24 volts DC
- Thread starter jaguar1
- Start date
it depends on a few factors..
if you're sweatty and leaning on it with a soft part of your anatomy they you will feel the tingle ( same as a 9V battery to the tongue ), but a dry part that's hard skinned ( such as a calloused hand ) won't feel it up until about 40V or so..
this is not to say that it's safe to work live, there's always a chance that you're particularly conductive and have a weak heart so it's not worth the risk.
bear in mind that the recommended safe "touch" voltage is 50Vac ( ie 50Vac accross the wrong part of your body is enough to potentially kill you.. )
if you're sweatty and leaning on it with a soft part of your anatomy they you will feel the tingle ( same as a 9V battery to the tongue ), but a dry part that's hard skinned ( such as a calloused hand ) won't feel it up until about 40V or so..
this is not to say that it's safe to work live, there's always a chance that you're particularly conductive and have a weak heart so it's not worth the risk.
bear in mind that the recommended safe "touch" voltage is 50Vac ( ie 50Vac accross the wrong part of your body is enough to potentially kill you.. )
And even it it doesn't shock you, you can still receive some very nasty burns if you short a piece of metallic jewellery across it 
It depends..... All sorts of things can influence skin resistance - humidity, temperature, the thickness of the skin it comes into contact with, even the type of shoes you're wearing, and how many beers you had the night before 
In my previous job I often encountered 50V DC, and thought little of it, but on some days, it definitely tingled more than on others!
On one occasion, someone had neglected to replace the covers on terminals carrying commutating +80 /- 80v V DC, which i brushed with the inside of my forearm - That made me step backwards a bit sharpish like!
Skin resistance is usually reckoned in the Kilohm to Megohm range, so you would have to be very unfortunate for enough current to flow to get more than a mild shock.
Dropping a spanner across the terminals of a lead acid battery isnt really comparable to the chance of electrocution by touching the terminals with the hand. Lead acid batteries generally have an internal resistance of about 3/10ths of FA, as does the average spanner. The result of the dropped spanner scenario is a massive current flow through said spanner causing it to melt, acid burns etc from the contents of the battery as the top blows off from excessive pressure as the electrolyte boils, and shapnel wounds and fires caused by the scattered remains of both battery and molten spanner. Not exactly electrocution, but probably many times more dangerous!
In my previous job I often encountered 50V DC, and thought little of it, but on some days, it definitely tingled more than on others!
On one occasion, someone had neglected to replace the covers on terminals carrying commutating +80 /- 80v V DC, which i brushed with the inside of my forearm - That made me step backwards a bit sharpish like!
Skin resistance is usually reckoned in the Kilohm to Megohm range, so you would have to be very unfortunate for enough current to flow to get more than a mild shock.
Dropping a spanner across the terminals of a lead acid battery isnt really comparable to the chance of electrocution by touching the terminals with the hand. Lead acid batteries generally have an internal resistance of about 3/10ths of FA, as does the average spanner. The result of the dropped spanner scenario is a massive current flow through said spanner causing it to melt, acid burns etc from the contents of the battery as the top blows off from excessive pressure as the electrolyte boils, and shapnel wounds and fires caused by the scattered remains of both battery and molten spanner. Not exactly electrocution, but probably many times more dangerous!
In my mind there is no such thing as 'safe touch' when it comes to ANY electricity.
Yes, when I was younger, along with 99% of the population, I used to put a 9v battery on my tongue, even had competitions to see who could last the longest.
However, a friend of mine, (not a close one but knew him well), was tinkering with his phone line. He got a zap. Unknown to him he had a heart problem that neither he, his wife or even his mother knew about. It really shook him up when he felt it and a few hours later told his wife he didn't feel well. Taken to hospital where they discovered he had something called ventricular blah, blah. Anyway, it was enough to put him in the cardiac unit for a week and the docs blamed it on messing with the 'live' phone wires.
Yes, when I was younger, along with 99% of the population, I used to put a 9v battery on my tongue, even had competitions to see who could last the longest.
However, a friend of mine, (not a close one but knew him well), was tinkering with his phone line. He got a zap. Unknown to him he had a heart problem that neither he, his wife or even his mother knew about. It really shook him up when he felt it and a few hours later told his wife he didn't feel well. Taken to hospital where they discovered he had something called ventricular blah, blah. Anyway, it was enough to put him in the cardiac unit for a week and the docs blamed it on messing with the 'live' phone wires.
R
roberta1000
Unlucky fellow - you'd generally be OK of course but the ring voltage on a line can certainly give you a nasty tingle.
You can easily generate transients of hundreds ov volts playing around with a 12V battery and a circuit with a little inductance. This is the principle used for Tasers and they can certainly make perps do more than jump around.
Your main concern when working with 24VDC is that you do not short circuit the power supply and cause damage to it or other devices powered from it.
If the power supply is of high enough wattage a short circuit in theory could cause a burn if your skin happens to be next to where the short is occuring since heat and possible arcing can occur.
On the whole though it is considered a safe voltage to work on live.
If the power supply is of high enough wattage a short circuit in theory could cause a burn if your skin happens to be next to where the short is occuring since heat and possible arcing can occur.
On the whole though it is considered a safe voltage to work on live.
I thought they used capacitor / diode ladders? like they use in ionisers to generate several thousand volts..
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As already said 24vdc will rarely give one a shock. However disconnecting items supplied from 24vdc often gives one a shock.
It is referred to as "Back EMF" and even on a 12vdc system if you open the contacts feeding an ignition coil you can get 250v as the field in the coil discharges into the capacitor.
Relays can also produce back EMF and often they are fitted with diodes to stop it damaging switches.
With wagons and like using alternators where cables have broken the alternator can produce 110 volt AC with ease and this can make one jump some what. With modern alternators with the integral regulator this is less of a problem.
So disconnecting batteries can give one a nasty shock. Of course there are units designed to increase the voltage one which seems to catch people out is the florescent lamp and even a 8 watt tube needs around 60 volts to run and more like 250 volts to fire. Although supplied with 12 or 24 volts that is not fed to tube.
It is referred to as "Back EMF" and even on a 12vdc system if you open the contacts feeding an ignition coil you can get 250v as the field in the coil discharges into the capacitor.
Relays can also produce back EMF and often they are fitted with diodes to stop it damaging switches.
With wagons and like using alternators where cables have broken the alternator can produce 110 volt AC with ease and this can make one jump some what. With modern alternators with the integral regulator this is less of a problem.
So disconnecting batteries can give one a nasty shock. Of course there are units designed to increase the voltage one which seems to catch people out is the florescent lamp and even a 8 watt tube needs around 60 volts to run and more like 250 volts to fire. Although supplied with 12 or 24 volts that is not fed to tube.
You probably could, if you wanted one, although it might depend on where you wanted it...
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I bet when you were young you were one of those who bridged electric fence to normal one near a place where people would re-leave themselves?You probably could, if you wanted one, although it might depend on where you wanted it...
"Fly the scull and cross legs"
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how on earth can it be more dangerous than electoruction
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