Live Chassis Safety

[Herald1360]

Originally Posted by David Simpson

.........

I say bollox to anyone who insists that an AC/DC set, or winky-wanky un-earthed set, or whatever, must remain in the un-safe state it was sold in all those years ago.

Regards, David

Not un-safe, just less idiot proof than a new one would be.

Good luck with arguing your case in court if anyone were killed by a set you'd modified for extra safety!

[Kyle__B]

Originally Posted by JohnBG8JMB

"No vintage radio these days should be powered up from the mains without a correctly fused modern 3 pin plug, using modern 3 core flex, & definitely not with a suspect possibility of a live chassis"

It's all very well to pontificate but some of us live in the real world and not necessarily in the UK, If the UK 3 pin and ring mains are so good, how come the world does not use them? How come the IET keep upgrading THE WIRING REGS? If you look deep enough into the origins , you'll find saving copper at the bottom. 13 A plug is a monstrous thing physically and can be and is frequently incorrectly fused... I think not fit for purpose today; compare the size of 13A 6way dis board with a EU 2pin one, or even a EU 3 pin one. When I explained the system to a French sparky his comment translated to 'what were they on?'. If you want a hazard, consider a light socket - or PME.

It's sad how many have jumped on their h&s [ticklist?] bandwagons and ignored the original question.

rant over!

Take care all.

John

If you go to Europe you can find towns and villages where one end is in one country and the other end is in a different one. The nearest shop to buy a telly or radio is often across the border, or if not you might cross one twice a day just for work. So they all use similar enough systems because it's trivial to do and they need to be compatible to each other.

Meanwhile the UK is an island. You can't accidentally cross over into France to buy a new Blogginex, and it was quicker to make our own standards than it was to import them.

Being born in the UK, living my whole life there and then moving to the Netherlands in recent years, I have to say there's more than a few problems with your idea of the facts.

It's difficult to see how a UK 3 Pin plug is "physically monstrous" or "not fit for purpose" compared to a European equivalent. Let's look at Europe:

- A schuko is exactly the same size as a UK plug.

- Nothing is polarized, even in it's variants which only plug in one way around.

- When they revised it to allow for an earth at all, they did it in such a way that old unearthed plugs don't fit earthed sockets, but earthed plugs fit unearthed sockets.

- New two pin plugs continue to be sold, in three different shapes. One for old sockets, a slimline "europlug", and a modern plug with the earth connectors simply missing.

- old type unearthed sockets still made and fitted, even in new houses! In countries like the Netherlands they are standard in every room except the kitchen, rendering earth protection defacto nonexistent. (!!!!)

- Both plug and socket are easily damaged in normal use. Sockets are composed of many small parts which are fiddly to wire and prone to bending and binding up. Common to have several sockets in a house which can only be plugged into with assistance from a hammer (!!!!!!)

- Lights on same radial as sockets.

To sum up, you can either have something that doesn't need an earth but can't be plugged in, or you can have something that does need an earth but can plug in where it won't get one, what's Line and what's Neutral is at random, there's a fair chance it'll get damaged just plugging it in, and if you trip the breakers you have to go looking for the fusebox in the dark.

I suppose though you can't accidentally put too big of a fuse in the plug, because there's no fuse in the plug.

[David Simpson]

Craig has hit the nail on the head - Martingdale have an excellent range of mains testing devices, both plug-in or using test leads. Whether folk are just a keen DIY house-wiring guy or a vintage radio enthusiast, I would encourage everyone to at least acquire a M/D socket tester & a M/D lead tester.
I'm certainly not for one second suggesting that folk should dump their cherished DAC90 or whatever. Lets face it - if you use an AC/DC set on DC - you make every effort to ensure that Negative goes to the set's -ve rail or chassis, and that Positive goes to the HT & Heater circuitry. So why cant folk do the same with an AC supply - Neutral as -ve & Live to the Rectifier circuitry. Folk might say - hey, my Bush has the on/off toggle switch in the negative/neutral line. Well, swop it over or fit a 2 pole toggle switch. I've a box full of 2nd hand working toggle switches, (as do many folk) & many 2pole switches are identical in size to s/p & have the same securing thread & hex ring nut.
Lets face it, if someone buys a B & D mains electric drill from an electrical shop & you get a belt off it as soon as you plug it in - you're going to be very annoyed. If you ask a sparkie to PAT Test it & it fails - you're going to be even more annoyed. You'll want your money back, and you might even consider litigation &/or report the shop to Trading Standards.
The following week you flog, on eBay(or, God forbid, on this Forum), a (restored - huh!) DAC90 with a twin lead & have moronically stuck to Bush's ancient live chassis design - that makes you a bigger tit than the shop owner !

Regards, David

[AC/HL]

Anything unmodified, however unsafe intrinsically, can be quite legally bought and sold. Standards are not usually backwardly enforceable. Any problem, and it may only be theoretical, comes if someone knowingly passes it on in an unsafe condition. It's all safe to us, because we have the knowledge to make it so. Once out of our hands, however...

