[Closed] Will 240V kill you?

will 240v kill you?

I have had a few 240V kicks while trying to work out the electrics in our house

to conclude, no.

as for "[i]could[/i] 240v kill someone?", yes.

[url= http://en.wikipedia.org/wiki/Electric_shock ]Write a will[/url]

It depends on the current at that level doesnt it? Very high voltage such as power lines will def kill you but 240V wont dependent upon the current but I wouldnt take any risks!

It has the potential to.

Get an RCCB fitted quick.

"Get an RCCB fitted quick."

or turn the 'leccy off before rewiring the house?

BigJohn - What's one of them then? We have a box under the stairs with a load of trip switches in it. Normally these trip automatically when I put my finger on the end of the wire to stop it flowing out but I have had a couple of 2-3 second blasts where I couldn't move out the way*.

*Upstairs bathroom extractor fan wired into downstairs light ring.

Fuse box labelling is great. I just wish it reflected what the fuses actually did.

i connected myself up to the mains as a 12 -15 yr old (ish) while wiring up some mains christmas tree lights, and forgetting to unplug the bloody thing while taking the chocolate block apart at the "mains end" (it was a bodged set)

anyhoo!
that smarted somewhat, but im not dead.
worryingly perhaps, it didnt trip the RCCB nor did it blow the fuse in the plug.
i like to think if i had anymore than brushed the tip of the contact, it would have tripped, but im not going to find out.

i would imagine doing the same while in a bath of salt water would be less funny.

Given your previous WCA I'm slightly worried !!!

Burnt the end of my finger off when I was 3 by shoving it in a light fitting (now have no finger print on that finger).

A healthy adult would struggle to kill themselves with 240 mains.

Most sparkies work on live mains. I do most minor electrical jobs on live stuff - easier than resetting all the clocks etc.

I've worked in substations and they do everything live on the LV side of the transformers, you just stand on a rubber mat.

IIRC 50mA (approx) is required to kill you if it passes through your chest. Most of the time you'll struggle to get that from a 240v source due to the resistance of your skin/body, so most of the time it'll be a zap and nothing more. Wet hands, grip the wiring in each hand - probably fatal.

I've taken a momentary direct hit from right arm, up through chest to top lip (dont ask!) from 15kV - hurt like hell, left me sat several feet from the source unable to recall the last few seconds, but I'm still here. I think it effectively just rebooted my head lol.

Don't know much about the effects of electricity on the body other than personal experience: 9v batteries are interesting if you put them on your tongue, and household mains is suprising but not deadly.

I do remember this from physics at school "Volts jolt, Amps kill" Goes with what robbo said about "dependant on the current". bun

Your heartbeat is controlled by tiny electrical signals from your brain, wacking 100's of times that amount of voltage through your system causes the muscles to spasm, the fact that you're still alive shows that they've managed to recover - sometimes they don't!
An RCD measures the current flowing in through the live & out through the neutral in a circuit, if any 'leaks' then there will be a measurable difference & this is used to trip the device. Most leakage will be through damp or someone getting a shock.
If in doubt isolate it - its not worth risking your life over.

It is indeed current that kills, but generally you need a high voltage to get that current, so it's a tad misleading.

I have to say, WCA is my favourite thread author for practically any DIY related subject.

My sister's friend topped herself by immersing a toaster in a salty bath with her. Not nice, but it did make me wonder why the fuse wouldn't have tripped and saved her?

No wonder you are called WCA. can you not get a tester to check the wires are dead before you start a job?

It comes down to V=I*R but yes 240 "could" kill you. the only voltage considers safe is 50v(ac) or bellow which is know as SELV (Seperate Extra Low Voltage).
With AC you will normally get through away from it/let go of what is giving you the shock with DC (ie batteries above 120v) will leave you holding on to what has shocked you.

Ohm's Law:

V=IR

Current=Voltage/Resistance

-So the current is proportional to the voltage and inversely proportional to the resistance (of your conducting body parts).

