3v supply gives a shock??????

[SealionSteve]

Hi

 

I have some LED lighting  which I was recently testing (there was no power being fed anywhere else on the layout). I used a twin AA battery holder with a couple of fly leads and touched them to the wires from the LEDs. I was suprised to feel a "shock" when my fingers touched the wires. OK, not agonising, but definitely an electric shock - "hot" enough to make me drop the wires and say something naughty! I always thought that "the volts give you jolts but the amps put out your lamps", so I was a bit confused! Should 3v from 2xAA batteries feel painful?

 

Cheers,

 

Steve 

[Miss Prism]

Alternative version: "It's the volts that thrills, but the amps that kills"

 

[AndrueC]

Reminds me of the time I gave myself a 12v jolt from a layout my Dad built. I was reaching under the baseboard to reset the breaker and touched the supply joints instead. It was a bit painful but what really hurt was that I pulled my arm back and hit my funny bone on a window ledge.

[Hibelroad]

I cannot think of any circumstances in which 3v would be felt in the fingers, could it have been a sharp strand of wire stabbing the finger?

[SHMD]

Amps will only cause you a problem if...

 

A/ There is enough "volts", behind them, to force the "amps" through you! (A shock.)

B/ There are "a lot" of amps, normally in the circuit, and you provide a short(er) circuit for them. (A fire hazard.)

C/ There aren't enough amps for what you want them to do! (The thing doesn't work!)

 

 

Was the layout wiring complete and the LED circuit connected to a PSU (of some sort) but currently switched off?

 

 

Regards,

Kev.

[stewartingram]

I used to work for Pye/Philips in Cambridge. Now if you've ever watched the Proffesionals on TV back in the 80's, they "used" Pye PF8 handportable radios (they were actually empty cases), which apparently worked everywhere they went (not possible with a live one, they had limited range).

Now the point is they were powered by a (to Pye) new-fangled re-chargeable battery. Think of an AA re-chargeable, they were that sort of size, but actually not quite - they sold more because no-one else made them. They were an all metal case too, no insulation; the +ve terminal on the end was like a present day CR2032 button battery, just a small insulated gap to the outer case -ve, the gap was about 1mm.

Put a fully charged one in your pocket with your car keys, they shorted it out and burnt a hole in your pocket. They were only 1.2v, but if you shorted them out with an AVO 8 multimeter on the 10A range and the needle hit the stop. They gave 10A and more!

One of my fellow workers shorted one with his wedding ring, that welded to the battery and caused a quite severe burn under the ring before he broke the battery away!

Treat elecktrickery with respect - always.

[SealionSteve]

Hibelroad - could have been, I suppose. Next time I'm feeling masochistic I will do a controlled experiment 🥴 SHMD - nothing else connected, just the wires from the (Kytes Lights) lamps held by me against the 2 wires from a 2xAA battery holder. 

 

Thanks all! Liked the Professionals anecdote!

 

 

[peterm1]

8 hours ago, stewartingram said:

I used to work for Pye/Philips in Cambridge. Now if you've ever watched the Proffesionals on TV back in the 80's, they "used" Pye PF8 handportable radios (they were actually empty cases), which apparently worked everywhere they went (not possible with a live one, they had limited range).

Now the point is they were powered by a (to Pye) new-fangled re-chargeable battery. Think of an AA re-chargeable, they were that sort of size, but actually not quite - they sold more because no-one else made them. They were an all metal case too, no insulation; the +ve terminal on the end was like a present day CR2032 button battery, just a small insulated gap to the outer case -ve, the gap was about 1mm.

Put a fully charged one in your pocket with your car keys, they shorted it out and burnt a hole in your pocket. They were only 1.2v, but if you shorted them out with an AVO 8 multimeter on the 10A range and the needle hit the stop. They gave 10A and more!

One of my fellow workers shorted one with his wedding ring, that welded to the battery and caused a quite severe burn under the ring before he broke the battery away!

Treat elecktrickery with respect - always.

Going a bit off topic... what's new? Many years ago as a youngster learning the trade as a mechanic I watched an electrician taking a battery out of a Bedford J type small lorry. The battery was in the nearside cab floor. There was a shout of some lovely language and said electrician ended up with part of one (ring) finger burnt away. Believe it or not, this electrician had undone and removed the live lead and got his finger caught between spanner, lead and metal floor. Quite a mess. Even I at the tender age of 15 or 16 new not to do that. Earth lead first off, last on.

[cliff park]

Having worked in electronics all my life I would say anything less than 20 volts you cannot feel, 50 volts will give a tingle, 100 volts will definitely make you jump. I have occasionally been in contact with 250 volts, really makes you jump. Try

[RAF96]

A battery will give unlimited amps within its capacity if dead shorted, so even a little battery can hurt if you are in contact with the metal creating the short.

