A Tale of Woe - A Lesson Learnt

[ericmark]

This sort of problem is not only with houses. I was told to remove un-used wiring in a concrete factory. The old electrician came and identified the un-used wiring and of course I also tested all cables with a test lamp including using a proving unit. And they were all dead. With a concrete factory in some areas all one could do was to saw through the cables as firmly concreted in. One junction box without lid was also to be removed and from the state one would assume it had not been live for years.

So all going well until I returned from tea break lucky. At which point I am told cable sparking and the auger was not working. Seems it was just one item from old plant which had been retained. Cable joint and alls well. However once this near miss had happened it was decided that cables would only be removed when plant was not is use.

But it is all too easy to make mistakes with old cables.

As to PIR with un-identified circuit I would disconnect the cables and insulate in consumer unit ready to re-connect if it was found latter something didn't work. But PIR's done on a budget likely this could be missed.

We are all told we should drop the tails and switching of a MCB and using tape over lever is not enough. However it is some times not possible to isolate else where so one way or the other one has to break the rules. be that pull the DNO fuse, work on a board live, or just put tape on the MCB one has to break the rules. I do have locking clamps but not for all makes of MCB and they will not fit some consumer units. And one is hardly going to leave a locking clamp on a MCB as a permanent isolation.

Yes DNO should provide an isolator but often they don't so we break the rules.

In the past I have also used tape inside a locked cover so in theroy only another electrician could turn it back on. However again a near miss when a mechanic had wangled a key off some one and turned the power back on taught me in my early days to drop tails.

So yes likely a PIR would have missed the problem. However it would have raised the point about buried cables and RCD protection and maybe the new owner would have had the consumer unit changed to one with all outputs protected by RCD.

And that is really the point. No matter how careful one is accidents will happen. So using RCD's is really the only way to protect from this type of accident.
Having said that I sawed through a lighting cable going horizontal across the wall while fitting a water supply to fridge. In spite of all RCD protection it still knocked me out for few minutes. As to if I let go of the twin hack saw blades being used to cut the channel I don't know. But I could not really blame the electrician who ran the wires horizontally between a pair of two way switches as it is permitted. It was my fault for not using a cable locator first. I did test RCD and yes it did trip before 30ma and within 40ms but still got one hell of a belt.
Worst bit was my pride. How had I an electrician made such a silly mistake. But it happens and I can see reason for 50mm rule.

 

[ccam108]

This sort of problem is not only with houses

A youth club I help out with took over an empty shop unit in the shopping centre a couple of years ago. I was fitting a few projectors etc and noticed a couple of lighting circuits weren't working (turns out it was a dead contactor). When sussing out what did what in the unlabelled DB I noticed there were two 32/3 breakers and two 4core 6mm SWAs - one fed the air-con and the other was undetermined, but switched on. Turns out after tracing the cable, it ran the whole length above the ceiling and the end was dropped down a small wall void next to the front windows with the sawn off end masking-taped. Luckily it didn't hurt anyone but that could have been very dangerous if someone came to replace the windows and exposed it, and who knows how long it had been there.

Colin C

 

[ban-all-sheds]

So using RCD's is really the only way to protect from this type of accident.

Nope.

An RCD will do nothing for you if you put parts of your body between line & neutral.

 

[JohnW2]

An RCD will do nothing for you if you put parts of your body between line & neutral.

Indeed. Unless and until we have electrical installations intelligent enough to visually (or otherwise) inspect a load prior to allowing current to flow in order to determine whether it is a human being or some other 'undesirable' load, nothing will protect anyone who connects themselves between L and N!

One day, the general public may come to understand this, but I doubt whether it will happen unless there is a determined campaign to educate them.

Kind Regards, John.

 

[ban-all-sheds]

One day, the general public may come to understand this, but I doubt whether it will happen unless there is a determined campaign to educate them.

Do a cost-benefit analysis of such a campaign.

 

[JohnW2]

One day, the general public may come to understand this, but I doubt whether it will happen unless there is a determined campaign to educate them.

Do a cost-benefit analysis of such a campaign.

If you're trying to press my buttons, you've hit a good one there

As I've often had to explain to people when they've tried to induce me into such activities, no matter how rational and how scientifically/ statsitically sound the exercise may be, any politician or professional who becomes associated with a cost-benefit analysis in which human lives are on one side of the equation are at serious risk of comitting polical/ professional/ whatever suicide!

