Mains electrical safety - 1952 style!

[AC/HL]

It's done live too, I expect the "electricians" learn quickly or not at all.

[Peter.N.]

Originally Posted by Herald1360

Not sure how a "Keynector" would help, here. You still have to connect that to the arbitrary customer's socket.
Now, what about the somewhat dubious "Fitall" plug?

The 'Keynector was for bench use, because although I had an array of different sockets I sometimes had to remove the plug from the set in the customers house to fit to the loan set.

I had one of these 'fit all' plugs on my Primax soldering iron, the type with sideways spring loaded pins.

Peter

[johntech]

I often think about electrical safety in the 50's and 60's I started work as an apprentice TV engineer in 1961 and on reflection thing where very different some examples below.
The backs of televisions and radios where often just held on by turn buckle type things.
So no security there. It was quite common for radios to have no fuses and this was when they could have been plugged into a 15amp socket!
On the work bench in the service dept we had no isolation transformers or trips.
We were quite proud of our "death leads" ie two crocodile clips wrapped with insulation tape to enable you to connect to the numerous different TV mains inputs in a trice !
And yet for all the increases in safety awareness one thing still confounds me. The BC lamp socket how has it been allowed that any child or adult for that matter can simply remove a light bulb and there is potentially 240volts with no protection whatsoever !
I wonder if there were more deaths from electrocution 50 years ago or were people more careful not to leave appliances on at night etc.

[Boater Sam]

Light bulb sockets have traditionally been dangerous. The BC is a lot safer than a reversed wired ES.
The are a few BC holders that only connect the pins when a bulb is in situ, OK for bulbs, no good for the smoothing iron! They are only low wattage surface contacts inside.

[barrymagrec]

Remember those BC inline adaptors with a two pin 5 amp socket sticking out the side? Many a 750 watt iron was plugged into those, taking things near the brink.

[Dave Moll]

Originally Posted by Boater Sam

Light bulb sockets have traditionally been dangerous. The BC is a lot safer than a reversed wired ES.
The are a few BC holders that only connect the pins when a bulb is in situ, OK for bulbs, no good for the smoothing iron! They are only low wattage surface contacts inside.

I also have somewhere an adaptor whose BC socket has a sprung shroud that ensures the contacts are recessed when no bulb (or BC plug) is present. I suppose it protects against accidentally brushing against the contacts, but it's still easy enough to push down with a finger and expose the contacts.

[stuarth]

"Death leads" were very useful in the workshop where the customer didn't supply the mains lead (presumably because all the cables were tucked away behind the furniture). We didn't have cables for all the wierd and wonderful connectors used by various manufacturers at the time.

There was even one maker of reel to reel tape recorders (Revox?) where the mains cable was attached to the case, and detached from the chassis when the two were separated, presumably as a "safety" feature! So out came the death lead again.

Stuart

[ColinTheAmpMan1]

Originally Posted by Richard_FM

One problem older PA equipment had was mains hum caused by an earth loop. Sometimes the earth was disconnected to stop this, leading to guitarists being electrocuted when their amps short circuited. making their guitars more electric than they should be.

While what you are saying here could certainly happen, I'm not sure that the deaths of various guitarists happened that way. I can see that an un-earthed microphone-and-stand assembly could become live and that a guitarist holding an earthed guitar in one hand and touching the microphone or stand with the other would get a shock across the chest, which would probably result in electrocution. However, a short-circuited amplifier would surely blow its fuse and therefore not become live?

My understanding of the situation revolves around the "death switch" on some American-produced amplifiers, particularly those made by Fender. This switch was marked "earth" and had two positions. The reason for its use was because the power-leads on amplifiers had only two conductors and therefore no proper earth, while the PA system would probably be earthed. The switch connected a small-value capacitor between either phase or neutral and the amplifier chassis. In one or other of the positions, the hum would be reduced. Can you see where this is going? If the least hum occurred when the capacitor was connecting the chassis to phase, any guitars plugged in could become live. This wouldn't be particularly dangerous if the guitarist holding the instrument kept well clear of any earthed items. However, if said guitarist reached out for an earthed microphone, or maybe another guitar where the amplifier it was plugged into had the "death switch" in the other position...Goodnight Vienna. Sometimes the capacitor might even go short-circuit, too.

There are tales, maybe apochryphal, about American-made amplifiers being shipped to Europe with the correct mains transformers for European supply fitted, but with the "death switch" capacitor only being capable of coping with 115V. It surprised some when the amplifier was plugged in to 240V mains and the capacitor exploded! Of course, this rather dramatically made the amplifier safer!

Colin.

[Richard_FM]

I've heard of one guitarist being shocked when he touched an earthed gas pipe at the back of a stage while playing a guitar that was unexpectedly live.

[dglcomp]

and any sound person asking if noise would go away by disconnecting the ground wire (a lot of them have probably tried it and found it worked) on any of the sound forums I frequent immediately gets shot down and told in no uncertain terms at the likelihood of death occurring if they were to attempt such a bodge.
This seems to be more prevalent in the US where earthed sockets are not necessarily present and adaptors to make earthed appliance fit into un-earthed sockets are unfortunately readily available )so called 'cheater plugs'.

