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

No, it was just that tehre were plentyof lighting sockets and few power outlets. When we moved into our fist house in 1964, it had 4 power outlets. One in each bedrooma and one in the kitchen, Neither livig room had one

No, but fixed heating was (at one time) cheaper.

You would struggle to fit a fuse in a 2A round pin plug.

I never had any trouble with round pin plugs and our mains power was DC until ~1950. I had all sorts of experiments connected to rotary transformers.

Does DC use the same fuses as AC?

This one?

I am sure this has to be right as otherwise two meters would be needed. However, I am sure I heard the story somewhere, maybe urban myth (along with the need to switch off sockets when not in use to stop the electricity leaking out through the holes and increasing the electricity bill).

As did my mother in the 50s. I reckon the irons in those days were barely 1kW. Add a 60 or 100W bulb, and you are still some way from the

I think my former neighbour had a 5 amp socket replaced by a 13 amp socket to allow her to plug in the kettle without changing the plug. My only consolation was that I assume the kettle was never left on when there was no-one in the house.

Oh, I never seen in the flesh one that old, the ones I recall were white cubic blocks,

Like this on , but adapting the other way round !

The ring main came about as the most economic way to use available materials in a time of shortages.

As an aside, I'm sure you're very pleased the latest jobs for the boys Boris scandal involves his mistress, not a boy?

I actually heard Alastair Campbell (Tony Blair's spin doctor) say on an interview programme, that he goes round his house doing just that, as his contribution to saving energy use.

I thought he was taking the piss, but I don't think he was.

It did in those days, when DC was always constant-voltage, as it usually is now. Some years ago, I ran up against an odd problem: a 25A fuse in a DC power line was blowing at 18A (measured with two AVOs in parallel). Not quickly, just drooping at power on and falling apart a few hours later.

Some of you will have guessed the answer: the fuse was in the switched path of a switching regulator, before smoothing. I estimated the duty cycle and calculated that the RMS value was about 35A. Problem solved.

Some DC is more equal than others...

I did find a bayonet adaptor while clearing out my late father's things (which he had probably cleared out from my grandmother's things !)

I've kept it, you never know, it might come in handy, though I'm not sure what our sons or grandson will make of it in 20 or 30 years time !

Wot - no 2 pin ones too? 15 and 5 amps came in 2 and three pin versions. But a two pin wouldn't fit a three pin socket. Or rather mostly.

When I re-wired my parents house, the round pin sockets were all in the skirting boards. Which were pretty small too. The new sockets all went in the walls at recommended height. Left the old (now disconnected) until they could be removed and holes filled in at re-decoration time. I changed the plugs on every appliance I could find to 13 amp. A couple of years later, got a call from my mother. Her sewing machine wouldn't work. I'd missed changing the plug on that and she'd plugged it into an old socket which hadn't been removed by then. And moaned about how inconvenient the only round pin socket she could still find was.

Round pins are better, if the socket is of the correct type. Even sprung flat contacts against flat pins only make contact at a few points. Neither surface is completely flat, nor are they guaranteed to be parallel.

One type of low-resistance socket uses round pins and multiple spring wires in the mating socket, tilted sideways at a small angle, so they are tangent to the pin. So the pin potentially makes contact at as many points as there are wires.

Not entirely practical for the domestic market.

D&S. Dangerous things. Had a habit of pulling them out leaving the fuse sticking out of the live. And a natural reaction is to pull it out with your fingers...

In those days. the two common cable sizes use for sockets were 3/029 and

I do recall 2 pin sockets. Same as shaver plugs. In fact for some reason I recall our Pifco Christmas Tree lights, a bit like these...