A 'small' power supply may not provide sufficient current to cause you damage.

As I was told during trade training 'Any voltage is dangerous'. Make sure you work with one hand in your pocket, stood on a big bit of rubber with a saftey man.

IIRC 50mA (approx) is required to kill you if it passes through your chest.

The way that info was gained is not a nice thing either.

I learned about this watching a film called "Running Scared". They were driving a police car down a train line and one said to the other to avoid the middle rail as it was at 6000V, to which the other replies, "it's not the volts that kill you, it's the amps"

The nun in the back chips in with "oh, how many amps are there then?"

to which he replies "enough to push a ****ing train".

Sorry, guess you had to be there.

Wet your hands, grab a water pipe with one and then touch the live wire with the other - that'll probably kill you*.
The only reason the others haven't is high resistance to ground, not allowing much current to flow.

* please don't.

Shaking hands with the National Grid is not considered a good thing OK

The only reason the others haven't is high resistance to ground

Are you saying theres a lot of WCA between the wire and ground?

these trip automatically when I put my finger on the end of the wire to stop it flowing out

That's your problem. You should just be catching all the electricity in a bucket (with a rubber handle) and then pouring it back into your meter when your done.

Buy a voltmeter for god's sake! A somewhat better way of checking if something is live! 😯

Even one of the current-detecting screwdrivers would be a good idea.

WCA, I do electrics at home. But if you don't know how to isolate (turn off), have insulated tools, or how to test for live current, or understand what an RCCB is you should really leave it alone. You may not hurt yourself, but you may hurt someone else.

Neighbours house caught fire, because some DIY nerd fitted lighting flex for a 13amp socket! They were out for 1 year, while the inside and roof of there house was rebuilt.

Be careful WipeOut

Used to work in a factory making electric motors. One of the jobs involved taking finished motors off the line, placing stripped wire ends into the sockets and test running them. Used to get the odd faulty one with a live case, touched bare wire ends whilst switched on etc (testing 15 at a time and keeping up with the line these things happen even when you're careful) . Those shocks were never that bad, it was the capacitor wires dangling all over the place that really hurt. Always made sure i wasn't desperate for the loo on that job!

Not nice, but it did make me wonder why the fuse wouldn't have tripped and saved her?

Fuses are not really there to protect people, they never have been and are not designed for that - they just about protect the house wiring and to some extent the appliance wiring from catching fire in the event of a catastrophic failure. They're a slow-blow device which can take seconds to blow if they're only just over their limit. This is why RCDs were invented, they're near-instantaneous and ARE designed to protect people.

coffeeking - I assume the RCDs are the little trippy switches in what I used to call a fuse box. I have had the 240V tingle a couple of times without tripping stuff.

For the rest of you, I do normally turn the electrics off in the house before touching anything. The times I have been caught out are when things are madly wired as in my last two examples.

I must plead stupid to my last shock. It was dark and had to rewired downstair hall light switch. Turned of downstair lights and used the helmet lights to see what I was doing. Got the tell tale tingle and remembered that the switch I was working on did the downstairs AND upstairs hall lights.

YES it can kill. Instantly.

But as mentioned it does depend on the load on the live wire / surface touched, humidity, skin moisture, what stands between you and ground etc. etc..

I've got away with 240V twice. It's bloody awful and for a few minutes afterwards I still thought I might expire. Respect electricity and concentrate at all times. Label things clearly or lock them out. Just be bloody careful.

Thought its the Amps that do the damage.

Maybe you only touched the the positive end and had a minor shock.

Jeebers WCA be careful (nutter) 😉

As a young lad I pee'd on a fence, it was electric, I got a hell of a shock through ma willy. Been trying to recreate that feeling for the last 40 years!

Just found out they have Defibrilaters in the coffee rooms here...

... now what could I do with one of those?

Would defibing a work colleagues backside kill him or just be funny?

If it's an AED (probably) it won't do anything.

