Electrical deaths

[Bushmiller]

Early on in the thread some reference was made to electricians being involved in a high proportion of deaths by electrocution. Not surprising really as they are the people in most contact (oops, sorry) with the stuff.

I think live working is fairly common, although not preferred, in many branches of the various electrical trades. Live line working is common on the transmission lines. I went looking for a video, but couldn't find it quickly. The one I saw was in Canada I think where a chopper dumps the linesman on to the wires so he can perform the maintenance.

I think the essence of working with an invisible product is to have a very firm idea of what you are doing and have systems in place to protect you if things go wrong. At work the sparkies working on high voltage gear have rubber mats they operate from, they have an offsider with emergency rescue apparatus and they have usually thoroughly researched the job before tackling it.

However, things can, and do still go wrong.

Regards
Paul

[Mobyturns]

Most folks don't realise they can be killed by lightning striking the ground near them. The million+ V lightning strike sets up brief areas of potential difference (voltages) on the ground around the strike. If one of your legs is in the 100,000V area and the other is in the 10,000V area, then you have 90,000V between your legs

Its interesting your point about lighting. I worked with a dutch engineer back when I was an apprentice, and he told me about an issue like that that occurred with grounding at a power station They shut a whole area off to public both on land and at sea due to electrocutions from difference in soil and water conductivity.

So in a thunderstorm its better to stand on one leg? & when near power stations, switch yards etc to hop about?

In times past our climbers / riggers would "jump" onto & off masts & towers that had "broadcast" equipment (AM/FM TV etc) on them for that very reason.

Seriously though you both raise very good points about the potential difference - "Voltage, electrical potential difference, electric tension or electric pressure between objects" even static discharges from things not thought to be "alive" - vehicles at petrol bowsers etc.

[BobL]

So in a thunderstorm its better to stand on one leg? & when near power stations, switch yards etc to hop about? .

Yep, mountain climbers on exposed slopes are advised to squat on one leg during thunder storms. Not that easy to do.

[AlexS]

BobL, your point about lightning creating a potential difference for a radius about the strike point is spot on. In fact, I understand that the majority of deaths from lightning strikes happen this way. Certainly, with stock, it's common for them to die when sheltering under a tree that is struck.

[BobL]

Early on in the thread some reference was made to electricians being involved in a high proportion of deaths by electrocution. Not surprising really as they are the people in most contact (oops, sorry) with the stuff.

In terms of total numbers this is not correct and their industry goes to some pains to point this out and use it to keep the current regs in place. Only about 5 % of electrocutions are to electricians. The majority, 54%, are to other people on the job, so ~50% are to other workers, e.g. tradies, insulation installers, crane drivers, supervisors, inspectors etc.

In terms of the numbers of deaths relative to the total number of people involved in a specific trade, more sparkies are indeed electrocuted than say plumbers, or truck drivers. One issue is the cause of electrocution is not always clear. An insulation installer may have accidentally touched a live wire in a roof cavity but was he/she taking too big a risk operating in low light or was the original wire poorly installed? Of course it would have been smarter to simply turn the power off at the switchboard and I note that is now a requirement for any trades (except electricians) entering a roof cavity.

[Mobyturns]

In terms of total numbers this is not correct and their industry goes to some pains to point this out and use it to keep the current regs in place. Only about 5 % of electrocutions are to electricians. The majority, 54%, are to other people on the job, so ~50% are to other workers, e.g. tradies, insulation installers, crane drivers, supervisors, inspectors etc.

In terms of the numbers of deaths relative to the total number of people involved in a specific trade, more sparkies are indeed electrocuted than say plumbers, or truck drivers. One issue is the cause of electrocution is not always clear. An insulation installer may have accidentally touched a live wire in a roof cavity but was he/she taking too big a risk operating in low light or was the original wire poorly installed? Of course it would have been smarter to simply turn the power off at the switchboard and I note that is now a requirement for any trades (except electricians) entering a roof cavity.

Or was the installation interfered with after install? or did it suffer degradation from inferior product insulation, rodent attack, mechanical damage from storing objects in the roof cavity? Many things to consider.

[Bushmiller]

I do despair a little at the quotation of statistics, which of course I use too and therefore I am equally guilty, because they are a bland, unexplained figure.

They do nothing to explain the circumstances behind the events. For example, an electrician is working on the incoming connection to a house while standing on a ladder (because the wire is 6m in the air): he gets a shock and falls off the ladder breaking his leg. Is that injury attributed to the danger of ladders or electricity or both (which in itself would double the number of events )?