We all know that certain risks are allowed to persist because the cost of removing/reducing them would be very large in relation to 'the few lives' that would otherwise be lost - but (s)he who stands up and actually says that 'not enough lives are being lost' to justify the cost may well be heading rapidly towards a premature end of their career! Society just doesn't want to hear that being said, even though 'eveyone knows it'.

Fortunately, it's usually adequate (and true!) to argue that the exercise "can't be done", because it's impossible to put a monetary value on a human life!

Having said all that, I don't actually think that it would necessarily cost all that much to take some simple measures to improve public awareness of the limitations of RCD protection - so there is probably some potential for saving a few lives/injuries at relatively low cost, even though the number dying because of this ignorance is undoubtedly extremely small.

Kind Regards, John.

 

[ban-all-sheds]

As I've often had to explain to people when they've tried to induce me into such activities, no matter how rational and how scientifically/ statsitically sound the exercise may be, any politician or professional who becomes associated with a cost-benefit analysis in which human lives are on one side of the equation are at serious risk of comitting polical/ professional/ whatever suicide!

People, especially people of political career persuasion, are irrational.

We all know that certain risks are allowed to persist because the cost of removing/reducing them would be very large in relation to 'the few lives' that would otherwise be lost - but (s)he who stands up and actually says that 'not enough lives are being lost' to justify the cost may well be heading rapidly towards a premature end of their career! Society just doesn't want to hear that being said, even though 'eveyone knows it'.

Maybe that's where your determined campaign of education should be targeted.

Fortunately, it's usually adequate (and true!) to argue that the exercise "can't be done", because it's impossible to put a monetary value on a human life!

1) It can.

Simply by doing it, you have done it. Argue if you like about the figure, but there are figures which are used.

2) It is. Look at the judgements of NICE, for example.

And trawl through some of these:

http://www.google.co.uk/search?q="r...rGswbCntzwDQ&ved=0CAcQpwUoAQ&biw=1305&bih=659

you'll find values.

there is probably some potential for saving a few lives/injuries at relatively low cost, even though the number dying because of this ignorance is undoubtedly extremely small.

I'll press another of your buttons.

This one bears the legend "Statistical Significance", and tells you that there is no theoretical or empirical way to prove potential for saving a few lives/injuries....

 

[JohnW2]

2) It is. Look at the judgements of NICE, for example.

Arrrggghhh! - now that is just about my ultimate button (but the degree of flak they attract is perhaps illustrative of the point I made)

And trawl through some of these:

I don't really need to; I'm intimately (and in some cases painfully) familiar with an awful lot of that!

Kind Regards, John.

 

[Stoday]

NICE values life at around £30,000 a year ("Quality Adjusted Life Year).

Interestingly that equates to the cost of a patient with cronic kidney disease, needing hæmodialysis three times a week to stay alive.

The UK could not be the only 1st world country that refuses treatment to patients with kidney disease. So, in my opinion, that sets the threshold.

 

[mointainwalker]

The only time when I have ever seen a monetary value put on saving lives was years ago ( 10- 15 ? ) when there was a debate about trains jumping red signals and the systems that existed to stop trains in those cases.

At the time it was said that the cost was x million and the latest sysem had not been implemented because it was not financially viable based on BR/train company valuation of 500K for a life.

 

[SimonH2]

Well in various areas, a life does have a value put on it (even if indirectly). I don't know what the figures are, but for road planning, there are established figures for the cost of an accident with serious injuries, and one with fatalities. Though it isn't quite the same thing as putting a value on a life, it comes close since it factors into the "is it cheaper to accept the accidents or to implement <whatever is being proposed>".

Everyone knows this goes one, but if it ever comes up then it's usually all "oh no, must save every life whatever the cost" - especially if ones reading choice tends to the Daily Wail end of the spectrum ! It is of course why we've got such bad laws in areas like cartoons depicting minors - and of course the absurd (to a sane person) case of someone going to court over a cartoon of "Tony the tiger".

As already pointed out, the danger is if people find out that you've made that decision. I/m sure it comes up in (for example) car manufacturing all the time, but whenever it does, I doubt anyone fails to remember how Ford came unstuck with the Pinto. In case anyone doesn't know, the Pinto had a design flaw in that a rear-end shunt could make the petrol tank burst and envelop the car in a fireball - a memo leaked which stated that it was "cheaper to let them burn" (ie payout compo for the rare occasions) than to re-engineer the car.
More lately, just look at the flak Toyota took for the allegedly sticking throttles. The case that was held up as "proof" was supposedly the off-duty policeman in the US who called his colleagues and so the event was captured by their call recording. I was reading only last week ... that the cause was eventually determined to be a badly fitted mat supplied by the dealer. Trouble is, the media are happy to report how "Toyota kill this family" but don't care (because it won't sell papers) when it was found out that Toyota weren't at fault.