They only shock if they can find a shockable heart rhythm and to do that the pads need to be on the right place.

"As a young lad I pee'd on a fence, it was electric, I got a hell of a shock through ma willy. Been trying to recreate that feeling for the last 40 years!"

www.pes.com

UncleFred - What are the chances of that link being worksafe?

coffeeking - I assume the RCDs are the little trippy switches in what I used to call a fuse box. I have had the 240V tingle a couple of times without tripping stuff.

Yup, but not all places have RCDs. My rented flat only has it on some consumer-facing circuits!

Thought its the Amps that do the damage.

See above, yup 🙂

derek_starship

Yup, but generally if you know what you're doing and limit the risks it's not so bad - I know of a couple of people who worked with 200A supplies day in day out (industrial usage) who used a brush with the backs of their hands to test for live, dozens of times a day. I'd not advise people to try it though!

I was getting one of the smoke alarms (mains powered ones) down to replace the back up battery, I was only "fairly sure" the alarm was isolated and couldn't really see what I was doing but was aware of exposed electrics inside.

It was the kitchen one and my wife accidentally knocked over the 5kg solid oak chopping board that was leaning against the back wall on the work top. The ensuing bang as I removed the device caused me to, without a doubt, come the closest I've ever come to literally shitting myself.

Just thought I'd share 🙂

back when i was a small boy i thought how much faster would my train set go if i removed the 12v transformer and just wired the track straight to the mains. so using a pair of nail clippers i cut the wire off the transformer (while still pluged in) that went fine, striped off the insulation , then i grasped the live wire and thats when it all went wrong, several seconds of bouncing around around unable to let go of the wire followed by dad running in and pulling me free shocking himself in the process. so in answer to your question does 240v kill nah 😀

1) Yes 240V can kill - I've lost colleagues to it - but not always.
2) The lowest voltage that has been documented (according to the initial safety training at the electrical distribution company I work for - about 17 years ago) to electrocute someone was a torch battery at about 20 volts or so - but they were in an odd evironment at the time (cleaning a mash tun if I recall)
3) National Grid don't supply 240 volts - they tend to stick to 275kV or 400kV with connections to distribution companies at 132kV, 33kV or 66kV.
4) You might get away with playing with the 240V system - plenty do - but then again you might not.

This is sounding a bit more serious than I thought. I have lost count of the number of times I have had 240V shock over the years.

We used to use it as a bravery test to be in my gang at primary school and I once tried to cauterise a cut using the flex from a lamp with the lamp cut off and the two wires held close togetehr over the cut. I should point out that I was a little pissed at the time and had just knocked over and smashed my mums glass lamp.

WCA - You personally will get away with it because Karma's purpose for you is to allow you to do dangerous, amusingly almost catastrophic, or down right stupid things and then get you to write them up on here for the enjoyment of us mere mortals who would be killed by your exploits. 😉
I know this because I've see a) your user name (there's a clue there) and b) some of your previous posts.

You'll probably get away with playing with 240V most of the time - but not all of it, and you never know which time it is that you've just got something a bit different and you pay for it. I wouldn't recommend it.

There have also been a number of instances where people got across the 33kV or 66kV and survived - not necessarily intact or fully functional, but alive. I definitely wouldn't recommend that.

Don't play with electricity, boys and girls. It's not big or clever and it can be a bit upsetting clearing the mess up afterwards - not that I do that in my nice safe office job.

even small voltages can kill as they can throw your heart out of sink, 240 even in small bursts will kill some people

One of my colleagues knows someone who is partly paralysed down one side. His dad had the cover off the washing machine to work on it when he was a kid. He picked up a screwdriver and poked it into the machine when his dad left the room to get another tool and received a shock.

240v killed my mate Chris 🙁

He'd fixed his girlfriend's washing machine, plugged it in to check, all good, realised he'd left screwdriver in the machine reached in to get it. 🙁

WorldClassAccident - Member

UncleFred - What are the chances of that link being worksafe?

