is 240v really that dangerous

[Mikefromlondon]

I know a guy who died from a 12v car battery, he took the battery out as it was covered in white deposit after acid had been leaking from an overcharge, so he took it to kitchen sink, and washed it all out nice and clean, then as he was carrying it back, he started to feel tingling through a small cut in his fingers, and the tingling started to get worst and worst, until he could not bear it anymore, so he dropped the battery from waste height and it landed on his bare foot, crushing it badly, 2 months later he died of gangrene.

And I think even 1.5v could kill you if you swallow it, including a button cell.

and as for my personal experience, whenever I come in contact with any exposed electrical parts, my natural reaction is violent, so if I had a screw driver in my hand it would go flying, and once I reacted so bad that I hit my elbow against a sharp corner and the pain from that cut was unbearable!

People fail to realise, that our body works on tiny signal voltages and if a large amount of current flows through our nerves, they will swamp these tiny control signals and even if you wanted to let go, the weaker signal will be overpowered by the stronger currents and not let go instead do the opposite, so if you were holding something that was electrocuting you, you will end up holding it even tighter! and slowly get roasted inside.

A woman once asked me to change her two round tube light fittings to normal standard pendulum lights, in her dining room/kitchen (a long room half used as dining and half as kitchen) and there were two switches one for each light, so i assumed both were on one circuit, so as she went in her cellar to switch each MCB off one by one until the light that was on went off, I shouted stop! as we only had one light on, so when it went off I took it that both lights are fed by the same MCB and so both must be dead now, so after wiring then first pendulum, I reached for the second one to work on some idiot had wired that to another MCB. I was ok only that the sparks went flying everywhere. Why do you think professional Electricians are called sparks, the woman went hysterical! are you Ok, are you Ok, and I replied no i am dead, and I am talking to you from hell!

End of the day I tell people that Energy can create, Energy can Destroy, Energy is just a tool that can do lots of things.

 

[stillp]

I've heard of several such cases over the years, in which the heart appears, superficially, to recover normal rhythm but the current has had some deeper phsysiological effect which causes it to go into severe arhythmia or fibrillation hours later. I understand that at least in some instances an ECG carried out after a shock which has affected the heart can show the warning signs, even if the person feels fine.

It can happen, although is pretty rare. Only a massive shock, which would probably kill immediately, would be able to do any physical damage to the heart. However, what can, and sometimes does, happen is that the initial shock may trigger a 'minor' (and asymptomatic) arrhythmia, which persists, and then after a day or four 'transforms' into to a lethal one (like ventricular fibrillation) - all that being far more common in someone whose heart was not in perfect condition to start with. In such cases, as you say, an ECG performed during that 'latent period' would show the 'minor arrhythmia', which might be able to be treated or terminated before it had a chance to transform into something nastier, and possibly lethal.

However, as I said, it's very rare (let's face it, the total number of UK deaths attributed to electric shock per year is not that far into double figures!) and, given that heart attacks and sudden cardiac deaths are very common, particularly in some age groups, at least some of the reports of deaths occurring a few days after an electric shock are probably pure co-incidence.

Kind Regards, John

OTOH, could some of the deaths attributed to heart attacks have been a delayed result of an electric shock?

 

[PBC_1966]

he started to feel tingling through a small cut in his fingers,

It's my understanding that it's the outer layers of skin which form by far the highest proportion of the body's resistance which limits the current flow. Once the outer layer has been penetrated, the tissues below are a surprisingly low resistance even from one end of the body to the other.

Obviously with electrodes securely attached with the intent of ensuring a good connection, but readings reported from use of the electric chair indicate that after the initial high-voltage jolt has broken down the resistance of the outer skin layers the current which flows indicates a body resistance in most cases of only a few hundred ohms at most, sometimes well below 200 ohms, top of head to lower leg or ankle.

Much medical equipment is subject to very strict standards due to the way in which it can be used and that a tiny voltage - one so small as to be imperceptible with "normal" contact on the skin - applied internally could be quite dangerous.

 

[PBC_1966]

OTOH, could some of the deaths attributed to heart attacks have been a delayed result of an electric shock?

Quite possibly, given that in many cases the doctor attributing the cause was probably never even aware that the shock had occurred.

 

[mrstitt]

The HSE do a nice handbook on electrical safety - with case studies full of gory stories. I remember one example of a poor arc welder working in the Glasgow ship yards. He was wading up to his waist in water and using a 50v arc welder. needless to say he touched the end of his welder and his employer had to pay for a wooden box, few cars and a bunch of flowers.

I don't know if it was an urban myth or not, but someone I used to work with told me about a chap who worked in a gantree crane in a steelworks. The chap got out of his cab and needed to go to the gents - only the gents is a long way to go from a gantree - so he relived himself from the cab door. When your doing your business its helpful to have something to aim for, so he chose a bus bar that powered the crane motors. Urine is rich in salt so very conductive. Now imagine the entry burn....

 

[JohnW2]

OTOH, could some of the deaths attributed to heart attacks have been a delayed result of an electric shock?

Probably not deaths attributed to ('proven') 'heart attacks', since it is very difficult to see a mechanism whereby a prior electric shock could bring that about, but it's certainly possible in relation to deaths attributed to 'sudden cardiac death' (assumed to be mainly due to arrhythmias, in the absence of any evidence of a 'heart attack').

It would, however, probably be next-to-impossible to investigate that possibility, since reliable information as to whether the victim had suffered a 'minor' electric shock in the preceding days would only really be available from the person themselves, but they would not have come to medical attention until they were dead, hence not able to answer questions!