 

[JohnW2]

The only time when I have ever seen a monetary value put on saving lives was years ago ( 10- 15 ? ) when there was a debate about trains jumping red signals and the systems that existed to stop trains in those cases. At the time it was said that the cost was x million and the latest sysem had not been implemented because it was not financially viable based on BR/train company valuation of 500K for a life.

Indeed - that is a classic case which is nearly always raised when this issue is being discussed these days.

It also illustrates a fairly 'safe' course for those of us who have to handle such data. If one merely presents an estimate of 'cost per life saved', it then falls to others, if they are brave enough, to draw and publically utter the conclusion that the cost is not justified by the benefit, if that's what they believe.

Of course, particularly in commercial environments (like trains), there is more than just saved lives on the 'benefit' side of the cost-benefit equation. Deaths or, often far worse, injuries resulting in devastating life-long incapacity in young adults, can result in very large compensation awards - so avoiding such liabilities can be viewed as a distict benefit - by insurers, even if not directly by the companies themselves.

Kind Regards, John.

 

[JohnW2]

Apolgies for delay in responding to this; I've been fairly tied up today....

NICE values life at around £30,000 a year ("Quality Adjusted Life Year).

Yes, that's correct (as a 'maximum'), although some people feel it should be closer to £40,000 per QALY; NICE themselves use different figures in different situations and it's likely that their figure will rise in the fairly near future. However, the concept of cost-per-QALY was never really intended for use in the sort of cost-benefit analyses that BAS challenged me to undertake in relation to public education about RCDs.

Cost per QALY does not have to be anything to do with death or 'the value of a life', per se. As the name suggests, it's more a measure of 'the value of health'. For example, if a treatment does not alter life expectancy, but improves the 'quality of life' from 'half-perfect health' (0.5 QALY per chronological year of life) (and, yes, 'measuring' that is the big problem!) to 'perfect health' (1 QALY per year of chronological life), then that represents a benefit of 0.5 QALYs per year - hence 'worth' about £15,000 per year according to NICE's current formula. When first conceived, QALYs were not about money at all but, rather, evolved in attempts to compare different treatments (or no treatment) in terms of 'what was best for the patient'. The problem there is that different patients have totally different attitudes - some feel that one year of perfect health (followed by death) is better than 5 years of not-too-good health, whereas others feel the opposite; attempting to take into account that variation in individual's philosophy leads to the concept of what are called individual 'utility functions'.

Anayway, although not really intended for this purpose, if we extend this concept to the death by accidental electrocution of a young fit person, then the numbers get fairly large. I haven't got the relevant tables to hand, but a fit 30-year old male is probably considered to have around 50 QALYs potentially ahead of them (50 years of perfect health, or more than 50 of less-than-perfect health) - so the 'cost' (loss of QALYs) resulting from their accidental death at age 30 would be assessed as about £1,500,000 on the basis of the current NICE formula.

Kind Regards, John.

 

[ban-all-sheds]

OK - fine.

£1.5M is a number to work with.

If a safety/regulatory measure is going to prevent the loss of 2 such lives per year then it is not worth doing if it costs more than £3M per year.

Blindingly obvious, blindingly simple.

 

[JohnW2]

OK - fine. £1.5M is a number to work with.
If a safety/regulatory measure is going to prevent the loss of 2 such lives per year then it is not worth doing if it costs more than £3M per year.
Blindingly obvious, blindingly simple.

Spot on! In mathematical terms, if you accept all those figures (and the NICE 'valuation'), then that's the answer. The catches:

1...It is too all intents-and-purpose impossible to estimate how many lives might be saved by any particular measures. Indeed, we can't even be certain that there are currently any losses of life due to the reason we're discussing - and if there aren't then there obviously would not be any lives to save, no matter how much money one threw at the matter! (i.e. the 'cost per life saved' would be infinite)

2...If you had magical powers and found some way of overcoming (1), as I said before (s)he (or maybe his/her political party) who stood up and said that they knew how to save X lives per year, but weren't going to do it because it would cost more than £1.5m per life saved, would be in for a hard time!

Kind Regards, John.