Can a PSU kill you?

[orangecat]

What would happen if you touched the ground and lets say a +5v or +12v rail? If you completed a circuit is there enough power to kill you?

[MdX MaxX]

I suppose?  You have tens of amps of current flowing on those rails, which is enough to kill you hundreds of times over.

 

I could be wrong, though.  I'm not really a circuits guy.

[Vitalius]

There was a news story a year or two ago that was about a boy who got electrocuted while messing with the insides of his PSU and died.

It was unplugged, the capacitors in it still had enough charge to kill him.

So yes, it can. And likely will.

[MegaDave91]

If you're working inside your case, prior to opening the case, you should hold the power button for a few seconds even after the power cable is unplugged from the power supply to discharge any lingering electricity.

 

Power supplies aren't really user serviceable are they? The kid shouldn't have opened it up.

[nelodiavolo]

I would say that it could, especially if still connected to the wall, and even then like Vitalius said, it happened even when unplugged. I always unplug my power supply before working in my computer. I also don't go messing about inside one for the off chance there is still electricity in the components. 

[Skyfire]

Heck yeah it could. If you threw it hard at someone's head, it'd probably knock them out cold and cause a severe haemorrhage. 

[brownninja97]

To  get rid of the charge just take the power plus out and hit the power button. Notice that your fans might start and then stop after a second, that is the charge and after that you should be a lot more safer, not 100% but much more then before.

[Chipset]

Unless you open it up and/or poke around inside it while it's plugged into the wall then absolutely no. Even the charged electrolytic capacitors aren't very dangerous when the device isn't plugged in.

Contrary to what anyone will tell you, the amps are not the killer. Technically the amps are what kills you, since amperage is the measurment of the actual flow of electrons, but just because something can deliver a shitton of amps does not mean it's dangerous to a person. Skin and flesh has a resistance to the flow of electricity, the epidermis (outermost skin layer) is especially good at this and can provide several million ohms of resistance. Ohms law (V/I=R) says that at a given voltage, the resistance determines the amperage. Thus, touching a car battery fully charged to 12 volts with a typical skin resistance of 100k ohms, you would only have 120µA flowing through your body, more than 100 times smaller than the 20 or so milliamps needed directly across the heart to cause ventricular fibrillation. Keep in mind that for an electric current passing through your body to be seriously harmful or lethal, it needs to pass vital organs or your nervous system/brain. For this reason, arm to arm contacts are most dangerous, that's where you touch one polarity with each hand so the current passes through your chest.

Excluding extraordinary circumstances, no voltage below about 30 volt can possibly be dangerous to a person and you need to get upwards of 60-100 volts before there's ANY kind of danger.
The only time where voltages lower than about 100 volts can be dangerous or lethal is when both of the points of contact bypass the skin, as flesh and tissue have much much lower resistances.

When contacting the skin, voltages over about 50 volts can cause slight discomfort or pain, voltages over 100 volts can be very painful and are potentially dangerous and voltages of about 200 volts or above are potentially lethal. Any voltage over 100 volts should be treated with respect, as if it could kill you, to prevent any accidents. Voltages over about 200-300 volts should be treated with extreme caution as these could potentially be instantly lethal, depending on the way you contact them.

But back to the subject at hand, a charged electrolytic capacitor, even those big ones inside a PC power supply used for smoothing rectified mains voltages simply does not contain enough energy to kill a person.
You'll get a hell of a shock if you bridge the connection with your finger, you'll get a burn mark and you'll be feeling it for hours, but you won't be dead. This is because the current drops off too fast as the capacitor discharges through you.
An analogy would be that flicking your finger through a candle flame won't burn you because the contact time isn't enough, there's not enough exposure time to heat up the skin to give you any burns.

[rhoscrazy]

What would happen if you touched the ground and lets say a +5v or +12v rail? If you completed a circuit is there enough power to kill you?

[YellowDragon]

Yes a PSU can kill you, My EVGA NEX 1500 SuperNova PSU has 160A combined on a single rail, in short it can drop you and a herd of elephants all at the same time.  

[Chipset]

Yes a PSU can kill you, My EVGA NEX 1500 SuperNova PSU has 160A combined on a single rail, in short it can drop you and a herd of elephants all at the same time.  

 

NO

THAT'S NOT HOW ELECTRICITY WORKS

AMPERAGE DOES NOT KILL

YOU NEED VOLTAGE OF WELL OVER 100 VOLTS TO DELIVER ENOUGH CURRENT TO YOUR HEART TO HAVE ANY EFFECT

LOW

VOLTAGE

CANNOT

KILL

EVER

GAAAAAAAAH

[YellowDragon]

NO

THAT'S NOT HOW ELECTRICITY WORKS

AMPERAGE DOES NOT KILL

YOU NEED VOLTAGE OF WELL OVER 100 VOLTS TO DELIVER ENOUGH CURRENT TO YOUR HEART TO HAVE ANY EFFECT

LOW

VOLTAGE

CANNOT

KILL

EVER

GAAAAAAAAH

I think your forgetting that a PSU converts from AC to DC so yeah you can run into an instance where you get 120v AC at a high amperage during the conversion process if you touch the right components, after all your not touching the modular connections of the psu which deliver 12v DC. So you are right to an extent, however i never specified the part of the psu you were touching. Also you mentioned a charged electrolytic capacitor would not be able to kill you, I wonder if you have seen the ones in the very large PSUs there the size of a small pill bottle at that point, no to mention everyones body chemistry is different so one thing might be lethal to someone but not to someone else. I think the moral of this story is just dont open up a psu and tinker around unless you know what your doing or you risk severe injury.

