Safety in the workshop

[DODGERN]

There are a few points of safety that members with workshops should be made aware of. Many members will be well aware of the following but some new members may find the information helpful.

If your workshop is away from the house, in a shed or garage etc., these safety tips may help to keep you safe.

RCD Protection
Make sure the mains supply to your outbuilding has a RCD (residual circuit breaker) fitted in your workshop. This will detect any electrical leakage in your equipment and should trip the supply, if there is a problem. The trip can then be re-set once you have isolated the faulty equipment.

Mains Isolating Transformer
This should be considered if you intend to use your workshop on a regular basis. This will give added protection as your workshop supply will be isolated from the house supply.

Workshop Flooring
The application of a rubber mat on wooden floors, will keep you insulated from the floor which could be damp. On concrete floors the extra addition of a wooden platform should also be fitted under the mat. These items will insulate you from the ground and give no return, through your body, of electricity to earth, should you receive a shock while working.

Fire Safety
A CO2 fire extinguisher is also a good thing to have. This doesn't have to be a large expensive one. It may stop your shed burning down though!
Do not use a water type for electrical fires but only the CO2 type.

General Safety Tips
Get into a habit of always turning off the supply to your workshop when exiting. Make sure your soldering iron has cooled down prior to leaving. Use a Safe Block connector for testing items without mains plugs. Pushing bare wires into sockets is bad practice. Avoid touching anything that is earthed while taking taking voltage readings on equipment.

Stay safe we want to keep you as a member for a long time!

Roger.

[Andy M0FYA]

Regarding an RCD, which I agree is essential, when I wired my workshop I specifically excluded wiring the lights through the RCD as I concluded that in the event of the RCD tripping I didn't want to be plunged into darkness at the same time! All the mains sockets are through the RCD.

Regarding turning off the power when exciting, I leave an oil-filled electric radiator on all the time (it has a built-in thermostat* and I guess is as safe a heat source as any), so my power sockets remain energised. They are all switched sockets and I religiously check they are all off when leaving (excepting the heater). Also I know that may people leave a de-humidifier powered, any views on this?

(*The thermostat did once stick on, and the workshop was unbelievably hot the next day, but I believe the radiator is rated to allow it to stay powered. A thermostat failure combined with an oil leak could be a different matter however........)

Andy

[fido]

I deliberately didn't fit an RCD in my workshop although it could be argued that it is part of the house anyway, not a remote building. I routinely test equipment using a plug in RCD but sometimes I dry out things like heating elements that have been stored in damp conditions. The damp seeps into the insulation and they would just keep tripping before they could dry out if run on an RCD supply.

[Yorkie]

A very useful and important thread Roger. I do leave the power on in my workshop as I used the workshop (just 10' x 8') for woodturning as well as radio, so I have a dust extractor suspended from the ceiling which comes on automatically for two hours each night. I have a woodturning dust extractor (like a powerful vac) that I used when sanding on the lathe, but the ceiling mounted one helps keep general dust in the workshop to a minimum. recently I bought a small dehumidifier - not much larger than a kettle, with a 0.25 L tank. Given that it's been sunny and warm for several days, I left the dehumidifier on overnight to see if it extracted any moisture in the workshop. Next morning there was at least a glassful, so hopefully, in the winter it will keep the dampness down. The workshop is heated, the walls are insulated and the windows double glazed.

I do have two isolating transformers - one about 1 amp, the other 2 Amps, so more than adequate for radio repairs. I'm always a bit concerned that often, the first radio that novices cut their teeth on seems to be the Bush DAC90A, which is not at all an ideal radio for a first project, because although not complex, it is an AC/DC live chassis. I also wonder if some of the potential safety hazards on the DAC90A are fully understood. For example, often the rubber insulated wire on the dial lights is in poor condition. Although admittedly it's a remote possibility, what if one of those wires came into contact with the speaker frame and hence, the metal speaker grille with the chassis live? I always replace the speaker wiring and dial light wiring - it's not a big job. Furthermore, for me, safety trumps originality every time, and I consider that instead of restorers searching for reversible Bush 2-pin mains plugs on e-bay, they'd be better to consider hard wiring the mains lead to the pot switch to ensure that the correct polarity is maintained at all times. Of course, what tends to happen with e-bay sales of DAC90As is that they're offered without the mains plug so that the onus is on the restorers to put it back into use, then further down the line, lo and behold, the mains plug pops up on e-bay!

Another safety factor is to do as much testing and diagnosis with the set disconnected from the mains, whereas in reality, often, caution is thrown to the wind, the set plugged in to 'see if any sound comes out of it'. A great deal of testing can be done before a set is even plugged in. Visual observation will highlight perished wiring, which will in any event need replacement, which can, and should, be a first priority. I always use silicone covered heat resistant multi-strand wire in vintage colours, which I stock up with from Phil Marrison at the NVCF. Resistors can be checked to see if they're in spec, valve filaments can be checked for continuity, and heater/cathode shorts, transformer windings, coils, OPTs, IFTs and the 'switchery' can all be checked for continuity and against the circuit. If a set is to be 'restored' rather than just 'mended' most restorers will wish to replace all the waxy caps, and if fitted, to replace the mains suppressor cap across the mains input with an X class cap, or at least clip it out. It makes much more sense to do these things before the set is switched on rather than afterwards. If - due to faults - a set draws excess current, and if it has a mains energised speaker, that excess current can burn out the field coil, which has thousands of turns of fine wire. Similarly, mains transformers and OPTs risk being damaged. Sure, a lamp limiter can reduce the risk, but why put the set under stress? Best to use the lamp limiter after the set has been restored - not before!