Perfectly safe for work, if you work in a "Private Shop"

Mmm, so 240v [i]can[/i] kill you... Is there any way of [i]guaranteeing[/i] it will kill you?

50mA will kill you. 30mA might well do so.

As others have said - its all down to the current (amps). Dry skin is an alright (I use the term loosely) insulator - plenty of resistance, so not much current flow (assuming you're acting as an earth path). You'll probably get away with it. Probably.

Wet or sweaty skin (nerves from working on live electrics maybe?) has a low resistance, so you get a lot of current flow. Bang, you're dead.

If you manage to connect yourself in series with another electric load that's drawing current - you're definitely dead.

A fuse or an MCB protects against overcurrent. If you have a 13A fuse in your plug, by the time it blows, you'll probably be dead (remember 50mA = 0.05A). An RCD measures the difference in current in the live and neutral cores. If they differ by more than the "trip" value, they trip.

I've had a few shocks in my time (I work as a lighting technician). I've had yet more near misses. I could happily live the rest of my life without any more of either

anyway, your very unlikely to come across a 240v supply in the UK, seeing as mains is 230. oh the joys of learning this stuff presently.

UK mains may now be 'officially' 230v, but due to the tolerance band, you'll still see 240v and more at the socket. I'm currently retraining to be a spark so keep up the bodging chaps. Incompetent DIY'ers should keep me in work for years if they can manage to stay alive long enough.

The flicky switches in your consumer unit are likely to be MCBs, not RCDs, so are designed to protect the wiring installation, not you. RCD protection is a relatively recent thing and many consumer units won't have any fitted. If you have RCD protection (either RCCB or RCBO devices - should say on the front) and they aren't tripping when you give yourself a pisser then you have a problem.

I really dont understand why people WHO HAVE NO IDEA ABOUT ELECTRICITY seem to think that it is ok to work with it. Its a seriously dangerous force. It isnt just your life you are putting at risk, but family and anyone who comes to your house. Why do you think that the electrical instalaton industry is so tightly regulated? I didnt do a 4 year apprenticeship for nothing.

230v can and often does kill. It can also cause fires and explosions. Its not worth the risk and i would say you have been lucky so far.

As said above 240V can and does kill, fact.

I have been told from a reliable source that 60V DC has the capacity to kill as well. Sparky pal of mine told me once that a 13A fuse by the time it blows could be passing 2 or 3 or 4 times that current, and you are fried by the time it does.

I also heard on a static electricity course that 1 joule of electricty in the wrong place on your heart can stop it, that is 1W for 1sec, which is a very small amount of electricity. Static from clothes for example is 1000's of V but very low current so its harmless. Static discharge from a large helicopter grounding however can kill you.

So dont be silly and get a sparky in 🙂

a 13A fuse by the time it blows could be passing 2 or 3 or 4 times that current, and you are fried by the time it does.

Your sparky friend is talking a mild amount of bollocks. You'd be fried without the fuse necessarily blowing at all. 50mA will kill you. That's 0.05A. 0.05A won't blow a 13A fuse.

Dudie - you are right that fuse may not blow, but he is not talking bollocks as you put it, a fuse will pass current a number of times higher than its nominal rating before it blows.

Quite correct. Not disputing that. The insinuation was that you would be fried because of the fuse not blowing at 13A. All I am saying is that you would be fried regardless - you would be dead long before the current got anywhere near level required to blow the fuse. Must dash, got to swot up on me live testing homework!

's fair enuf....

I saw a guy die at a gig. He was a guitarist and as they were tuning up he grabbed the mike stand, did a little shaky dance and fell over, dead.

Turns out he had got fed up with the fuse in the amp blowing so decided to use a paper clip instead.

ive seen peuple use cut down, then soldered on nails as 'fuses' on a lighting circuit 😯

cullen-bay - Member
anyway, your very unlikely to come across a 240v supply in the UK, seeing as mains is 230. oh the joys of learning this stuff presently.

I like that one.

