Mains electrical safety - 1952 style!

[Boater Sam]

Yep, very typical. Fantastic place to be.

[Refugee]

I like the meter christmass tree.
I bet it looks good with all the blue flashes at night.

[philthespark]

A couple of points, firstly the "new" colour scheme for flexes that came in in the 70's, brown=live, blue=neutral, and green/yellow for earth, was indeed designed for colour blind people, the darkest colour went to live and the lightest to earth. Apparently no matter what colours are affected for different people, the brown is always the darkest and the green/yellow the lightest.
On the subject of the "unidentified" cores, some actually have a different colour interior, when we used twin red for switch drops in the early 80,s if you looked at the cable, both cores were the same shade of red, however if you looked at it end on, one was red and the other looked white, if you took a sharp blade and pared the insulation you could see the white inside. I seem to remember some twin flex years ago like that, one brown all the way through and one with a thin white centre.
I remember doing the old trick of stuffing the wires in the socket and jamming them in with another plug, as an electrician, it was almost expected of you to do it!, Where it got really tricky was on a metalclad socket, too much bare wire and it shorted out on the metal housing of the socket, insert wires under plug, force into socket, switch on, after loud bang and flash head to dis board and attempt to locate blown fuse. it never happened if the board was marked up, if it did go bang it was a dead cert you'd find the board unmarked.there was also the habit of wrapping a bit of silver paper around a fuse, a fellow spark I know actually had a piece of paper with the "current ratings" written on it, I believe he'd actually worked out how much current certain foils would carry. The foil out of an Embassy fag packet carried about 3 amps, a kitkat wrapper carried 5 amps, and I think the tinfoil his wife wrapped his butties in carried 13 amps.
It always makes me chuckle when I think back, being qualified electricians didn't mean we didn't bodge things up, we just did it to a safer standard. lol

[philthespark]

[QUOTE=Craig Sawyers;1008618]Sounds like the wiring nightmare in India, lots of which is illegal - people with not much money (and there are a very large number of them) just tap in a wire.

Some images of this madness here

https://www.theautomaticearth.com/20...hings-to-come/

I wonder what the DC offset of that lot is![/QUOTE

A mate of mine went to one of those dodgy countries, India or Thailand it was, he sent me a picture of a set of bare wires hanging out of a box right by the swimming pool! The following day he sent me another, he never goes anywhere without his voltstick, and yes those cables were live!
He said they had a raid by the power company and they ripped loads of illegally connected cables off the power pole outside his hotel window,though he said from the standard of work it was hard to tell what was legit and what wasn't. anyway late on that night he heard a noise and went onto his balcony, there was a bloke climbing up it with a length of cable wrapped around his arm,"it's ok mate, just putting my power back on" he said, and proceeded to attach said cable to wires on pole, when my mate awoke the following morning he said the pole resembled a spiders web! During the night, the locals had restored all the illegal tappings.

[emeritus]

The raised annular hand grip on the flex socket of the well-known Bulgin 3 pin 5A connector was designed so that it could be mated via a hole in the back of a set, meaning that the mains had to be disconnected before the back could be removed. This safety feature is explicitly mentioned in their 1936-7 catalogue.

[RojDW48]

Originally Posted by emeritus

The raised annular hand grip on the flex socket of the well-known Bulgin 3 pin 5A connector was designed so that it could be mated via a hole in the back of a set, meaning that the mains had to be disconnected before the back could be removed. This safety feature is explicitly mentioned in their 1936-7 catalogue.

Interesting that the old Bulgin plug has come up - many years back I worked in a very poor inner city school doing all sorts including theatre tech. Our only sound system was powered by a 50W Clarke and Smith valve amp from the 50s. An oily rag from the county 'provider' condemned it. 'Why?' I said, having recently checked it for electrical safety! 'It's dangerous' he replied. After quite a lot of interrogation he finally admitted it was the Bulgin plug (which could be unscrewed by hand) which was at fault......fair point - I had children trained up to do the sound. I phoned his boss (who was a perfectly sensible fellow) - and the young shaver, rather sheepishly - took it away, fitted an IEC chassis socket, provided a lead and it was still in use years later when I left.

[Boater Sam]

DIS BOARDS.
They look fine by 'pines standards, there are none at all here, they just connect everything together. With tape!

[G6Tanuki]

"Positive interlock" systems are quite common on mains-connectors: the original 2-pole rear-of-chassis power-connector on lots of 1940s-1960s Eddystone radios had the 2 insulated sockets on the cable protruding from the body of the connector, with a gap in between: sort-of like a fat two-pronged fork.

