# Electric shock : what risk working with a 6V power supply?

I am planning to cut the end connector of this power supply to work on it and build a dummy 4 LR6 1.5V pack.

But I wonder : is there a risk to have an electric shock manipulating those wires while the power supply is plugged ? Let's imagine that my pack is done and I touch the metal parts when the power supply is plugged into the wall.

What about using the same power supply with just 1A (item or item) or 2A power (item or item)

I wonder because I've read in many places things like the following (Google traduced) :

AC, we can retain these values​​:

1 A: Stopping the heart
40 mA to 75 mA: irreversible cardiac fibrillation threshold
30 mA: Threshold of respiratory paralysis
10 mA: Threshold not release, muscle contraction
0.5 mA: Threshold of perception, feeling very low

DC, we can retain these values​​:

130 mA: Threshold of cardiac fibrillation
??? : Threshold not let go
2 mA: Threshold of perception

So... with my 3A or even a 1A power supply... I'm worried.

• Oliver - don't be worried. As several people have noted, current matters BUT you have to get it to flow by using voltage. My comment about conductive gel and metal plates and spikes was actually serious enough - doing that MAY get enough current into your heart to cause problems. There will be very very very few occasions when you get a situation matching that one. See next ... – Russell McMahon Aug 1 '12 at 11:59
• ... POSSIBLE example. - Shirtless person carrying 12V (or maybe 6v) car battery on a hot day when their chest is very wet with sweat. Leaning the terminals hard against their sweaty chest as they carry the battery MAY cause a heart incident - but a broken foot as they release the battery is more likely. – Russell McMahon Aug 1 '12 at 12:00
• It is worth noting that much of the protective resistance we have comes from our skin. In a situation where that is broken, you can experience noticeable current flow from much lower voltages. – Chris Stratton Aug 1 '12 at 15:14

## 6 Answers

Electric shock : what risk working with a 6V power supply?

• It is unlikely that any one has ever been killed by a 6V supply.
If they have then somebody was doing something immensely stupid and very unusual.

• In almost all cases it is not possible to get any sort of noticeable shock with a 6V supply, because the voltage is too low to overcome the body's surface resistance and to 'drive" enough current into the body to be dangerous.

• Under very artificial conditions a person (a convict volunteer) volunteer died when 12V was applied across their chest with electrodes as part of medical research. This was an extremely unexpected result (medical team present I think). It would be even harder with 6V. You need to both get large surface area, good conductivity and probably skin penetration. Just as you can probably avoid sticking a hot soldering iron up your nose, as long as you do not do the above with your supply all will be well.

Personal experience:

• I have worked with low voltage (say 15V or less) in contact with my hands and arms for many many decades and have never experienced any sensation of shock or other effect.

"Taste" a fresh 9V transistor radio battery with your tongue and you may regret it a little. Tastes like very very strong lemon juice - but not as strong a "lemon" taste as having 33% concentrated Hydrochloric acid poured over your face. (Ask me how I know).

Telephone exchanges use 50V and have (or had) wiring frames. Workers on these frames come into frequent contact with 50V. Long long ago I worked in an exchange for a holiday job. Brushing 50V terminal pairs with your hands on dry days produces little or no effects. Doing it on a high humidity day may produce little annoying nips and bites. 75 VAC ringing which sits on 50VDC is much much less nice!

230 VAC will give you a nasty belt and can certainly kill you and is best avoided utterly - but many people have dozens of short contact shocks without ill effect. Including me. It's something I avoid like the plague as I grow older - so that I can keep growing older.

Contacting a 1,000VDC 1A supply leaves you pleased to be alive, if you still are. I am.

Flounder fishing cautionary tale:

• I have a friend who went flounder (flatfish) fishing in knee deep salt water with a combination LED light and flounder spear, using a 12V battery.
He experienced a

battery +ve
spear_shaft -
hand -
legs -
water -
spear_end -
battery -ve

"event" and found that he could not release the shaft due to current in his hand muscles. As long as you don't stand in salt water with salt water on your hand, gripping a large thick electrode connected to one battery or power supply terminal while the other terminal is connected to your legs by standing in salt water then you will probably not be able to replicate his experience :-).