[orangecat]

Unless you open it up and/or poke around inside it while it's plugged into the wall then absolutely no. Even the charged electrolytic capacitors aren't very dangerous when the device isn't plugged in.

Contrary to what anyone will tell you, the amps are not the killer. Technically the amps are what kills you, since amperage is the measurment of the actual flow of electrons, but just because something can deliver a shitton of amps does not mean it's dangerous to a person. Skin and flesh has a resistance to the flow of electricity, the epidermis (outermost skin layer) is especially good at this and can provide several million ohms of resistance. Ohms law (V/I=R) says that at a given voltage, the resistance determines the amperage. Thus, touching a car battery fully charged to 12 volts with a typical skin resistance of 100k ohms, you would only have 120µA flowing through your body, more than 100 times smaller than the 20 or so milliamps needed directly across the heart to cause ventricular fibrillation. Keep in mind that for an electric current passing through your body to be seriously harmful or lethal, it needs to pass vital organs or your nervous system/brain. For this reason, arm to arm contacts are most dangerous, that's where you touch one polarity with each hand so the current passes through your chest.

Excluding extraordinary circumstances, no voltage below about 30 volt can possibly be dangerous to a person and you need to get upwards of 60-100 volts before there's ANY kind of danger.

The only time where voltages lower than about 100 volts can be dangerous or lethal is when both of the points of contact bypass the skin, as flesh and tissue have much much lower resistances.

When contacting the skin, voltages over about 50 volts can cause slight discomfort or pain, voltages over 100 volts can be very painful and are potentially dangerous and voltages of about 200 volts or above are potentially lethal. Any voltage over 100 volts should be treated with respect, as if it could kill you, to prevent any accidents. Voltages over about 200-300 volts should be treated with extreme caution as these could potentially be instantly lethal, depending on the way you contact them.

But back to the subject at hand, a charged electrolytic capacitor, even those big ones inside a PC power supply used for smoothing rectified mains voltages simply does not contain enough energy to kill a person.

You'll get a hell of a shock if you bridge the connection with your finger, you'll get a burn mark and you'll be feeling it for hours, but you won't be dead. This is because the current drops off too fast as the capacitor discharges through you.

An analogy would be that flicking your finger through a candle flame won't burn you because the contact time isn't enough, there's not enough exposure time to heat up the skin to give you any burns.

Makes allot of sense. Thanks for the input.

[orangecat]

 

What would happen if you touched the ground and lets say a +5v or +12v rail? If you completed a circuit is there enough power to kill you?

 

I don't get it.

[nickpc]

yes

[ObeseWalrus]

It will kill you. And yes, it will hurt.

[Steowd]

It will kill you. And yes, it will hurt.

how do u know it will hurt if it will kill you aswell ?

[JordanMac]

depends, if it grounds across your heart you're gone. there are people that get struck with lightning etc that survive because the current went in the left arm and out the left leg and didn't go across the heart.

[FireFox]

I suppose?  You have tens of amps of current flowing on those rails, which is enough to kill you hundreds of times over.

 

I could be wrong, though.  I'm not really a circuits guy.

Only need to be killed once, also remember you only need something like 4 amps to weld with, if 20A or more is running through the PSU or more it could easily kill you plus you have (here in the UK) 230-240v going into the PSU.

 

Car batteries only have 12v but hundreds of amps and you can touch both terminals without it doing anything to you so it really depends on the voltage I'd imagine.

[KaareKanin]

What @Chipset said. A normally functioning PSU will not kill you a normally functioning you. Simple as that ;-)

(but if you wanted to, you could turn it into something lethal)

[ObeseWalrus]

how do u know it will hurt if it will kill you aswell ?

You won't die instantly

[IvIast3r]

it not the voltage or the wattage that kills, its the amount of amps, and it takes less than 1 amp to kill.

[FireFox]

it not the voltage or the wattage that kills, its the amount of amps, and it takes less than 1 amp to kill.

 

Quite a lot less than a single amp, I think somewhere around 180-220mA can stop your heart, if not I don't think you'd be too well lol

[Chipset]

it not the voltage or the wattage that kills, its the amount of amps, and it takes less than 1 amp to kill.

But you need a high enough voltage (100+) to let enough current pass through the resistance of the skin to be dangerous.

"It's the amps that kills you" is technically correct but dangerously misleading if you don't understand electricity.

[Fetzie]

But you need a high enough voltage (100+) to let enough current pass through the resistance of the skin to be dangerous.

"It's the amps that kills you" is technically correct but dangerously misleading if you don't understand electricity.

The electricity going in to the PSU is 240V (110V in the USA). Touch the bit before the voltage is reduced and the power rectified and you could do some serious damage to yourself. Somebody that needs to ask if they will die if they open their PSU isn't going to know which parts are safe (3.3, 5, 12V) and which aren't (110/240V). So just don't.