[Ekcoman]

Blimey.... this brings back the days as a nipper of paper clip in the fuse box or was it silver cigarette paper inner packet? None fused round pin plugs as in our house and my mother plugging her iron to the light socket. My mum told me once that as no gas in the 1953 flood as local gas works flooded the visiting doc sterilised his blunt reusable hypodermic needle of the bar of the electric fire instead of using the gas hob flame.

[evingar]

Originally Posted by stuarth

"Death leads" were very useful in the workshop where the customer didn't supply the mains lead

Still are. Usually termed "Widow Makers" round this neck of the woods.

I repair various SMPSU's and occasionally you get modules in with daft multi-way sockets that facilitate both mains in and DC out. The mating parts of these these are almost always unobtainable or only available as a minimum order of daft quantities.

The way forward is a mains plug fitted with crock clips (the ones with insulted boots on, naturally - I don't want people to think I'm reckless )

My concession to safety is they are fed through a current limited bench supply, incorporating a variac and isolated.

The biggest risk with such things IMHO is to not put them away after use, especially if coupled with a disorderly workshop with a mass of leads strewn around over the bench.

[Boom]

Originally Posted by dglcomp

This seems to be more prevalent in the US where earthed sockets are not necessarily present and adaptors to make earthed appliance fit into un-earthed sockets are unfortunately readily available )so called 'cheater plugs'.

Of course 110V is a lot less dangerous than 240V.

[Bobdger]

My soldering iron had a pargo plug on it this was a 2 pin plug with very thin pins these were spring loaded and would fit any socket from a Wylex slot type to 30A MK power sockets. My death leads have a hole drilled in all of my 3Z plugs so when not in use a cable tye is feed through the plug stopping them being plugged in. I now also have a 3Z and N safe block made by cliff electronics and sold by RS. Much safer.
Bob.

[Oldcodger]

AH- the 50's, when my LA property was rewired. The first step was to knock a large hole into the old coal house, which had a warped door to the outside world. Next step was to create a hole in the plasterboard ceiling ( using screwdriver technology, I suspect, judging by the size and crude shape of the hole), leaving a fire-wind path to the upper floor.
Next came the earthing of light roses- earth were present, but not connected. Then the piece de resistance- the use of a door frame to allow a 13A ring main to descend from upstairs to down, with no protection. ( Discovered when a sofa caught the woodwork and wiring was seen). I did ask my elderly uncle ( time served sparky), what edition of regs outlawed this practice, and he struggled to remember. The door has been rehung on opposite side, as chippy refused to work on the frame on the side with cables.
Honestly, I'd expect to see the electrical certification signed by R Rogers, of Texas.

[kalee20]

I suspect that there was a fair bit of respect in the 1950's for mains power (plus there was just less equipment, so fewer opportunities for bad shocks).

Protection for the uninformed - such as very young children - has to be good these days, because there's just so much domestic equipment which is left permanently plugged in.

Originally Posted by stuarth

There was even one maker of reel to reel tape recorders (Revox?) where the mains cable was attached to the case, and detached from the chassis when the two were separated, presumably as a "safety" feature! So out came the death lead again.

The Thermionic Products 'Soundmirror' has the mains lead attached to the back - when removed, it takes the mains lead with it. So, for fault finding, you do need a Death Lead (or you just unscrew the mains connector from the back, whereupon it becomes just a mains lead ready to plug into the chassis power input).

[russell_w_b]

Here's mains electrical safety 1978 style; me as a 19yr-old yoof in the foundry electrical workshop at a part of British Steel, Workington... Granted, we were trained, as it were, being electricians, and there were rubber mats on the bench, but still...

415V live terminals covered by a paxolin box; 250V d.c. terms covered by a hardboard one - non interlocked. You weren't meant to work alone on the test bench, but everyone did. And we used those brown 13A plug adaptors for unterminated leads: the ones with three little colured buttons on that you pressed in to stick the bare ends into.

There were no fatalities or recordable accidents that I was aware of.

[Boater Sam]

Things have not got better in some places.
This is the power socket in our room at present, Filipino style 2018.

What is not immediately obvious is that this triple 2 pin extension socket is fed by a 1mm flat twin cable which runs up to the ceiling, and across to the centre light where it is wired into the lighting rose.
Oh, and just for fun, part way across the ceiling is a "Tape Bomb" onto a thinner bit of twin flex!

Now look again and you will see that the air-con unit has a 3 pin plug, into an adaptor to 2 pins inserted in the bottom socket. So no earth at all. But then there are no earths here anywhere, its single wire feed with neutral to earth "somewhere" at heaven knows what impedance.

Its feeding a phone charger, 2 computer chargers, a fan, and the air-con, doing well. All of the lighting circuit.

The TV, a 20" CRT jobbie, is plugged into a real double 2 pin socket under the bed, with 2 tape bombs in the lead, last bit of which is single insulated.

I've looked and found no fuse box yet...................

[sortedradio]

Hi Sam,
I guess this is the Philippines? I don't think they have any regulations here, but you have to admire their ingenuity! Here's a couple from one of my visits.

[Tractorfan]

Hi,
Just to add my two euros worth. These distribution boards were spotted in a Spanish supermarket not far from us. The second one is within easy reach of customers & staff, and the other one is hanging from the ceiling! As far as I know, they're still there.
Cheers, Pete.