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

amperagepower 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.

Best Answer

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.

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