Metamec electric clocks. Unsafe?

[Robsradio]

Maybe people will clear them out... time to look out at car boots and charity shops and save them!

[G.Castle]

Originally Posted by Robsradio

Maybe people will clear them out... time to look out at car boots and charity shops and save them!

I was thinking that.

Logic and common sense do not exist in the modern world.

[McMurdo]

Here's a movement 'in storage'.

The bobbin is on a plastic former mounted on the laminations, which are connected with the rest of the clock; however the hands are all mounted on nylon sleeves and the only mounting of the mech to the case is to the perspex or acrylic body via deeply-set countersunk screws, themselves covered by the clock face. That's all then sealed behind the glass which is bolted to the same perspex body. Impossible to touch anything that might potentially become live in the event of a primary insulation breakdown (eg coil to laminations). It's almost double-insulated.

The clock dates from the late 60's.

[Mike Phelan]

Originally Posted by Nickthedentist

Mike, I’m not sure if I’m misunderstanding what you sad, but are you really suggesting rewinding the coil on an already-working movement?

Not if it's already working, Nick. I was really referring to a clock that had stood in the shed for decades

[Nickthedentist]

I see, that makes perfect sense now

[stickfly]

Thanks to all of you that have replied.
My two clocks are running well on the replacement mains cables fitted, they have 1 amp fuses in the plug and the coils look pretty good.
I don't think I'll fit an earth system even though the clock wind & adjust mech's are metal.
Lovely clocks that keep perfect time.
Regards ..... Gary

[Robsradio]

Originally Posted by stickfly

Thanks to all of you that have replied.
My two clocks are running well on the replacement mains cables fitted, they have 1 amp fuses in the plug and the coils look pretty good.
I don't think I'll fit an earth system even though the clock wind & adjust mech's are metal.
Lovely clocks that keep perfect time.
Regards ..... Gary

That's good to hear, enjoy them, you can thank the National Grid for the good timekeeping ;-)

[Nickthedentist]

...and curse it on the odd occasion when it all goes wrong!

https://www.vintage-radio.net/forum/...d.php?t=137419

[Robsradio]

Originally Posted by Nickthedentist

...and curse it on the odd occasion when it all goes wrong!

https://www.vintage-radio.net/forum/...d.php?t=137419

IIRC that error was never fully corrected and I had to manually change the time in the end, it’s all be good in recent years thankfully.

[Oldmadham]

Originally Posted by Cathovisor

Never had a problem with any of my Metamec clocks.

I was greatly amused by the concept of electrical safety in Australia as Australian mains plugs are probably the very worst I have encountered in my travels with their thin little blades.

They are perfectly adequate & have been used successfully for many decades.

[Oldmadham]

Originally Posted by paulsherwin

Opinions do differ a lot on the safety of old synchronous clocks. The predominant view is that they are acceptably safe if used sensibly, but there is a minority view that they are inherently unsafe and should only be used if rewound for low voltage operation.

Remember that touching a live electric clock will very rarely be fatal anyway as your body won't be earthed. (You'll certainly know about it though )

It's true that Australia has a strong electrical safety culture. Strict regulations were used as a way to discourage electrical imports in the 50s and 60s, a form of economic protectionism.

It wasn't logical in the days before RCIDs to not earth metal cased devices, as the only protection offered was the Fuse at the "Fuse box" where the Mains entered the building.

If the clock is a wall mounted device, they would mostly be approached "in service" using a ladder or "standing on a chair".
A "zap" in such circumstances may well cause injury, including, if you fall just the wrong way, death.

[Oldmadham]

Originally Posted by G.Castle

I have one. (A local product i believe), they're not perhaps up to todays safety standards, but if run through a rcd protected supply and you use a one amp fuse in the plug/spur then they are no worse than any other vintage gear. I can't see how they could be a major fire risk. An insulation test may be an idea if you want to put your mind at rest.

It's in the Australian culture that consumer items should be powered from double wound transformers and have the crap earthed out of them, but then I don't know if they had a bigger prcentage of house fires caused by burning transformers than perhaps Europe or the USA?

I have three core mains flex on mine as it seemed the sensible thing to do.

Regards,
Greg

Only radios, TVs and other such "Electronic" equipment used "double wound" transformers.
Other metal cased electrical equipment had Earth connections as standard, but used direct Mains connections.

If was not uncommon in Australia for houses to be supplied with 3 phases.

In the (maybe unlikely) event that two different phases were present in the same room feeding different GPOs, & devices operating from them had Active to case shorts, you would have full phase to phase voltage between them.
If the metal case is earthed, both devices will blow the fuses feeding them, & there will be no danger.

If, in the case of both GPOs being on the same phase & one has an earthed metal case & the other not, if the latter has an Active to case short, touching both simultaneously is dangerous.

As far as radios, in particular are concerned, at the end of WW2, Australia did not have the plethora of different power supply systems the UK & Europe had, so did not have the requirement for the radios to be usable on both AC & DC Mains.
We also didn't have 110v Mains, which in the USA made "series string" heaters a lot easier to implement than in 240v countries.

What we did have was valve manufacturers who had vastly ramped up their manufacturing capabilities of 6.3 volt valves during WW2, so instead of setting up new production lines for "series string heaters", it made solid economic sense to use power transformers & produce "ac only" radios for the mass market, with the few DC Mains areas, being regarded as "niche" markets, where special radios using imported "series string" valves could be used.
Interestingly, most such radios used "figure 8" cable, as with the Mains confined to the on/off switch & transformer primary, there was little danger of a Mains to chassis short.

Power transformer design was a mature technology, & fires caused by burnt out transformers were pretty much unheard of.
Transformers stink when they burn out, so in a domestic environment will soon be detected, whilst in commercial service, electronics with power transformers have run continuously for decades.

Yes, transformers did fail, but not catastrophically, & were just replaced & the equipment put back into service.

[Maarten]

Semi-offtopic: Isn't there more than just tradition to the tendency of Australian equipment to use mains transformers? Philips did a specific redesign of their non-mains-isolated buck converter topology power supply in the K9 TV chassis to make it mains isolated for the Australian and NZ market.

[Station X]

Time to close this thread. It's drifted way off the safety of electric clocks.