Kind Regards, John

 

[PBC_1966]

reliable information as to whether the victim had suffered a 'minor' electric shock in the preceding days would only really be available from the person themselves

Or possibly somebody else - If he even remembers it or thinks it relevant to mention since the deceased "Got over that minor shock days ago."

 

[eveares]

240v along with any voltage high enough (around 50V or above) has the potential to kill someone. What really matters is the amount of current that flows through someone and the path of this current flow.
A insulation resistance test applied at 500v but only 1ma is highly unlikely to be directly lethal where as 240v mains at tens of milli-amps can be lethal under the right conditions. Don't for get the Electric Chair uses 240V AC to execute people.

Additionally, an electric shock can damage and cause the hearts electrical systems to fail over several hours or even days, where one can die from an electric shock several days later.

I would seriously try to avoid getting electrical shocks from the mains, the next one just might kill you.

Hand-to-hand surely.

Or arm to arm - straight through the heart

And I thought we got some stupid questions in the Plumbing Forum but this OP should be a candidate for the Darwin awards!

Cruel but true...


And for ElectroBoom...Well his videos are just obviously stupid IMO, not good faking electric shocks or doing fake comedy.

 

[JohnW2]

reliable information as to whether the victim had suffered a 'minor' electric shock in the preceding days would only really be available from the person themselves

Or possibly somebody else - If he even remembers it or thinks it relevant to mention since the deceased "Got over that minor shock days ago."

Yes, but that's why I said 'reliable information'. Reliance on information from others would undoubtedly result in under-estimation of any association between sudden cardiac death and 'minor' electric shocks in the preceding days.

Kind Regards, John

 

[JohnW2]

he started to feel tingling through a small cut in his fingers,

It's my understanding that it's the outer layers of skin which form by far the highest proportion of the body's resistance which limits the current flow. Once the outer layer has been penetrated, the tissues below are a surprisingly low resistance even from one end of the body to the other.

That's true but, despite what you say, it's not all that surprising. Once one is below the outer dry 'horny' ('insulating') layer of the skin, the rest of the 'body tissues' are hardly 'tissues', since they consist primarily of mineral-rich water.

Kind Regards, John

 

[PBC_1966]

Don't for get the Electric Chair uses 240V AC to execute people.

The initial application is always much higher than that - I think the lowest I've seen quoted is around 1500 to 1600V, the highest about 2400V. In some systems the voltage is stepped back after a few seconds, sometimes to around 500 or 600V, sometimes as low as 240 or even 208V.

Yes, but that's why I said 'reliable information'. Reliance on information from others would undoubtedly result in under-estimation of any association between sudden cardiac death and 'minor' electric shocks in the preceding days.

Certainly - It would mean that other person remembering the incident, associating it with the later death, mentioning it to the doctor, and the doctor correctly attributing it as the primary cause and not dismissing it as unrelated. So as you say, under-estimation would be just about certain.

 

[JohnW2]

Certainly - It would mean that other person remembering the incident, associating it with the later death, mentioning it to the doctor, and the doctor correctly attributing it as the primary cause and not dismissing it as unrelated. So as you say, under-estimation would be just about certain.

If one were actually undertaking a survey, one would not have to rely on others spontaneously remembering or mentioning it to the doctor, and nor would there being any risk of the doctor not recognising a possible association - since the families would be directly questioned about the matter by people who knew why they wanted the information.

The greatest risk is that the people asked simply wouldn't know - I would suspect that a lot of electricians and other tradespeople etc. who suffered seemingly minor electric shocks would not mention it to their spouse - either "just because they didn't" or possibly because they did not want to 'worry' the spouse. Perhaps because age brings a degree of wisdom and sanity, it's very many years since I last suffered an even remotely significant electrical shock - but in my more foolhardy days as a teenager, I'm quite sure that I never told my parents if I had (done something silly and) suffered a shock - and the same was undoubtedly also true (in terms of my wife) in the early stages of my marriage! So, had I dropped dead a few days after any of those incidents, no-one alive would have known.

Kind Regards, John

 

[eveares]

The initial application is always much higher than that - I think the lowest I've seen quoted is around 1500 to 1600V, the highest about 2400V. In some systems the voltage is stepped back after a few seconds, sometimes to around 500 or 600V, sometimes as low as 240 or even 208V.

I do wonder if the poor person getting executed is rendered unconscious immediately?

 

[PBC_1966]

If one were actually undertaking a survey, one would not have to rely on others spontaneously remembering or mentioning it to the doctor, and nor would there being any risk of the doctor not recognising a possible association - since the families would be directly questioned about the matter by people who knew why they wanted the information.

Ah, a specific survey would be a little different; I was thinking before of simply collecting the information in the normal course of events. But as you say, the other factors at play would have a huge effect anyway.

I do wonder if the poor person getting executed is rendered unconscious immediately?

I believe that's the reason for the use of the higher voltage (at least on initial application), the theory being that it causes enough current flow to destroy brain function and render the condemned unconscious almost instantly. The rest of the application, sometimes at lower voltage & current after a few seconds, is then kept applied for longer to ensure complete destruction of autonomic functions.

 

[JohnD]

I do wonder if the poor person getting executed is rendered unconscious immediately?

No, I understand they die by suffocation as the chest is unable to breathe.

They are hooded so that the people watching do not have to see the horrible death throes. For some reason US executions sometimes have groups of spectators.