Mains electrical safety - 1952 style!

[Boater Sam]

Terrys' think of everything.

[Dave Moll]

Originally Posted by turretslug

The dopey librarian tale is all too redolent of my and no doubt many others' schooldays- "Know your place and don't dare question your elders and betters- even when they're conspicuously wrong!" Yuk.

Nowadays, it's generally considered that the average 13-year-old almost intuitively knows far more about modern technology than the adults.

[Station X]

Only about how to use it, not how it works.

[AJSmith625]

Does anyone remember the mini immersion heater advertised in the Sunday papers back in the 70s, designed to heat a cup of water. This also had this type of flat unmarked mains lead. I seem to remember it being brought to light on Esther Rantzens Thats Life programme.

Alan.

[PaulR]

Originally Posted by Dave Moll

Nowadays, it's generally considered that the average 13-year-old almost intuitively knows far more about modern technology than the adults.

Our school had round pin plugs (BS 546?) but the headmaster clearly had something different as he once brought his slide projector in as a treat for assembly, took the plug off and pushed the bare wires into the socket and held them in with match sticks. The lights were them put out and he did a slide show to an assembly of 5 - 11 year olds. Even though only aged 7 at the time I remember thinking how dangerous that was. I dare say that if anyone had touched it and survived a few strokes of his cane would have been administered for being so stupid!

[dseymo1]

I used to have a rather stylish table lamp fitted with similar cable, but in white with a green centre core - perhaps a little more obvious than the monochrome variant.

[Herald1360]

Originally Posted by MrBungle

I would say that I am a fan of fitted plugs but it appears that some of them are just as terrible as them not being fitted. In the last few years I've seen ones with so little plastic that you can't get hold of them, clearly because it saves a few pence. Then there are the ones with a partially plastic earth pin (why?!?!?). And on top of that I've had a couple where a pin has been left in the socket.

Ergo I'd rather snip them off and stick a nice quality MK urea formaldehyde plug on. Problem is, those are rather expensive.

The expense can be reduced by only using MKs or similar for equipment using a bit of power- say more than about 500W. I don't worry about (properly wired) cheap 13A plugs on 2A or less devices unless they're really tacky.

[PaulR]

Having seen the post above I thought I would look to see how much MK plugs are these days. Almost the first thing I came across were silver plated audio grade Hi-Fi 13A plugs!! Now they will make your audio system safer and sound so much better.

[Refugee]

Be careful that they are not plated all over and right up to the pins.
The plating could short out on the live side of the fuse producing a substantial audio output.

[turretslug]

It's the question of scale thing again- striving for quality in a system is a good thing, but awareness of perspective and knowing where to stop is also a good thing, otherwise perfectionism, vanishing returns and madness all beckon. A fundamental part of good engineering is awareness of scale and significance.

There's obviously loadsamoney to be made out of perfectionism, though....

[carnivalpete]

Re: Mains Electrical Safety-1952 style
In about 1952 when I was 8yrs old, I and the family were sitting in the back room listening to a radio prog on a large floor-standing radio when we heard a loud buzzing noise coming through the speaker.

My older brother, an RAF trained radio and radar technician, knew something was afoot with the power supply but could see nothing obviously wrong and so went to have a look around the house.

On entering the front room he found my sister, aged 6, sitting on the floor wearing a pair of my crystal set headphones. She had pushed the two wander plugs into the un-shuttered, 2-pin, round-pin, socket on the skirting board. She survived unharmed, but I'll never be sure how.

Our home at that time was a 1938 semi, under-provided with only a tiny number of 2 or 3 pin, round-pin, 5A or 15A, un-shuttered sockets downstairs, plus a cooker control unit with an integral 3 pin socket for the kettle in the kitchen.

In the backroom the ceiling fitting had a single bayonet light socket with a two-way switched adapter in it, with one branch holding a light bulb and the other branch free. When mother need to do the ironing, the electric iron, fitted with a bayonet plug, was connected into the free lighting socket. I was too young to know that I should have been suspicious about the gauge of wire in use in the rewirable-fuse box.

Incidentally, my RAF brother would never have committed the common sin of holding bare wires in a socket with match sticks. Absolutely dreadful technique. No, he would always strip about an inch of wire and fold it back on itself before shoving that into the socket and it always seemed to work very well.
pete

[Breton56]

When I was a young lad many years ago, I needed to change a plug on one of dad's extension leads. Taking the top off the plug I found it to be wired in a random order, say green to phase black to earth and red to neutral. Asked dad about his colour code and the answer was to the effect that he had wired the other end to the same code so what's the problem?

Electric irons fed from light sockets were very common when I worked at one of the local radio and TV shops but at least the boss would not supply to anyone who wantwd to use an iron in that way.