Sorry to do this but when the statutory mains voltage at LV single phase changed from 240V +/-6% to 230V +10%/-6%, what do you think the electricity companies did? Go out and change the voltage at every substation (easier at the primaries but still a git)? Or work out that 240v +6% and 230V +10% are virtually identical and leave well alone? Could it even be that this is why the tolerance band chosen is the one it is? You got it.

And by the way we design to be as close to the upper limit as possible at no load, so that as the load comes on and the voltage drops we have as much room to play with as possible. Saves on copper / aluminium and means you the great British public pay slightly less distribution charges on your electricity bills.

WCA...that downstairs light, try the same trick again but touching an earthed bit of plumbing...you'll get a much bigger bang! This is why its no longer normal practise to earth the kitchen sink as its quite likely you will drop a kettle or electric whisk into the water...the shock will be less severe if the sink is unearthed. Also why plumbing and elecrics are earthed together in bathrooms, so everything is at the same potential. A big plus point for push fit plastic plumbing 🙂

Yeah, yeah, yeah, all very interesting stuff: real men talking about really manly 'lectric and all that but no one's actually told me how to guarantee death using the 230/240/250/whatever volts that my house has got.

Does dropping a toaster into a bath really work [b]one hundred percent[/b] of the time???

Cut the skin on one thigh and the opposite shoulder. Apply phase to one and neutral to the other, both into the cuts.

Please do not do this.

No no no, that sounds painful! I'm looking for a quick 'n' easy way out that can be done at home with minimal preparation. Does electrocution involve lots of pain and thrashing about? Or is it pretty instant?

Thanks for your input though! 🙂

I zapped myself with the mains once whilst working live. I struggled to pull my hand off the wire and the flow went right through my chest ,weird feeling when it hits your heart .

My arm took days to go back to normal what with all the tingling

I've known people killed not just by the 240vac, but the stuff they've fallen on to. Ffs people, be careful.

yeah, i was working at a site, and another electrician (honest) f'ed up. result was a coms engineer grabbed hold of a piece of metal conduit at 230v, 32 amps (yes the amps are the really dangerous part). He was on load of metal racking. Result was he was thrown about 12 foot onto the concrete below. Luckily he was just bruised and shaken. His mate started on me, thought he was going to go for me but some other people calmed him down. Lets just sy it was not a good experience for anyone. Does no one remember that incident with the mp's daughter who died frm a shock in the kitchen. That was more or less what sparked off this whole 17th edition thing i think.

People say amps kill because of the I squared R losses as the current goes through your body, but there are other ways to die.

If your lucky a few milliamps (50 has been quoted on here and I'm not going to argue with that) interfere with your nervous system - heart attack - dead. That's really the voltage signal, which maps onto your natural electrical system fairly well, killing you.
Next up the shock causes trips and falls - and the fall kills you.
A weird classic is the man who jumps on to an overhead line and grabs one of the conductors - but he isn't making a circuit, possibly even the instantaneous protection that they have on that kind of circuit kills the volts, so he just hangs there until his strength gives out and he falls with predictable consequences. Possibly apocryphal that one.
Getting into the nasty ones, the current cooks your flesh - ever seen a bit of meat that's been in the microwave too long? - and you die.
Worse maybe you survive initially but the shock from the burns kills you within a day or two.
But that's better than the cooked flesh slowly going off inside you with the accompanying blood poisoning.
Of course that doesn't consider the various problems caused by electrical flash or fire.

If there are any doctors out there they may wish to correct me on the details.

For everyone else I think it may be time to close this thread.

Don't play with it if you don't know what you're doing - and if you do know what you're doing, play carefully.

240v killed my mate Chris

He'd fixed his girlfriend's washing machine, plugged it in to check, all good, realised he'd left screwdriver in the machine reached in to get it.

Wasn't down Sussex/Kent way recently was it? There was this exact tale in our local paper not so long ago - someone killed whilst repairing a washing machine.