On the case rear-panel there was a metal pin which went across the centre of the gap between the the 2 socket-pins; When the plug was mated this pin passed between the two prongs of the socket and didn't impede full seating of the socket into the chassis. If you tried to remove the case with the power-connector still in, this pin blocked the case from coming off until you'd pulled the power-connector out.

[Tractorfan]

Hi,
The mention earlier of 'Fitall' plugs reminded me of this example out of my junk box. I assume it was meant for temporary use only. The blue ring was tightened upwards to secure the cores, and the white ring was tightened downwards to grip the sheath. The assembly was then pushed up into the body of the plug and the earth pin turned the correct way round to lock it in place. The label boasts that no screwdriver was needed to fit it.
Of course, it was dead easy to plug the 'empty' body in and poke a finger inside it.
I've also got their other one which would fit five different sockets. Did 'Fitall', based in Larne, Northern Ireland, make anything else?
Cheers, Pete.

[The Philpott]

Much of the theatrical lighting equipment at my school was elderly, with problems such as rheostats graded from 0 to 10 where 7 or 8 couldn't be used for long without overheating occurring. For some unknown reason students were authorised to work on the systems. They were quite capable of doing this (at least one of them was) but the cardinal mistake was made where they were both working on systems simultaneously in a situation where one should have been working and the other watching and holding a torch. The head beak was quite unpopular by the standards of the day (the eighties) and I remember wondering what he thought when he was told a student was in hospital with serious burns to his hands and a permanently non-functioning thumb. It grated on me that this was the same beak who had screeched at me on the one occasion that I was 4 minutes late for registration, and 'drinking....out of A CAN!!' I was left pondering the consequences of drinking Pepsi-Cola for several seconds.

Psychology wasn't on our syllabus, I learnt most of it by experience.

Second example in a factory in quite recent years- a 45 gallon drum of isocyanate sitting next to a smashed 13amp socket. Fire + Isocyanate = Cyanide. Nice.
In some unpleasant respects the 'fifties haven't left us.

[Refugee]

Cyanide was involved in an accident they had not long before a did a summer job at a metal plating outfit.
They had paid for a waste tanker to get rid of some frost damaged gold plating solution.
Once the waste was loaded they decided that there was enough room in the tanker for all the rest of the liquid scrap to their cost.
It burst the tanker lorry. Only the guy who walked with a limp was injured as all the others had run away while the lorry was swelling. The poor guy just could not run fast enough.

[Herald1360]

Not seen a DIN rail socket before!

[Refugee]

Originally Posted by Herald1360

Not seen a DIN rail socket before!

You just can't see the tape bomb that is holding it there. The adapter is blocking the view.

[GrimJosef]

Originally Posted by Craig Sawyers

... 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 ...

I did the same thing once (not with nail scissors) in a meeting room on the DESY Hamburg site. Given that the engineers in the meeting were responsible for a 1.25GeV superconducting linear electron accelerator powering an X-ray free-electron laser they seemed surprisingly twitchy about having 220VAC on bare-ish wires in the middle of the table. Given that 'needs must' they put up with it though, for which I was grateful.

Cheers,

GJ

At least it has circuit breakers! Makes my odd bit of "improvised" wiring positively safe.

[RojDW48]

The Philpott has reminded me of the theatre lighting we used in the same school (until I managed to get it changed to a 'modern' thyristor system). It consisted of 8 big full power rheostats. Lighting 'cues' were differing lengths of 2X1 to shove 2 or more wipers up and down as required. Needless to say our lighting cue sheets weren't terribly complicated!

But the classic was in the nearby Filwood Hall. I was asked to check to see what could be managed for a community production. The extensive lighting plan consisted of 4 enormous rheostats - the wipers were cast iron plugs which were raised by pulleys connected to winding wheels - they made their own way down by virtue of their great weight. 1935 they were installed - still working (for the brave at heart) in the 70s.

[Boater Sam]

Now this isn't a 1952 job but in a 20 year old building, my hotel room in Cebu.

I have no idea what the earth wire is connected to, its a 1st floor room and there are no earths on any wiring in here.
I like the red wire they used perhaps it signifies that the earth is live?

It works though, warm showers, lovely.

[turretslug]

Or done by an older German spark?

[Boater Sam]

Mmm, not a bright spark though. Air-con units are fun here, I never touch the metal case, just the plastic knobs or unplug them before switching on, they cannot be earthed!

[Boater Sam]

Some approved electrical distribution seen in our street in Cebu.
Its all official, HV, 5 or 10kV? 3 phase on top, transformers on pole, 240v phases below.
All the rest is a tangle of 'phone and data cables.
Some poles are vertical, others...........
The sparks walk on the data bundles to work on the 240v..........
During initial works here for a new hi rise block, a spark died whilst fitting insulation tubes on the HV where they were close to the crane and the new build. He was working live..............