Reply to: Electrocution: Are there any PSU's that provide mains voltage to a computer?

[KentPhilip]

It is unlikely that a PSU will chuck out 240v because the voltage in the UK is 230v

No it isn't it's 240 volts:

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[doodab]

I'm not saying this is a good thing, I'm just pointing out that 99.99% (according to the statistics, i.e. 2.5 million shocks and 30 deaths) nothing much happens.

Except those stats are the same ones that gave us 300,000 serious injuries from 2.5 million shocks. So you can't really discount the 300,000 unless you also conclude that most of those 2.5 million shocks weren't mains voltage.

when I used to build power switchgear I worked with a guy who took 240V to ground via his arm after leaning on a bus bar thinking something was switched off when it wasn't, he had some pretty serious burns.

Oddly noone wanted to work on site with him.

[d000hg]

Well I grabbed hold of a wire the last time I had an electric shock, and it didn't throw me across the room. It was just rather painful. No burn just a shock. I think you are thinking of KV electric shocks.

I'm thinking what me dad told me, from his decades of DIY. I don't have any first-hand evidence and if you're equally experienced then maybe he was just unlucky.

[KentPhilip]

or those with a dodgy ticker.

get an RCCB. its worth it for peace of mind. have extra plug in ones for external tools the further you are from the earth the less sensitive they are.

An RCCB - residual-current circuit breaker.
If you electrocute yourself with one of those in circuit does it mean you'll only feel a tickle?

[vetran]

Well I grabbed hold of a wire the last time I had an electric shock, and it didn't throw me across the room. It was just rather painful. No burn just a shock. I think you are thinking of KV electric shocks. In fact some kids grab hold of main live wires as a dare. I'm not saying this is a good thing, I'm just pointing out that 99.99% (according to the statistics, i.e. 2.5 million shocks and 30 deaths) nothing much happens.

I suspect most of the injuries are caused by children sticking wires in their mouths or electric shocks in the bath, which are dangerous.

I'm just saying you would very unlucky,

or those with a dodgy ticker.

get an RCCB. its worth it for peace of mind. have extra plug in ones for external tools the further you are from the earth the less sensitive they are.

[BlasterBates]

Brushing a wire maybe. But grab hold of something, that's pretty bad news! At best you'll get thrown across the room.

This is assuming you don't have a proper circuit breaker... with those it should be safe to grab a live wire and IIRC my father tells me salesmen used to do just that when the modern ones were cutting-edge.

Well I grabbed hold of a wire the last time I had an electric shock, and it didn't throw me across the room. It was just rather painful. No burn just a shock. I think you are thinking of KV electric shocks. In fact some kids grab hold of main live wires as a dare. I'm not saying this is a good thing, I'm just pointing out that 99.99% (according to the statistics, i.e. 2.5 million shocks and 30 deaths) nothing much happens.

I suspect most of the injuries are caused by children sticking wires in their mouths or electric shocks in the bath, which are dangerous.

I'm just saying you would very unlucky, if you were to use your voltmeter and you accidentally tried to unscrew a live connection (which is basically how I got the electric shocks when I was doing my project at Uni).

[Paddy]

Pre circuit breaker days I forgot to isolate the electric shower before changing a valve. Left hand touched the pipe and right hand on the live. It did not throw me but it jerked my arms violently. It cured my reoccurring shoulder pain.

[d000hg]

Brushing a wire maybe. But grab hold of something, that's pretty bad news! At best you'll get thrown across the room.

This is assuming you don't have a proper circuit breaker... with those it should be safe to grab a live wire and IIRC my father tells me salesmen used to do just that when the modern ones were cutting-edge.

[BlasterBates]

You didn't say the risk of a shock was low. You said 240V wasn't very dangerous. So the comparison is not between using a chainsaw or changing a socket. It's between using a chainsaw or touching a live wire.

I'd rather grab a chainsaw than the mains.

If you have an accident using a chainsaw it's almost certainly going to be a lot more painful and nasty than if you touch a mains live wire.

I'm not saying it isn't dangerous, what I'm saying is it is unlikely you'll come to any harm, if something untoward did happen. For every 2.5 million schocks 30 people die, and having had quite a few electric shocks myself from the mains I can testify to the fact that if it does happen, you'll probably be perfectly OK, which is more than I can say for slipping with the kitchen knife.

The comparison is not touching a live mains wire and using a chain saw. The comparison is using a chain saw and using a voltmeter on an electronic device. A voltmeter has plastic leads so even if you did touch something that you shouldn't it would be the voltmeter that would cop it. In fact the fuse would blow.

So is it dangerous to touch a mains lead ? ...well you'd be unlucky other than to have a bit of a shock. Is it dangerous to use your voltmeter on some electronics?....no

[ctdctd]

I'd rather grab a chainsaw than the mains.

More fool you then - IMO

[d000hg]

Yeah which is the point I was making.

I mean drving down the motorway, taking your chain saw to a tree trunk, eating a can of beans (Botchelism) and having a hot shower (Legoinaires) all carry risks that we need to weigh up.

In comparison to most of the above using a voltmeter to check your PSU is pretty far down the list.

You didn't say the risk of a shock was low. You said 240V wasn't very dangerous. So the comparison is not between using a chainsaw or changing a socket. It's between using a chainsaw or touching a live wire.

I'd rather grab a chainsaw than the mains.

[vetran]

vetran, there is a lot wrong with your post.

it's not the voltage that kills you, it's the current. and the current has to be in the right place.

'less likely'

yes but to allow current flow through the heart from the extremities in most cases you need voltage.

but the link to wikipedia and the YMMV rider weren't enough.

[BlasterBates]

Lets put it this way grabbing hold of a hot soldering iron is more painful than an electric shock and the experience isn't improved by the acrid smell of burning flesh

[EternalOptimist]

Good advice there. BTW numbers of appliances store a potentially lethal charge in capacitors. E.g. a microwave - never dismantle one to DUY.

not just capacitors, collapsing fields as well. And if they have nowhere to go, they can persist for quite a while
it might defy all common sense, but some appliances, when you pull the plug out, can suddenly become live at the pins on the plug. You put your fingers across them and you would sure know about it
I got into the habit , may years ago, of treating unplugged stuff just like plugged in stuff. with great caution

[BlasterBates]

Nobody says cars are pretty harmless. That's why you have to take a test to show you can use one.

Yeah which is the point I was making.

I mean drving down the motorway, taking your chain saw to a tree trunk, eating a can of beans (Botchelism) and having a hot shower (Legoinaires) all carry risks that we need to weigh up.

In comparison to most of the above using a voltmeter to check your PSU is pretty far down the list.