Any changing of plug sockets / light switches / light roses etc in the house I make sure the power is off at the mains. Not worth the risk IMO...

Someone said "Volts jolt, amps kill". This is very confusing and can give out the wrong message that any voltage is safe if the amps are low. The fact is, it only takes a tiny amperage to kill you. The reason we don't all die when we touch a battery is because it takes a lot of volts to pass though your heart.

Unfortunately, what they teach in schools up to secondary level is wrong. They can't seem to explain the difference between volts and amps and this was one of the first things our lecturer at college put is straight on. Years later, I had an argument and lost a friend over this one evening. She was being paid to mark science exam papers, incorrectly! No wonder people get confused, hate Physics and that this country has so few people wanting to be engineers!

I'll explain why high voltage kills, not high amps: Put simply, you need high voltage to "jump" through you. The higher the voltage the easier this becomes. A deadly shock attacks the heart and the most effective way is to allow current to pass through your rib cage. To minimise this, people having to work on live high voltage equipment will often stand on rubber mats/wear rubber boots (to prevent a route to earth through their feet) and always have one hand only on the equipment.

Alternating current (AC) is used for transmission of power as it looses less energy than DC. In order to efficiently transmit power over distance, we use AC high voltage and low current. That's why power lines suspended across the countryside are at very high voltages. If we used DC and low voltages, the lines would need to be incredibly thick to handle the current, but we'd still loose a lot of power. e.g, double the voltage, halve the current. If you've ever installed a powerful car ausio system, you will have found that the power cable on offer is very thick. It needs to be to handle the current demand of a system powered by just 12-16v.

Back to living creatures... It only takes a few millamps to kill you (I believe the figure to be 1.6 Milliamps or 0.0016 amps ) - it will cause your heart rhythm to be interrupted and if you don't survive, it will be because you've had an heart attack.

Conversely, holding the terminals of a low voltage, high current source, such as a 50Ah car battery, will not even register the slightest tingle and is completely safe.

I can't remember exactly what a safe voltage is, but it's something like 50v, or maybe a bit less. 50v [i]will[/i] give you a nip and it really does depend on moisture (a conductant). Sweat is a good conductor, perhaps due to the salt content. If your skin is bone dry, you are less likely to get a circuit through you.

Conductivity is a big factor in whether you get a shock or not and how bad the shock is. If you are soaking wet, expect a big one. If your dry, you might not even get a shock.

However, if you introduce high voltage and high current over a period of time, you will fry - nasty.

Just don't fxxk with high voltages. Turn the juice OFF, but if this is not posible, proceed with extreme caution (like when diagnosing electonic equipment faults). Better still, get a man who is qualified to deal with it.

I like the quote somebody else made

I think it effectively just rebooted my head lol.

Alternating current (AC) is used for transmission of power as it looses less energy than DC.

AC is easier to convert to high voltage and back than DC - just use a couple of copper coils around a steel core, or transformer to the rest of us.

Also building AC circuit breakers is a sight simpler as you have some zero crossing point where arc extinction is easier.

It is the high voltage and low current that is more efficient as the I squared R losses are lower for any given power, not whether it's AC or DC.

However the next generation of power transmission (and indeed some that already exists - cross channel link anyone) will probably be DC for a number of reasons including ease of insulation and the decoupling of AC systems which can improve stability in large networks - not a problem in the UK as were too small, but in the States or if they ever build the Afro-European supergrid they're talking about.

But that probably won't run at 240V.

I'll explain why high voltage kills, not high amps

We run perfectly safe electric fences round some of our substations - 50,000V I seem to remember (Power fence are one manufacturer - google 'em). But limited to 5 joules (so not enough power to cook you) and not 50Hz so it doesn't mess your nervous system up.

So it's not as simple as Amps kill or Volts kill - it's a combination (they are intrinsically related after all), but frequency also comes into it and it depends on how you want to die. Please don't though.

The rest of what you said I'd not disagree with (except that 240 V is referred to in the industry as Low Voltage).