These threads never come to a conclusion.

[stuarth]

Some “Bang up to date” stuff in a metal case (such as a DVD player) is built to current “double insulated” standards, and is not intended to have an earth connection.

Other bang up to date stuff in a metal case (such as some oscilloscopes) is not built to double insulated standards, and the case should be earthed through the 3-core mains lead.

Eddystone AC/DC sets in a metal case (such as described by the OP) were not designed to double insulated standards, and were intended to have the case earthed.

Sets (such as the DAC 90) in an insulated case, if fully assembled with an intact back panel etc, should be reasonably safe with the mains either way round. It is more likely to become unsafe (because a knob came off or the back panel became loose) than bang up to date stuff, so would need frequent monitoring.

For the Eddystone, you really would want the chassis, which is bolted to the case through insulating washers, to be connected to mains neutral, even if the washers seem in good order. And with no earth available and reversible mains plugs, to op is right to consider how to check the mains polarity reasonably continuously. With no earth connection, it would be safer to feed it through an isolating transformer though! Or as a last resort, an RCD (they are not intended as a primary safety device).

Old stuff, used as the manufacturer intended, should be safe enough, provided you can be sure nothing has happened to degrade its safety features. But it won’t be as robust for safety as modern stuff.

Stuart

[bluepilot]

There is a lot of discussion about how much safer we all are now but I was wondering whether anyone has any statistics on how many people were electrocuted in the past compared with now. Probably in the past people were more aware of lurking dangers. For example Hornby produced an electric train which plugged into the mains. The voltage was dropped by a lamp limiter. As soon as you took the engine off the track you had the full mains voltage across the rails. Yards of bare rails at mains voltage. Unthinkable nowadays. Did young boys get electrocuted in their thousands or did they have the common sense not to grab hold of the rails? I once found an old book warning people about the dangers of electrocution. One of them was not to milk a cow when it had its tail wrapped around a live cable. (Why didn't the cow get electrocuted before the milkmaid started milking it?) Another one illustrates what appears to be a particularly nasty way of getting electrocuted.
You can never make things 100% safe but the more nanny state interferes the more people will assume that everything is safe and turn their brains off. Then you get cases of people being sued for things which are quite ridiculous which results in even more "safety features". I recently bought a microwave meal with severe warnings on the packet. "WARNING! Contents will be hot after heating!" OMG, that's even worse than "may contain peanuts". I assume some idiot had burned himself and sued the manufacturer at some time. I wonder where it will end. Be alert. The world needs more lerts.

A bare wire with 200kV on it, dangerous? Not when it is 50 odd feet up on a pylon. Eddystone with live at 240V on it's chassis with insulating washers to the case, safe? Yes if maintained. There is probably more insulation there than in a mains cable. I wouldn't want to spill water on it or any other mains powered radio.

[ms660]

A book with those pictures:

Electroschultz in a Google search.

Checked my fish pie microwave instructions for warnings, the usual cooking time and temperature instructions plus make sure that it's piping hot throughout and leave to stand for one minute before serving, that's about it.

Lawrence.

[bluepilot]

Originally Posted by ms660

A book with those pictures:

Electroschultz in a Google search.

Schutz (protection) rather than Schultz.

Here are a few more of the illustrations:
http://avax.news/educative/Ways_to_D..._Jellinek.html
Don't know who the picture of the rat electrocuting itself was aimed at. Seems like a good way to get rid of them to me.

Originally Posted by ms660

Checked my fish pie microwave instructions for warnings, the usual cooking time and temperature instructions plus make sure that it's piping hot throughout and leave to stand for one minute before serving, that's about it.

I can imaging that a lot of these are genuine:
https://udel.edu/~pollack/Acct350/Ha...g%20Labels.htm

[ms660]

Elektroshulz, I copied it on my note pad next to the PC as Electroschultz....Mind to paper is a difficulty I sometimes have

We have some land that has a fence around a hole in the ground as a warning, there's also a sign saying danger mine shaft keep out written on it, I think that's a good idea.

There's no stopping the idiots and the know alls' but I think that warning signs and notices and H&S/training in general is a good idea for sure for those that can be taught something and long may it continue, I'm pro warning signs etc for a good reason, of which I don't want to go into here.

There were also warnings on the back of some old radio and TV receivers etc.

We had warning signs about live chassis plastered above the workbenches where I first worked, good job too, all the other places I worked at had isolating transformers fitted.

Lawrence.

[dave walsh]

You are absolutely right that [overall] H+S is a basic requirement on balance Lawrence but things can so easily go over the top. During the current viral crisis a [not at all young] woman, used to swimming alone every day of her life, was interviewed by the police on an otherwise empty beach

It's an interesting "fact" that despite the relative inadequacy of commercially necessary live chassis designs and the amount of product sold-it's very hard to find a fatality or injury to the public. It seems to be a problem exclusive to the Workshops but ironically, former staff members are not slow to detail the inadequacy of the working conditions that they tolerated. These days Einstein's comment that "Genius is in short supply but there is no end to stupidity"... is very resonant!

