Thoughts on safety aspects

(still in preparation)

 Over the years, as in many walks of life, regulations have increased in number and complexity. A few years ago a regulation was due to be introduced to stop any electrical equipment from being sold without a moulded-on 13 amp plug. Why? Well presumably because people are not to be trusted to fit their own plugs any more. In fact it was proposed to become illegal to sell stuff if it was fitted with a re-wirable 13 amp plug. The basis of the new regulations is a European Ruling called the "Low Voltage" directive. There are others too, dealing with electrical equipment owned by the Landlord in rented accommodation. Unfortunately, once someone believes a regulation is needed that regulation must be absolutely "cast iron". It has to be exhaustive in content otherwise it isn't worth bothering about in the first place as it would naturally supersede simpler rules which may be based on common sense rather than specifics.

Fortunately, pressure groups managed to get the moulded-on plug directive ditched.

A friend asked me to design an equipment which could be used in a school physics lesson to demonstrate 13 amp plug wiring. A red lamp had to illuminate if the wiring was wrong and a green lamp if it was OK. It worked but it wasn't easy to come up with a design! How many different ways are there of wiring, or making a mistake in wiring, a 13 amp plug?

guess then click the little devil to see!

It had been planned that old stock with detachable plugs could be sold for a period after the new regulations came into force on the first day of 1998 but as you may have noticed, a side effect of all this was to eliminate second-hand electrical goods from being sold by charity shops. Old electrical goods, if you can find any, are usually now sold with their lead cut off and possibly a notice stuck to the top stating that the equipment is "sold for spares". I find this result to be self-defeating as people that might have been able to fit plugs correctly have some difficulty fitting new leads. It certainly does happen. Recently I was presented with a TV for repair whose "new" lead had been fitted to the cut end by the expedient of baring three leads on the new cable, baring two leads on the cut end and twisting them all together. A generous dollop of insulating tape completed the fix. Naturally the plug fuse was open circuit. I understand that "car boot sales" are excluded from the regulations and here anything goes.

Later, it was decreed that if a second-hand item with a mains input was sold through a retail outlet it had to be tested for safety. Essentially this means that any exposed metal must be wired to the earth pin of the mains plug. Unfortunately this adds a relatively considerable cost to the item as testing doesn't come cheaply.

This safety decree also extended to electrical equipment used in a place of work and now everything you'll see in a retail shop for example will have a label indicating it's passed a safety test.

One of our local recycling centres has recently (August 2004) stopped accepting TV sets at their dump. TV sets as everyone knows are hazardous waste under a new European Directive. Either this is left to interpretation, as a second dump still accepts TV sets, or the ruling hasn't filtered through to them yet... time will tell? Next time a customer approaches up our driveway staggering under the weight of his defunct Sony Trinitron, I'll don my NBC suit and meet him half-way to the workshop and hose him and the set down to prevent contamination. After all, if I was to declare the set BER, it would become a candidate for the local dump and thus automatically become hazardous. Actually I believe its something to do with the screen phosphors being declared unsuitable for landfill. What then will happen to old TV sets? I suggested to my better half that I'll be digging a big hole in the back garden soon (in the dead of night of course). A wonderful solution came about when CRT televisions were abandoned and flat screen sets universally introduced by manufacturers. This is a fantastic break for TV manufacturers as the market was totally saturated with CRT sets.

Safety-wise, what to do with old radios brought for repair then? Well in the case of AC/DC sets like the early Pilot Little Maestro there are numerous instances of metalwork, potentially at live mains voltage, easily accessible to fingers. For example, take the mains lead (not of the Pilot which used a special line cord) which is usually two core. The wires are rarely identifiably colour-coded so that one cannot tell which of the two connects to the chassis, hence a refitted plug may result in a live chassis. Each knob may have a partly recessed grub screw and under the case is a set of fixing screws whose heads are exposed. A knob may loosen and fall off and suddenly a live spindle is available for the unwary to touch. Many sets have a chassis mounted two pin plug which is unpolarised and if the original lead is present can be removed and reversed. This enables the chassis to be randomly at either mains neutral or mains live. At the rear of a set, if the back is actually fitted (and it may not be) are ventilation holes and, if the back is badly warped, quite large apertures, through which metal tools may be poked. Internal aerials are often used on AC/DC sets, although sometimes an external aerial must be fitted. In the latter case a capacitor will be the blocking medium, stopping direct connection to the chassis. Old capacitors leak and also, even in excellent condition will naturally pass AC. The larger the capacitance the larger will be the alternating current which will pass when the aerial is grounded. If grounding is via a human appendage then a shock, the magnitude of which, depending on lots of factors, will result.

I suppose one has a duty of care. If a set is brought for repair and there is any safety aspect which differs from modern practice then the customer ought to informed in writing about the potential danger. Take the instance where a set has been used since new by a customer and a valve needs replacing. Some learned authorities may advocate cutting off the mains lead and handing back the set. Could this be construed as criminal damage? Say the set cost £500 and you cut off its mains lead? Say it was working reasonably well and it needed only the volume control knob tightening and you cut off its mains lead and handed it back. In all cases it is indeed criminal damage. It would make more sense to say "I've fitted a new UL42 valve but please be aware that the set can be dangerous if one handles the knobs with wet hands etc". What if the set had been fitted with a new UL42 and the owner, being so pleased with the improved tone, had carried it into the bathroom and subsequently been electrocuted? "I remember", says a friend of the deceased, "Bloggs Radio just fixed that set... it must have been something they did to it! He had it since 1951 and it never electrocuted him before". At least Mr Bloggs could point out to the Coroner the warning notes on the invoice!

If one is really unsure of one's ground a card label could be slid over the mains lead and positioned over the pins of the mains plug. The card could be printed with a suitable warning about the equipment "not complying with modern standards etc."

I'm still thinking.......

 

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