nunes · Mar 7, 2020

The only reason we have fused plugs in the UK and UK-derived systems is that while trying to streamline our unruly assortment of different types of plug ready for the housing revamp at the end of WW2, we came up with the idea of saving cable and improving load diversity by using circuits of much higher rating than the sockets and appliances themselves, i.e. 13A sockets on 32A circuits. Much of the world uses circuits of the same rating as the sockets and therefore does not need fused plugs.

what of the people putting a 13 amp fuse into a table lamp

That's generally fine now. For many years, appliances sold in the EU are suitable to be protected at 16A since that is the highest rating of domestic socket-outlet circuit used with unfused plugs. In the UK, we dropped our old 0.5mm² table lamp flexes (which required a 3A fuse) in favour of 0.75mm² which is OK for short-circuit protection at 16A and is protected against overload by the nature of the load.

In 1986, the IEC proposed an international standard 16A plug (IEC 60906-1) which incorporated the best features of European systems, although it wasn't revolutionary enough to be worth whole countries re-equipping to use it, and was only significantly taken up in Brazil and South Africa. Because of the difficulty of adopting an unfused 16A plug in the UK without rewiring our existing 32A circuits, I pushed the idea further to incorporate UK-compatible features including an MCB in place of the switch in each socket-outlet. The thermal trip rating of the MCB adjusted itself according to the type of plug inserted (e.g. 60906 or Europlug) which also provided an interlock so that the MCB would trip unless the plug was fully inserted. My scheme extended to 3-phase versions that would accept single-phase plugs, etc. and I even did a 3-minute spot on TV explaining it. Then, my girlfriend decided I was spending too much time playing with plugs and switchgear etc and the project was abandoned.

OnlQQker · Mar 7, 2020

Lucien Nunes said:
The only reason we have fused plugs in the UK and UK-derived systems is that while trying to streamline our unruly assortment of different types of plug ready for the housing revamp at the end of WW2, we came up with the idea of saving cable and improving load diversity by using circuits of much higher rating than the sockets and appliances themselves, i.e. 13A sockets on 32A circuits. Much of the world uses circuits of the same rating as the sockets and therefore does not need fused plugs.

That's generally fine now. For many years, appliances sold in the EU are suitable to be protected at 16A since that is the highest rating of domestic socket-outlet circuit used with unfused plugs. In the UK, we dropped our old 0.5mm² table lamp flexes (which required a 3A fuse) in favour of 0.75mm² which is OK for short-circuit protection at 16A and is protected against overload by the nature of the load.

In 1986, the IEC proposed an international standard 16A plug (IEC 60906-1) which incorporated the best features of European systems, although it wasn't revolutionary enough to be worth whole countries re-equipping to use it, and was only significantly taken up in Brazil and South Africa. Because of the difficulty of adopting an unfused 16A plug in the UK without rewiring our existing 32A circuits, I pushed the idea further to incorporate UK-compatible features including an MCB in place of the switch in each socket-outlet. The thermal trip rating of the MCB adjusted itself according to the type of plug inserted (e.g. 60906 or Europlug) which also provided an interlock so that the MCB would trip unless the plug was fully inserted. My scheme extended to 3-phase versions that would accept single-phase plugs, etc. and I even did a 3-minute spot on TV explaining it. Then, my girlfriend decided I was spending too much time playing with plugs and switchgear etc and the project was abandoned.

That's an interesting read, thanks for taking the time to write it. I'm guessing your girlfriend didn't like you playing around with other sockets

Shame though, sounds like you was on to something!