[McMurdo]

Is there nothing at all to differentiate the cores in that brown zip wire? When I was a lad mum went to the lighting shop to get extended flexes for the bedside table lamps, and was given the ubiquitous white zip wire. Obviously table lamps are single pole switched and should always be switched live for safety, and the guy in the shop showed her how one core had a little ridge in it. Since then I've also seen mains zip wire with one plain copper and one tinned copper core, or with cores of round and square cross-section insulation which is easy to spot when viewed end-on.

Our old TV repair man used to service our G8 by unplugging the 13a plug, sticking the bare wires of his soldering iron in the socket and plugging the TV in over the top of them, and relying on the tv mains switch for isolation while working on it.

But that was safety, 70's style!

ps: The same TV guy used to run 'Barex' crt rebuilders, if anyone comes across a label on a tube

[Peter.N.]

I'm sure there must be other engineers like me that are red-green blind, in the '50s I had the embarrassing experience of having to ask someone which wire was red every time I had to change a complete mains lead, was I pleased when they changed the colours.

Kevin

Sticking the wires in under the plug was standard practise in the '50s and much later for some of us I was tickled pink when the 'Keynectors' came out that you could stick you wires into without having a plug on top.

Now everything has 13 amp plugs it's not a problem but there were about half a dozen different fittings until then.

Peter

[RojDW48]

Sticking the wires in under the plug was standard practice in the '50s and much later for some of us

Yes, I've done it ...and worse.

There is method behind the madness of using lighting sockets for irons and the like (record players, electric fires... anything really!). Back in the 50s/60s Landlords renting bed-sits were required not to charge for lighting, at least in Bristol that was the case. It was an early example of Health and Safety regulation - presumably so that the tenants could find their way out when the 15amp circuit gave up the ghost and caught fire. All in all it was, at best, counter-productive!

[Dave Moll]

Originally Posted by Peter.N.

I'm sure there must be other engineers like me that are red-green blind, in the '50s I had the embarrassing experience of having to ask someone which wire was red every time I had to change a complete mains lead, was I pleased when they changed the colours.

I seem to recall that this was the very reason for adopting striped insulation for the earth wire - so that it was the one that really stood out, even to someone totally colour-blind.

[Craig Sawyers]

Originally Posted by PaulR

Our school had round pin plugs (BS 546?) but the headmaster clearly had something different as he once brought his slide projector in as a treat for assembly, took the plug off and pushed the bare wires into the socket and held them in with match sticks. The lights were them put out and he did a slide show to an assembly of 5 - 11 year olds. Even though only aged 7 at the time I remember thinking how dangerous that was. I dare say that if anyone had touched it and survived a few strokes of his cane would have been administered for being so stupid!

This thread reminds me of three things. First was my father in law, at this stage to be. He was a fire officer, and at this point in the early 70's in specific charge of fire prevention. But he had wired the domestic iron, done a poor job of it and then re-insulated the mess with insulating tape. I was, aged 18, horrified. I pointed it out to my wife to be, and then sneakily rewired it properly. I received no thanks (said father in law never approved of me - probably thought I was an uppity young oik. In fairness that was not far off the truth!)

The second thing was much later, when I was in Sweden on business. I needed badly to do some work in my hotel on the laptop, but had forgotten my mains adaptor. So using my nail scissors (which I had ground the ends rounded so I could get them through airport security) to chop the moulded UK mains plug off, strip the ends, and poke them into the Schuko socket. Wired on a mains plug when I got back.

Finally, another hotel story. This time in a small hotel in Cardiff maybe ten years ago. The room next door to me had a faulty time switch on the bathroom fan, it had run 24/7 probably for years, and hence had totally knackered bearings and made a fearful racket that was keeping me awake. I eventually reasoned that our rooms were probably on the same breaker. So I took a light bulb out, wrapped a spoon (from the courtesy tea tray) in a towel and shoved it in the light socket. Short flash and then - glorious silence!

Dear readers, don't try any of this hotel tomfoolery. Decidedly not advised!

[Richard_FM]

My grandparents were having some home improvements in the 1960s, & the builders managed to leave a flex connected to the mains with an empty light socket at the other end.

somehow one of my aunts (then 4 years old) managed to find this & give it a lick like you would do with a 9V battery...lucky for her she was wearing rubber soles....

[julie_m]

Your whole body is capacitively coupled to Earth, not just the soles of your feet. And anyway, there was a good return path through the other contact in the lampholder .....

[kirstyd]

i may have mentioned this before here but it still makes the hair on my neck stand up when i think of it even though it happened some 35 years ago .I went into the kitchen one morning to find my three or four year old daughter with the plug that went into the kettle in her mouth the other end being plugged in and switched on