Often, rather than poking around a set with two test prods, it's possible to use a croc clip on one lead attached to the chassis, then you only have to look what you're doing with the one prod. Personally, I always make a 'cradle' from scrap wood and bracket in which to suspend the upturned chassis to keep it stable, but I know that many restorers just balance the upside down chassis any way they can. The point we should bear in mind, is that we do this for a hobby - not for a living, so there are no time pressures upon us to do a rush job. There are times when we should therefore temper our natural enthusiasm with a little more discretion. There are two definitions of 'amateur' - someone who isn't up to the standard of a skilled professional, or on the other hand, someone who is highly competent and able to work to a high standard, but doesn't do it for a living. Hopefully most of us would aspire to the latter!

Good lighting is also essential, and personally, I have a magnifying Anglepoise style lamp with a circular florescent tube which I often find very useful.

I hope that these observations don't read like a finger-wagging lecture - it's not meant that way, but a lot of heartache and hassle can be avoided by adopting a cautious rather than tempestuous approach.

Or so it seems to me, having learnt a few hard lessons in 'the university of life'!

Have fun,

Night night,

David

[AlanBeckett]

This is in many ways a splendid Thread, but I would observe that safety really depends on taking (personal) care. I would even go so far as to say that the more you rely on the RCD and isolation transformer etc the more you are likely to get bitten. It's the old story, for example with cars; 'I'm protected by my Seat belt, air bags, side impact bars, radial tyres, ABS and Traction Control so why worry?'. When I look at the way a lot of people drive these days I'm not surprised that Insurance Premiums are rising.
Anyway, to get back to the topic in hand, I think the fundamental requirement for the safe repair of this old valve based equipment lies between your ears. The three rules are 'Be careful', 'Be careful' and 'Be careful'. I know that I, and other old codgers, cut corners, and do things automatically because we've been doing them for (in my case) some 55 years. In many cases it's difficult to describe how and why.
So, stick to the three rules.
Alan

[ppppenguin]

I don't have an isolating transformer as each socket on my bench is powered via an extension so I can isolate individual sockets.

This is using the word "isolate" in 2 very different senses. The two are far from equivalent. And please get an RCD - they are cheap and effective.

I agree that you shouldn't rely on an RCD or isolating transformer. They are there as an extra line of defence in case something goes wrong. Just like being sensible with your net usage and not relying on anti-virus software as the first defence.

In the OP there was a suggestion that an RCD and isolating transformer might be used together. There is nothing wrong with doing this but the RCD won't work. My bench is RCD protected but I use a TX so that I can safely connect earthed testgear to live chassis radios and TVs.

[Yorkie]

... It's the old story, for example with cars; 'I'm protected by my Seat belt, air bags, side impact bars, radial tyres, ABS and Traction Control so why worry?'. When I look at the way a lot of people drive these days I'm not surprised that Insurance Premiums are rising.

I recall a Police accident investigator saying there's no such thing as 'accidents' - only 'incidents' and that in fact is what the police now refer to them as. The officer sad that in his vew, motorists are basically selfish, care nly about their skin - not other rad users and feel impregnable in safefey cages,crumple zones, ABS braking, air bags, seat belts, and he suggested that that if all of these devices were removed, and instead, a 6 inch spike fitted to the centre of the steering wheel, so-called 'accidents' would plummet as any risks would then be based only on Darwin's theory of the 'non-survival of the stuplidest'.

But we do occasionally get complacent and tired and make silly mistakes. Last year I got a 500V belt off a voltage doubler in a capacitor reformer, and boy, did that liven me up. Luckily it's 'Volts that jolts - Mils that kills'. Ordinarily I'm so cautious that not only do I switch stuff off that I'm working on, I disconnect it. I'm too young to die, and too old for nasty shocks, so it remains fresh in my mind.
Whoooeeee!

David

[tiv48]

just a note on live chassis.from the early 80s tv sets started to use bridge rectifiers with one leg of the bridge connected to the chassis .so the chassis was always 1/2 live no matter wich way round the mains was connected
rob t

[ppppenguin]

just a note on live chassis.from the early 80s tv sets started to use bridge rectifiers with one leg of the bridge connected to the chassis .so the chassis was always 1/2 live no matter wich way round the mains was connected
rob t

An RCD will trip if you touch something you shouldn't but the only sane way to hook up test gear is an isolating TX.

[Joe]

The best test gear is your own senses. You can tell a lot from how things look, how hot they get, how they smell &c.

I'm with Alan on thinking that too much safety gear, and not just in this field, can make you complacent.

As with so much different people have different ideas and attitudes to risk and we all have to find the balance which suits us.

David speaks sooth about preliminary tests and that is also about the safety of the set. I know that if I get a belt it will most likely result in nothing worse than a bit of bad language but a transformer going bang would be a much more difficult thing to sort out.

The other thing to keep in mind is that it isn't just our own safety that we have to think about. I have to keep reminding myself that, for all I'm only fixing things for myself and live alone, if I walk under a 'bus other people will get hold of my things who wouldn't know that they may have safety issues.

- Joe