The power pack will not give you a dangerous electric shock if you work with it turned on in an anything like sane manner. See at end for insane manners. The same applies to 1A and 2A supplies.

However, if you short the leads together there is a significant chance of destroying the supply, depending on how well it is designed and built. Power dissipation IF it made full voltage internally while shorted is ~+ 6V x 3A = 18 Watts. Many supplies will withstand a quick shorting together of the leads.

BUT it may have an internal fuse. If fast-blow (standard fuse) it will probably blow under short and will probably not be accessible. If it has an internal slow-blow fuse you may have from a fraction of a second to just maybe a few seconds before it blows.

If it has no fuse it MAY go into well behaved foldback or shut down or produce 3A and about 0V. BUT there is no guarantee that it will do this.

An unfused supply that is shorted MIGHT destroy output switch, diode, inductor, PCB track, connector. Never certain. Always possible if you do not know otherwise.

Shock- super extreme worst case:

If you coat your chest around your heart with high electrical conductivity gel and apply two large flat electrodes with small needle points sticking through them every few mm to the surface of your chest around your heart and apply 6V as above You MAY be able to kill yourself, but don't count on it.

If you do similar to muscles controlling breathing you MAY be able to lock your diaphragm to the extent that you cannot breathe and will die. But, don't count on it.

• IMHO it's more likely to be hit in your bed by a lightning entered from a window than to success in a suicide with the "tecnique" you just described... maybe one can try to hang himself with the cable... :D:D:D – Axeman Aug 1 '12 at 9:26
• @Oliver The currents in that table are current that must pass THROUGH THE HEART. With 6V and the resistance of your body, it's almost impossible to a dangerous current to reach the heart. FYI an arc welder have ad output of at least 30V, and an available current of more than 100A, but welder workers that electrocute themselves holding the electrode or the ground clamp are really rare :-) – Axeman Aug 1 '12 at 10:54
• @Oliver and all - Read all the comments people have made and try t understand what is being said. If you keep raising fallacious reasonings and bad formulae with no justification after people have spelled it out top you people are liable to get tired and go away. | Key concept is that current "follows along behind. Voltage attempts to drive current. Resistance resists voltage. Current occurs as a consequence of expression I = V/R. A 3A supply is capable of 3A but will only supply it when I = V/R >= 3. – Russell McMahon Aug 1 '12 at 16:20
• @Oliver 6V are constant simply because that power supply is a 6V CONSTANT VOLTAGE generator: it tries to keep a CONSTANT VOLTAGE and "let the current go as needed". You could have a 3A CONSTANT CURRENT generator, that is a circuit that tries to keep 3A flowing by increasing or decreasing the voltage as needed. And in that case (but a constant current generator without any other limitation is an impossible circuit) THE CIRCUIT WILL GIVE YOU SOME HEAVY SHOCK AND PROBABLY KILL YOU INSTANTLY. – Axeman Aug 1 '12 at 18:21
• @Oliver the simplest constant current generator I can think about is a "dumb" NiCd/NiMH cell charger. Is a circuit made to supply a constant current to the cell pack, without caring about voltage of pack or charge state. And it does that by varying the voltage on the output between 0v and the max voltage that the circuit can handle... – Axeman Aug 1 '12 at 20:56

It's not the voltage but the current which is dangerous. But the 6 V supply will only deliver the 1 A if it's allowed to, i.e. if the resistance is low enough. Per Ohm's Law

$I = \dfrac{V}{R}$

so a high resistance will give you a low current, no matter what the batteries are able of. I measured the resistance on my skin between two fingers on the same hand, two points on the same finger, between both hands, etc, and I never measured a resistance lower than 200 kΩ. Even with wet hands it was never below 38 kΩ. Then according to Ohm a 6 V battery won't supply more than 160 µA, which, according to your data, is ten times lower than the perception threshold.

