Many have had a 'belt' from domestic 240Volt wiring through bad luck, bad judgment or plain stupidity . Whilst a shock from 240V CAN kill how often does that actually happen and how many just get thrown across the room into a foetal position whimpering and crying until the arm unknots and the tingling feeling goes away.
I was sitting on a quarry tiled kitchen floor connecting up a cooker. My understanding was the the supply was isolated, that quickly got revised when I tried to strip off the insulation of a live 10mm2 feed with uninsulated side cutters.
Well the key is where you take the shock. It only takes a surprisingly small current across the chest to kill you merely by stopping your heart, that is why the one hand in your pocket advice is so useful. Lots of us have had shocks, mine were usually thru the fingers of the same hand when delving inside a working piece of valve gear that had series fed heaters across the mains. Yes you get some expletives but not much else. The buzzing bruised feeling soon passes.
Remember in the past some dodgy practitioners thought shocks were actually therapeutic, How they did not manage to kill most of their patients is amazing. I'm also sure as kids we all made electric shock machines All you needed was a small mains transformer a battery and something like a mechanical buzzer. You wired the buzzer and secondary in series with the battery and a switch, and asked your victim to hold the ends of the primary. I guess current was quite low, but when bridge rectifiers and small high voltage capacitors came along you could end up with something really dangerous. What we used to do was charge up a capacitor and leave it on a young ladies seat and watch what happened when she picked it up, Ahem, Well it was fun at the time... Brian
The radio room at Lyons where I did my apprenticeship had two door handles that had to be operated simultaneously to gain entry.
Been there done that - once! When I was about 8 years old I had a crystal set and thought I needed a longer aerial on it to get better reception. Had seen pylons with wires on them supplying electricity so thought that would be a lovely aerial!. Went to mains socket in bedroom with metal meccano screwdiver in one hand, bare wire to plug into socket in other. Pushed down the earth shutter with screwdriver and inserted bare wire into now open shuttered pin. I now know the difference between live and neutral! Seriously thought I was going to die. Been extreemly cautious ever since and never had another belt from the mains!
I looked into this a few years ago when I drew the short straw and had to conduct some staff training about electrical safety.
Very approximately, 30 people per year die in the UK from electric shock. Nearly all of those are from digging up cables or contacting overhead cables. In other words, very few from the domestic mains.
Figures for the number of indirect deaths - eg falling off the ladder due to a shock - were not available, or at least not easily, and I didn't care that much anyway. The small, innovative company had just been bought by GE and I wasn't hanging about to be tapped in a world of online training courses and wearing Kevlar gloves to use a scalpel.
Well didn't an MPs daughter die of a 240V shock in a domestic incident ?
And Keith Relf formerly of the Yardbirds was killed in an electrocution at his home (so presumably 240V).
When I was at Uni a lecturer mentioned checking out a neighbours cooker that was "buzzy" when you touched it. He found there was no earth and
600V potential between it and the sink ...
I had a not dissimilar experience. I'd been given a mains radio, one where the DC was obtained simply by directly rectifying the incoming mains with no isolation, i.e. chassis connected to neutral etc. Unbeknown to me, the previous owner had managed to reverse the live and neutral wires in the plug, which meant the chassis was always live. I was aware from crystal set experience that an 'earth' was a 'good thing', so I attached a wire to the chassis and dangled it out of the bedroom window. Downstairs and outside, the plan was to attach it to the rising water main. But I couldn't quite reach the dangling wire without stretching up with one hand and holding onto said rising main with the other hand for support. OUCH! I suppose I was lucky, because that was the classic situation for electrocution, from one hand to the other right across the heart. Being off-balance at the time did mean immediate disconnection as I dropped down, which probably saved me.
I doubt anyone has statistics on the latter - and I'd doubt their reliability if they require people to own up to the whimpering bit :)
But deaths are few. Used to run at about 15 a year in England where the /underlying/ cause of death was electric current. And bulk of those were not in the home (and so include ones where more than 240v involved).
There are of course serious injuries on top of the deaths. But changes to BS 7671 seem to be made without assessments of costs and benefits. Too much flavour of "no price is too high..." for my liking.
soup explained :
I've had many shocks, it usually doesn't much bother me, except for once when I genuiningly was thrown across a room, a flooded banking hall.
I was the key holder. It was raining heavily, I was wet through as I walked in, alone. Carpet soaked, several feet of water in the basement, water dripping from the ceiling, several dehumidifier and fans in use, for safety all individually powered via RCD's - all set up by me. I had written a large notice, which I placed at the RCD's, saying everything had to be powered via an RCD - no exceptions.
Unknown to me, an unskilled trainee had been there the previous day and one of the dehumidifier (industrial sized, metal cased) was tripping its RCD, the stupid bugger wrongly assumed the RCD was at fault, ignored the notice and bypassed it. The dehumidifier casing was actually live, putting everyone at risk who went in the banking hall.
The company denied any responsibility, refused to investigate, basically called me a liar. I had gone in alone, there were no witnesses, luckily I only had a few bruises - so easy for them to deny it happened.
You can do your best to make things fool proof, but somebody is bound to invent an even bigger fool.
Brian Gaff (Sofa) laid this down on his screen :
Across the chest is the worst possible type of shock, almost as bad is from the hand and down through the body to the wet feet.
They do still use a type of electric shock machine. They sometimes call them 'TENS' commonly available with a type sold on TV ads. (Think cricketer). Idea is the controlled electric shocks, trigger local muscles, which also helps stimulate circulation and maybe use up fat in the body.
I think that is on the low frequency setting (around 3 Hz, but variable on many) - pulses that cause the muscles to contract. On the high frequency setting (150Hz), the muscles don't have time to react, but the nerves become numbed, relieving pain.
Electrocution isn't always a dodgy therapy. The NHS still use electroconvulsive therapy (ECT) for severe depression if there's no other practicable option.
OK, you've got my curiosity --- how do you get a 600 V difference inside one house?
Which is almost impossible to avoid in cars ... one hand on the chassis, the other poking around near the HT leads ...
As a very young child I got a nasty jolt from putting my fingers in a lamp bayonet socket. I didn't do that again! But the worst shock was when, as a young teenager into hobby electronics, I was making a small valve-based transmitter. I was holding the HV DC +ve lead (about 350V) and went to move the large smoothing electrolytic the -ve was soldered to. I didn't know that the -ve and metal case were often connected. My hand clamped around the electro so that I could not release it, but very fortunately my biceps muscle also contracted and I involuntarily threw the electro across the room, thus breaking the connection. It was one hell of a shock, and I was very lucky the connection had been broken.
Adam Funk pretended :
+1
Ah, but was the sink earthed? ;-)
PA
I'm more careful generally as I age
Or your skin impedance is rising... ;-)
PA
I have no idea exactly. We were discussing "earths" and the fact that your earth and my earth may not be the same. Isn't that why there's earth bonding everywhere ?
It was thanks to this lecturer that I always factor a sudden loss of power and services into a building that can last a day into my BCP/DR planning. "Murphy and his jackhammer" were a recurring theme ...
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