Why did the UK change from round pin to square pin plugs?

What! you believe that prat

Scott formulated the question :

No, there was a version of the plug which used round pins and the pins were actually the fuses.

The reverse; in the early days the lighting was the main load and the power companies wanted to increase daytime consumption to make it worthwhile keeping the generators running all day.

Owain

In the days of gas lighting, you did need to turn the supply off, to stop it leaking out when when the lights were off. So, it is understandable that some people brought up with gas lights thought the same applied to electric lights.

My mother fitted 15W lamps in her first home, as they were quite bright enough for somebody who had grown up using candles for light.

Perhaps she had 15A wire fitted to the fuse at the same time the socket was changed.

We are talking about different functions. I was referring to a 15 amp to 5 amp adapter at a time when small appliances had 5 amp plugs and large appliances had 15 amp plugs but you may need to plug the heater and the lamp into the same socket. .

I assume in photographic terms these would be two stops down from 60 watts.

My granny had a two pin socket on the floor rather than the skirting board. One day curiosity got the better of me and I was rewarded with

Yes, I thought Schuko was considered to provide better contact. The same cannot be said about Europlugs.

No, that would need 2 meters at that time.

The reason the light socket was used for stuff like ironing was because at that time there were very few normal sockets of any type in most rooms but there was almost always a light socket.

There were multiple reasons for the move to BS1363 square pin system. The old round pin system was recognised in the 40s to be thoroughly inconvenient, inadequate for increasing numbers of appliances, unsafe and frankly insane. It was a whole pile of unnecessary problems by design, plus there were lots of unsafe plugs, sockets, adaptors etc in use.

At the heart of the square pin system was the ring circuit. It enabled unlimited sockets to be fitted on just one ring of cable, on 1, 2 or 4 fuses. This was a huge money and material saving over a round pin radial setup with the same number of sockets, which mattered after the war. Also old 15A radials could be upgraded to add unlimited sockets relatively cheaply.

To put existing round pin plugs on such circuits is not safe. A lamp with a bellwire or speaker wire mains lead on a 2A plug & socket on a 32A fused ring is not ok. If the same sockets were used, this would be the inevitable common result. A different plug system was needed.

The new plug system was designed to be far safer than the crazy round pin system. It also had the desired effect of gradually taking all those round pin hazards out of service. If you've ever used round pin kit you'll know how bad it often was. Kicking plugs to get the pins to make contact was common practice for example. There were wooden plugs & adaptors, some with touchable live tubes. Irons & heaters on BC plugs were common etc.

IMHO it's time today to revisit the system to improve it a bit. 2 pin BS1363 variant moulded-only plugs could be added, enabling use of 3 appliances per single faceplate, 4 or 6 per double.

Yep.

Not very surprising that that applies to water taps and is applied to the new fangled electricity that most don't understand.

No, because: (a) that would probably not have space for the fuse, which is essential (b) that would not have the earth pin, which is required for opening the shutters and why even double-insulated power supply plugs have a plastic 'earth' pin (c) 2-pin plugs compatible with 3-pin sockets would not be polarised, which is required to ensure the switch and the central stud of ES lampholders are always in the live (d) you'd end up with 2-pin plugs that couldn't be used in 3-pin sockets and 3-pin plugs that couldn't be used in 2-pin sockets, and loads of adapters. Not having every socket having an earth would put us back to USA standards where they still have loads of old 2-prong outlets

Owain

Not compulsorily.

b) is not actually correct ... MK sockets don't use the Earth pin to open the shutters. They pivot the shutter at the centre and have a ramp on each side of the shutter so that the Live and Neutral pins press on the ramps and cause the shutter to rotate, with one side going upwards and the other going downwards in the vertical plane. They will work with wall-warts where the Earth pin has been broken off.

A BS3036 re-wireable fuse with 5A wire will supply a tad over 9A continuously. So fine with a 2kW kettle. (3kW ought to blow it in about

1.5mm^2 in clipped direct or embedded in masonry will take 20A continuously.

incorrect

some sockets use it for that, some don't. shutters opened by LN pins only have been with us for many decades.

correct. Figure of 8 leads are & many other loads are not polarised.

obviously mfrs would not fit them to ES luminaires.

some existing sockets would require a plastic pin to insert the 2pin plugs. The user has 3 options:

1. get a plastic pin
2. update your sockets
3. fit a 3 pin plug

No. The new socket layout has 5 or 7 holes rather than 3. It takes either 1x 3 pin or 2 or 3x 2pin plugs.

no need for any. The point is it would reduce adaptor use.

All sockets would still take 3 pin plugs without exception.

I don't disagree with what you say. I like the system.

However, if the argument was as persuasive as this, why did other countries (with minor exceptions) not follow and why is Schuko and its variants so widely used today?