Even if the battery could supply 1000 A it wouldn't do you any harm. The current depends on the resistance, not on the power supply's capacity.

To feel an electric shock from a 6V source like that (provided that it's well insulated from mains) you'll have to touch both poles with your tongue :-).

The usual disclaimer apply: DON'T TRY TO DO IT... it's painful ;-)

• Why shouldn't he do it? It's how I used to test 9V batteries as a kid :-) – lyndon Aug 1 '12 at 12:24
• I still do it. But a 9V battery has an internal resistence so high that it limitates the current you can get from the battery even with a short circuit. A 3A power supply does not have that "safety feature". You can try but, trust me, you'll be unpleasantly surprised... :D – Axeman Aug 1 '12 at 12:35
• You can get >3 amps out of a 9 V battery, at least for short periods of time. Needless to say, the low voltage and relativity high resistance of the tongue is the limiting factor, not the sub-10 ohm internal resistance. – exscape Aug 1 '12 at 13:15
• @exscape I've measured the short circuit current of a few 9V battery, and it never exceeded 1A. Moreover years ago I've "checked" with the tongue what I thought was a clip cable connected to a 9V battery but it was actually connected to a 9V DC 2A power supply... and it wasn't pleasant at all... way stronger than a "normal" 9V battery – Axeman Aug 1 '12 at 13:32
• I measured one just days ago, shorting it through a 10 A multimeter jack, and it read over 2 amps for the few seconds I held it in place. Hmm. Alkaline battery FWIW. – exscape Aug 1 '12 at 13:33

Most countries in the world have power supply regulations that specify a voltage below which it is deemed to be 'safe', that is the terminals do not need to be insulated against human contact to avoid electric shock.

The exact voltage varies a little from region to region, but they all agree on somewhere around 40v. Anything below that and there simply isn't the voltage available to drive a dangerous current through typical human skin on a casual touch.

Touching your tongue with 6v, you will get a tingle, but nothing life threatening.

No shock should be taken lightly. PERIOD! Each individual will react differently based on bmi .. current physical condition. If you experience stammering or stuttering in your speech along with muscular contractions ... SEEK MEDICAL HELP .. IMMEDIATELY! This could be a condition of a cardiac episode! People on here have posted that no one has ever died because of a 6v shock .. SIMPLY NOT TRUE !!! There have been deaths and serious injuries from motorcycle batteries that where 6v. Like I stated .. it depends on the INDIVIDUALS health.

• I find very, very difficult to believe that somebody can be shocked by 6V. Like I think it's plainly false. – Vladimir Cravero Aug 26 '15 at 9:30

When considering electrical devices and electronic products generally there are a limited (one up to possibly 2 dozen in more complex circuits-devices*BUT*, the human body presents a VERY different scenario / electrical picture!

Every human cell (except dead cells) conducts some energy (skin the least i.e. HIGHEST resistance, flesh / organs the most i.e. lowest resistance). So as soon as you consider current flow below the outer dermis-skin, current has many dozens if not hundreds or even thousands of paths to divide between. The 'rule' is, current divides inversely proportional to the resistance of each/every possible path

The above in NO WAY is intended to minimize, dismiss, understate, nor disregard the IMPORTANCE of safety and prudent precautions. Electricity can KILL and usually without any warning! I won't bore readers with the details, but when I 'thought' I knew what I was doing, my being THROWN OFF my bed SAVED my life! Years later my Father lost his life because he failed to consider the arc traveled by a TV antenna attached to a 20' pole/mast travels ABOVE the top of the pole/mast as it is tilted upward.

• At 6V? I am sorry, but this reads as mostly nonsense to me and I see very little actual valid information. As someone whom works with actual dangerous voltage levels and supplies that can supply 100s of amps at 6V the only risk you have from 6V is vaporizing a tool and hurting yourself from the explosion. This is also the primary way people are actually killed from arcs, not from being electrocuted. – Kortuk Aug 4 '12 at 14:41