I saw a spanner drop onto a car battery once. It was smoking hot before someone had the sense to smack it free with a hammer.

You have never been shocked until you have felt HF current try to use you as a path to earth - not to be recommended. There is a good reason why painters and electricians work with one hand in their pocket, the former doesn't touch wet paint and the latter doesn't provide an earth point.

Edited May 4 by RAF96

[Michael Hodgson]

2 hours ago, cliff park said:

I have occasionally been in contact with 250 volts, really makes you jump. Try

 

I think you meant try not to ?

[Michael Hodgson]

1 hour ago, RAF96 said:

There is a good reason why painters and electricians work with one hand in their pocket, the former doesn't touch wet paint and the latter doesn't provide an earth point.

 

Recommended career opportunities for one-armed men?

Other than banditry, I suppose.

[Crosland]

3 hours ago, cliff park said:

Having worked in electronics all my life I would say anything less than 20 volts you cannot feel, 50 volts will give a tingle, 100 volts will definitely make you jump. I have occasionally been in contact with 250 volts, really makes you jump. Try

Don't try 400 V DC. Don't ask how I know.

[stewartingram]

4 hours ago, RAF96 said:

A battery will give unlimited amps within its capacity if dead shorted, so even a little battery can hurt if you are in contact with the metal creating the short.

I saw a spanner drop onto a car battery once. It was smoking hot before someone had the sense to smack it free with a hammer.

You have never been shocked until you have felt HF current try to use you as a path to earth - not to be recommended. There is a good reason why painters and electricians work with one hand in their pocket, the former doesn't touch wet paint and the latter doesn't provide an earth point.

And an electrician should never cross his hands.

[WIMorrison]

A major factor in whether you will feel anything is the skin on your hands and the condition of said skin at the time. If you are a manual worker then you are liable to have thicker skin on your hands than an office worker and this will affect the resistance of the skin. It is also true that some people have something we used to call 'rusty hands' because they had a natural tendency to be damp from sweat and the effect of them touching any clean, untreated metal surface was a rusty fingerprint on the workpiece after a period where they had touched the item. These people had to wear gloves to stop this effect.

 

if it was warm and/or your hands were just slightly damp (perhaps you had washed them just before the shock) then you will almost certainly feel something, but if it was DC then you would not feel it constantly, only when the initial contact was made.  If you felt it constantly, which is what you seem to suggest)  then it was not a DC supply from a battery that you were feeling, but an AC supply which would suggest that something was connected that you thought was switched off.

[SHMD]

Another source, that needs to be eliminated, is static electricity.

Namely the floor and shoes used.

 

Some hotels, I stay in, give me a zap every time I touch my rooms door handle!

 

 

Kev.

[andyman7]

On 04/05/2024 at 08:32, cliff park said:

Having worked in electronics all my life I would say anything less than 20 volts you cannot feel, 50 volts will give a tingle, 100 volts will definitely make you jump. I have occasionally been in contact with 250 volts, really makes you jump. Try

I remember once as a child (maybe 10 years old?) being at a friend's who was operating their train set 'loose laid'. Whilst the train was running I pushed two pieces of track together that were drifting apart and felt the distinct tingle of the current - it's the only time that ever happened to me!

[SealionSteve]

I can't say I ever felt anything off a 12v supply although some years ago when I hooked up a Relco "track cleaner" to my 12v dc layout and leant across the rails, touching them, it certainly hurt! I'm beginning to think Hibelroad may be onto something as 2xAAs has never hurt me before!

Edited May 5 by SealionSteve

[jcm@gwr]

I think it has a lot to do with skin resistance, or something like that.

Many years ago, 2 of my school mates (both car enthusiasts, like a number of us) joined the AA

as patrolmen. One couldn't change a sidelight lamp for a member, without turning off the lights,

because he'd get a shock. The other could touch the HT leads to check for a misfire!

Also, when I was a S/E mechanic, I had a number of YTS lads, one of whom used pull off the HT

leads (while the engine was running) and put it on his finger! He said it gave him a little tingle!

[Free At Last]

I had no problem holding the leads of a 500v Megger insulation tester, other electricians were terrified of it. The trick was to hold tight and not let go when you first feel it, you could then hold it all day.

Edited May 5 by Free At Last

[Siberian Snooper]

A late friend of mine Keith, who was a foot surgeon, was very susceptible to electric shocks, he was oiling round one day and another mate Jerry, a telephone engineer grabbed hold of the ring main conduit and touched Keith on the back of his neck, who then jumped about a foot, from the shock. An oft repeated jape, whenever Jerry could sneak up on Keith and something electric was to hand.