The problem is that things like safe shock current and duration are very Physiology dependent.

A vet specialising in primates or pigs may well read across what is needed from humans, but some one doing mostly cats or birds probably cannot. Disconnection times ought to scale with heartbeat period, so smaller animals like mice will go into fibrillation in a far shorter time than elephants or heavy horses. (I do not have a good reference for that.)

The choice has to be driven by the medical considerations  - BS7671 being written by electrical subject matter experts, therefore, quite correctly says nothing beyond "refer to the experts".

The whole zone groups and shock levels thing is really derived for humans on the operating table and assuming a  human heart and lungs, As soon as this assumption is invalid so is the rest.

By all means use the 710 material as a starting point but do not get hung up if it ends up being decided that something else, or even no special measures at all, makes more sense.

Mike.

mapj1 said:

so smaller animals like mice will go into fibrillation in a far shorter time than elephants or heavy horses

Strange thing is that fibrillation (of atrium or ventricle) can be fixed by a shock. Trust me, I have had it done!

Hi Chris, I’m sorry to hear that you had to go through such a frightening experience. Fibrillation is a serious condition that can affect the heart’s ability to pump blood effectively. I’m glad that you were able to receive the treatment you needed and that you are doing well now.

AMK, thank you. Atrial fibrillation, which I had is more of a nuisance than anything else; ventricular fibrillation (which can occur after an electric shock) is fatal if not treated within a few minutes. That's why defibrillators are carried in ambulances, etc.

My experience was not at all frightening because it was used for the former. The irritating bit was that the cardiologist insisted on sedation so I was not conscious at the time and experienced nothing.

AMK, thank you. Atrial fibrillation, which I had is more of a nuisance than anything else; ventricular fibrillation (which can occur after an electric shock) is fatal if not treated within a few minutes. That's why defibrillators are carried in ambulances, etc.

My experience was not at all frightening because it was used for the former. The irritating bit was that the cardiologist insisted on sedation so I was not conscious at the time and experienced nothing.

According to the commentary on BS 7671 book, the timing of the shock in relation to the cardiac cycle is a critical factor for the outcome. For example, if the shock coincides with a certain point, it can induce ventricular fibrillation, which as you described is a condition where the ventricles of the heart tremble instead of contracting blood. This is a life-threatening situation that requires urgent defibrillation. However, was it a shock that caused your atrial fibrillation ?  (atria of the heart beat irregularly). So this is what You experienced ? and did you undergo a procedure called cardioversion to correct it ? (low-energy electric shock that is synchronized with the heart’s natural rhythm) but has anyone ever experienced an electric shock? How did it affect you? What did you do about it?

AMK said:

has anyone ever experienced an electric shock? How did it affect you? What did you do about it?

Slightly closer to the original thread ...

My first was at the age of about 8. We had lamps attached to the bed head and they were operated by a switch on a dangling bit of flex. Mine fell off in the night so when I reached up in the morning I touched a live cable. I have never before or since least out of bed so quickly.

My most recent time was when re-wiring daughter's house. I could not isolate the whole installation because she and other tradesmen wanted power, but I had isolated the downstairs lights and proved dead. Problem was that one of the light switched was connected to a different circuit. I swore!

(The place was a potential death trap - one ordinary sized room had sockets powered by three different circuits.)

Apart from the obvious learning point about proving dead all the time, I think that the experiences were merely unpleasant because I was somewhat insulated from the general mass of the earth and I was able to let go.

I experienced my first electric shock when I was a 17-year-old apprentice. I was assigned to replace a socket in a pub kitchen. I verified that the socket was not live and proceeded to disconnect it. I had both ends of the ring line conductor in my hands, when suddenly I felt a jolt of pain. I heard a loud scream and wondered who was making such a racket, only to realize that it was me. The electrician I was working with had turned the circuit back on without warning me! It was a shocking experience, literally and figuratively. 

but has anyone ever experienced an electric shock?

Oh yes - quite a number of times (mostly as the result of a mis-spent youth in the days before elves & safety).

Earliest I recall I must have been about 6 - I'd noticed that the 2-bar electric fire in the front room seemed to take a long time after switching for the elements to start glowing. I wondered if they were getting hot before they glowed. To try and answer my own question I decided to try to put my hand on one of the element to feel how hot it was, but realizing that if it was very hot I could get burned, I decided to put my hand on the element when it was definitely cold and then switch on with my other hand - my reasoning being that I'd then have time to pull my hand back through the guard as soon it started to get warm, before it got too hot. However my safety precautions didn't include an understanding of electricity at that time - but I learned very quickly that: a) electricity hurt (a lot), and b) it pulls (so not so easy to get your hand back).

A bit later there was the experiment with my Grandmothers 2-pin plugs you could get at the live parts just by spinning the lid off...

Then a few experiments in my teens (mainly trying to switch mains via triacs) which wouldn't have held water in a modern risk assessment...

In adult life I seem to have been relatively safe ... until I was asked to replace a shower pull switch (odd sort of rental place - lots of office style suspended ceilings) - isolated the shower circuit, proved dead, got a belt when I touched the c.p.c.  Double checked the c.p.c. - definitely at 0V - turned out the metal ceiling grid was live from a combination of a fault in another room, break in a lighting circuit c.p.c. and class 1 fittings attached to the grid. Sometimes you just can't win.

    - Andy.