Many of those incidents related to the so-called "insulation scandal" would have emanated from the old style of wiring, which with age became extremely brittle. As soon as it was disturbed, it broke and bared wires. Then they came into contact with aluminium foil and we have the recipe for disaster, particularly as houses with that style of wiring would not have had a safety switch.

We had an incident at work where an indication lamp on a switch board was replaced. Unfortunately the wrong voltage bulb was selected and when it was inserted it caused a flash that resulted in burns to the person's hands. That person was an electrician and he was mortified that he had made such a mistake. He was also unlucky in that the switchboard itself was poorly designed without adequate protection against such incidents.

We had yet another incident recently where a contractor during outage work was cutting a large pipe in the boiler with a plasma cutter. As the pipe was large he enlisted a mate to support the piece being cut off. As the cut was being completed the mate suffered an electrical shock, which allegedly exited through his head! It was reputed that the plasma cutter was capable of delivering this injury.The details of this incident are still being investigated, but he reported to the first aid, it was noted that he had two wounds on his head and he was shipped off to the local hospital for further testing and monitoring.

Personally, I am doubtful of the circumstances of the "electrical shock," or indeed whether it was a shock, but I expect it will go into the statistics.

Regards
Paul

[Vernonv]

Personally, I am doubtful of the circumstances of the "electrical shock," or indeed whether it was a shock

There is a good chance it was -
1. I believe plasma cutter use quite a high open circuit voltage.
2. If the ground clamp was on the fixed end of the pipe (hence earthing that side), when the pipe was cut through, the helper may have become the "earth" for the loose end ... if only for a brief instant.

[BobL]

There is a good chance it was -
1. I believe plasma cutter use quite a high open circuit voltage.
2. If the ground clamp was on the fixed end of the pipe (hence earthing that side), when the pipe was cut through, the helper may have become the "earth" for the loose end ... if only for a brief instant.

Yep, my PC came with very specific instructions about earthing requirements and states that it is capable of giving the operator a decent jolt if this is not attended to.

[Bushmiller]

Thank you Bob and Vernon. It is in fact this information that I have been trying to find. A quick search on Google revealed nothing untoward regarding plasma cutting and the potential for electric shock.

I still find it slightly implausible that the helper could have received an electric shock that exited through his head without undue consequences. The boiler maker suggested he get checked out and the helper went completely unaided to the first aid officer.

Strange things do happen.

Regards
Paul

[BobL]

In a somewhat timely - or untimely - manner, in between this post and the last one, I was using my PC to cut out a 210 x 250 x 8 mm plate and after cutting two sides I had to reposition the plate. Went to strike an arc and instead got a slight jolt. turns out I forgot to reattach the earth to the workpiece. It was much less than a spark plug sort of jolt but it was definitely there.

[Bushmiller]

In a somewhat timely - or untimely - manner, in between this post and the last one, I was using my PC to cut out a 210 x 250 x 8 mm plate and after cutting two sides I had to reposition the plate. Went to strike an arc and instead got a slight jolt. turns out I forgot to reattach the earth to the workpiece. It was much less than a spark plug sort of jolt but it was definitely there.

Bob

There are clearly some issues with the device. I have only once used a plasma cutter to cut a piece of heavy stainless pipe: That was twenty years ago so I am completely unfamiliar with the machine.

Your "tingle" sounds very much less than a full blown passage of electricity through the body. I really hate electric shocks so take great precautions with the likes of removing spark plug leads while the motor is running and fiddling with electric fences. However, those are primarily voltage issues while it is the current that is normally the life threatening component and that danger increases with the rise in amps: The exception being that teeny milli amperage that interferes with the heart rhythm! I think it causes ventricular fibrillation.

Nevertheless, it is all a little disturbing.

Regards
Paul

[.RC.]

If it is illegal to do any electrical or plumbing work, the fittings should NOT be on sale in retail outlets but rather available only to qualified people on production of their appropriate licence.

Also it is not illegal everywhere, some states it is legal for people to fit plugs to cords... Other backwards states like Qld it is fully illegal..

I do my own minor electrical work, I do not touch fuse boxes or anything...

But an electrician is a long way away from here and costs a fortune just in travel costs... Plus I have seen plenty of dodgy work electricians do... At the moment I have discovered in the main meter box I have two sheds, one has a fifty amp breaker, the other a 35 amp.... Except they have been wired incorrectly, the shed that should have the fifty amp breaker is obviously on the 35 amp one as it is the one that clicks down sometimes when I run the welder...

I had three phase sockets incorrectly wired, some motors ran backwards on one plug, forward on the other.

In the house we had a power wire on a freshly installed light fitting not insulated and it contacted the light frame and blew the fuse..