The double light switch at the top of our stairs broke this morning. I had a spare so I replaced it - no big deal.
Except that I forgot that the two lights controlled by the switch - the landing and the bathroom - are on different circuits. I turned off the upstairs light circuit but forgot about the bathroom one. :smack:
So, I’m trying to get the most inaccessible wire to go into the back of the new switch, as there’s not much slack to play with, and I end up grabbing the exposed end of the brown live cable between thumb and forefinger and shoving it into place.
No jolt, no flash, no being blasted down the stairs, just a modest tingling feeling in my hand that made me think, “Hmm, there must be some current in here” and let go.
Was I incredibly lucky or is there a reason I didn’t get zapped? I’m in the UK so that is 230 volts.
I saw my first dead body when I was about 14 and at boarding school. A fully qualified electrician was replacing the celing fixture on a lamp. He had cut the power from the lighting circuit then and stuck a finger in the socket to make sure it wasn’t live before he dismantled it… It was. He was standing on a steel framed chair on a damp concrete floor and the 240 volts going from his extended right hand to the soles of his feet was enough to stop his heart.
It turned out that he had pulled the wrong fuse. Apparently, a finger was a perfectly normal test that he would have done hundreds of times. This time he was unlucky.
An electrical shock is most dangerous to a body when current passes through the heart, either from hand to hand, or hand to foot. a current of .1 to .2 amps (especially AC) is capable of kicking your heart into ventricular fibrillation, and it won’t recover unless someone gets to you quickly with paddles. larger currents will generally just cause the heart to contract and stop beating until the shock is removed, but then there’s also the risk of internal burns to your organs.
so, in short, you were OK because you didn’t form a circuit with anything, and just felt the tingle of voltage in your hand.
Sounds logical. Some people have a naturally higher resistance, as well, or heavily calloused fingers that helps to moderate the jolt. I’m not one of them. The few times that I was careless as an electrician resulted in a nasty jolt that I felt clear up to my shoulder. Other electricians would check for voltage with their fingers, which I always considered to be a foolish and dangerous practice.
I had a number of 240V shocks from ill-advised experimentation with electricity as a child and young teen, usually to the hand or fingers while seated or kneeling on carpet or vinyl tiles. None of them was particularly painful and no injury resulted, other than minor skin damage at the contact point. In fact I have experienced more discomfort from static shocks than I did from coming in contact with mains voltage.
If he felt anything at all, even a slight tingle, then there was a circuit – although one with a high resistance in it somewhere.
Socks on carpet is, presumably, slightly conductive, allowing a trickle of electrons to squeak through.
Testing a circuit by sticking you finger in the socket seems awfully redundant. Just skip that step and get on with your work; if it’s live, any witnesses in the room with you will know it soon enough.
Knowing there’s no power in the wires you’re working with isn’t expensive. A non-contact voltage tester eliminates guesswork. Check an outlet you know is hot to make sure the tester is working, then check the box you’re messing with.
Well the school probably washed the floor more frequently and with stronger cleaners, and that kept the concrete filled with salt… so a damp salty concrete floor was a good enough conductor to earth.
No body teaches anyone to use their finger to test for a current. The idea may be that the muscles in the finger will contract when shocked … but its not clear or “for sure” that results in the finger disconencting from the conductor… There’s all sorts of reasons why it won’t, but of course its an explanation from why people survive touching conductors, the muscles whip the figner away quite fast …
The safer way to test would be to put a piece of metal in and test for sparks.
It would then only sent molten metal into his eye, if it was live. There are of course commercially available testers… Some work on the principle of earth leakage… its a probe with a light, and you just touch the sharp probe to one conductor… the tiny current to illuminate the light flows through your body to earth, leaking somehow, and it works even on the dryest non-conductive surface…
This guy had probably be an electrician for 20 years or more. He will have been shocked accidentally many times and would have little fear of them. He was also lazy.
So, standing on a chair (too lazy to fetch a ladder?) he doesn’t want to short a live circuit (more work - replacing a fuse wire) and he doesn’t have a circuit tester in his pocket. As far as he was concerned, the simplest and easiest thing to do was to use a finger.
The gun analogy would work better if you just (say) pointed it at the ceiling and pulled the trigger. You could do that hundreds of times before a, it was actually loaded and b, the bullet went through and killed the baby in the cot upstairs.