Dave W

"We are idiot's babe! It's a wonder we can even feed ourselves". Idiot Wind Bob Dylan

[McMurdo]

Sorry, I've just read the manual for this set. I was under the impression it was designed with a 2-wire mains lead and happened to have an unearthed metal cabinet and live chassis. What it actually has is a cabinet designed to be earthed, either through the 3-pin mains inlet connector and 3-core cable to an earthed outlet, or, as an alternative, a 2-pin mains outlet and a seperate earth connection to the case. The mains neutral is hard wired to the chassis. The chassis is connected to the seperate earth terminal via an isolating capacitor, and if the 3-core cable is used, a little plug is inserted to connect this capacitor to the case (and hence mains) earth.
In modern parlance we would describe this as an 'earth lift'. It doesn't un-earth the case, only the chassis for signal reasons.

The manual states that 'since this is a live chassis, it is not safe to run the radio with the case removed'.

Either way the manual intimates it's not safe to run without a case earth.

[GrimJosef]

Originally Posted by bluepilot

There is a lot of discussion about how much safer we all are now but I was wondering whether anyone has any statistics on how many people were electrocuted in the past compared with now ...

This subject did come up once before. If I remember rightly the answer was that in the days when equipment safety standards were lower (pre-war and into the 1950's ?) around 10 people a year were electrocuted in the UK. It would be nice to find the original reference though as I'm relying just on my memory for that number.

Cheers,

GJ

[ms660]

Originally Posted by dave walsh

You are absolutely right that [overall] H+S is a basic requirement on balance Lawrence but things can so easily go over the top. During the current viral crisis a [not at all young] woman, used to swimming alone every day of her life, was interviewed by the police on an otherwise empty beach

I could counter that incident with facts from recent incidents concerning the lockdown, people thinking that because they're out somewhere in isolation they can't possibly do any harm but I wont, but as a clue think someone in a self inflicted bad situation to do with the sea then think of the 2 metre distance rule, one of our children works for the NHS, they've all been really struggling.

Lawrence.

[David Simpson]

Over the years I've repaired/restored/owned several AC/DC sets. Two Murphy's - a U122 & a U128 (lovely, lovely veneered cabinets), a Bush DAC10, & a marine Reece-Mace. Whilst in the workshop they were all initially fed via an isolation T/F & Variac. Once I had modified them to modern(3 wire) standards, they were just plugged into my RCD protected mains(PME) sockets. When finished, they were put on display in the L/R on a high shelf(more for keeping grubby fingers off the nicely polished cabinets). Hey - you chaps with precious (but un-modified) DAC90's etc., why not put your sets on a high shelf(but not plugged in) ? So that you can look at them with pride & visitors can ooh & arr over how lovely & quaint they look.
But, & its a big BUT, I've never flogged them. I've given them away to friends who have promised to observe my caveat about keeping them where "little johnies" cant poke at them. One Murphy went to a local heritage museum(minus its 3 pin plug) for just display purpose.
I just think that, lovely as some might be, safety-wise, AC/DC sets have no place as working items in the 21st century. Nor should they be flogged as working items. Fair enough, if one or two vintage radio chums pop round for a blether & a coffee, there is nothing wrong in someone firing-up their AC/DC set on their safely powered workbench, with either AC or DC.

Regards, David

[GrimJosef]

Originally Posted by David Simpson

... I just think that, lovely as some might be, safety-wise, AC/DC sets have no place as working items in the 21st century ...

Perhaps a helpful analogy might be older cars ? I'm thinking of the ones without airbags, ABS, crumple zones, radial tyres, bodywork designed to protect pedestrians better in impacts etc, etc. Should they all be confined to private roads or preceded by a man with a red flag or simply crushed ? Or is it OK to drive them and trade them, making the drivers responsible for doing so safely ? Personally I'm for keeping them running as they originally were, and classic radios too. No-one is forced to buy them.

Cheers,

GJ

[AC/HL]

Can we stay on topic please.

Currently listening to my DAC90A, I feel perfectly safe. And with my engineering head on I know I am safe.

[dave walsh]

It will be obvious to many of us older types but I wonder if some people imagine that AC/DC circuitry was just a peculiar quirk or simply a way of economising on manufacturing costs. I find few people who know that [post war in particular] the erratic nature of various mains supplies in different parts of the country meant a one size fits all PSU had to be devised to keep things going. Eliminating the expensive Mains transformer would have been an the added bonus I suppose. I didn't think about this in relation to the Shipboard equivalent in the sixties but Eddystone had clearly recognised the market existing there with sets like the 870A.

Dave W

Apologies Lawrence [p54] but I was just relating to possible over zealousness like PAT Testing removing all the kettles at work and not really going down any more personal a route. My daughters best friend is a Doctor in London. It is all very difficult.

[Keith956]

There are no sockets in the kitchen in our Regus office since they 'improved' it last year. Apparently someone, in some office, was electrocuted by a kettle. So we now have a kettle on the desk in our office... madness.