I have seen the light — 11 Comments

  1. Survival tip – never trust any switch, fuse-panel or circuit-breaker. Always carry a circuit-testing screwdriver to confirm that it really is dead before you are.

    • I have bought and lost loads of those phase testers in my time. I can never find one when I need it.

      • Phase testers belong in the bin, a decent voltage probe or multimeter isn’t expensive (less than €20 on some websites)and leads to fewer holes in pliers, stains in underwear or trips to the hospital etc.

      • Same problem here grandad. I solved that by getting yet another one and hanging it on the wall next to the breaker box. Just remember to put it back when you’re done.

  2. A few years ago they were renovating our office and moving walls around. The “electrician” didn’t want to go to the trouble of figuring out which circuit breaker went with which wire. So instead he simply using his diagonal pliers to cut the cable and in the process shorting the conductor to the return and neutral causing the circuit breaker to trip. On the standard US 115 VAC circuits this was working. Then he went to cut a new cable and hear a loud boom, was thrown from the ladder he was on, and came too laying on the ground in the dark with several of us looking down at him. That cable was not 115 VAC, but a three phase 480 VAC going to the shop floor to power heavy machinery. That line also supplied power to about half of the building. He did survive, but was never allowed to work on electrical again.

  3. Anyone not having come down with the last shower would switch on a light or plug something in which is connected to the same MCB or fuse. If it lights or works you have the wrong MCB. Of course I can joke about your near miss but seriously, when I moved in here, knowing that a lot of electrical work was ahead, I went through the MCBs in turn to find out what was connected to each, then marked up the consumer unit accordingly. Know the electrical layout of your house.

    But my point to all this is, if I need to isolate one of those circuits, I still try a light or a drill in a socket to make sure its off, even though its marked up good enough that even a blind person couldn’t get the wrong one. You were lucky GD, my guess is that the ladder provided a quicker/easier route to ground than your body. And I don’t work in slippers or shoes either, thick rubber soled work boots can save you if you inadvertently touch something else whilst working. One thing that’s good to know is, if you have a modern consumer unit the risk of shock is a lot lower, since the RCD trips out at something like 0.03 amps and they are fast. Also you can switch off individual circuits without pulling fuses or switching the lot off. My workshop out back comes off its own MCB via armoured cable to a second consumer unit in the workshop. This keeps the power on in the house if anything happens to knock it off in the workshop.

    Another good tip is, when installing a new circuit, or even one that taps into an existing circuit, install the new circuit first, or if you are replacing one, install the new circuit alongside the old, *then* connect it to the consumer unit last. This will minimize risk during the job and also down time with power off. In other words, measure out what cable you need plus some, connect it to the light, put up the wall bracket, mount the light, thread the cable, switch off the power then connect it up. I have a few mains testing screwdrivers but very rarely use them for anything other than driving screws. I also invested in a rechargeable LED work light that’s been invaluable if you find yourself having to work after dark, and a head light for up the loft.

  4. When I move into a new house I always map out the circuit breakers. Turning them all off and one by one turning on. Testing what is live and then turning off moving to the next till all are mapped where I turn them all on.

    But paranoid sod I am even when I flick the breaker and turn it off I always test with a electrical testing screwdriver as well as treating it as if it is live by only working on one wire at a time to take care.

    I also don’t take peoples word that it is disconnected. People are stupid and you are stupid if you put your life in their hands.

    When I was an apprentice I worked on rewiring a friends house. The mains was supposedly off and I was working on my bit of the circuit. All was going well and then someone came in looked at what I was wiring and then cut the wire further down. There was a tremendous flash and at that point I discovered I had been working on a live circuit for the last hour. I made sure I never made that mistake again by being a paranoid git. It has shown me how stupid some people are and how careless they are of your life.

    Sounds to me like you had taken more care than you thought when working on the wiring as you imply but there was a lot of luck involved as well.

  5. Many, many years ago, when I was a callow young apprentice, touched a live terminal while I was fault finding a circuit. A fellow apprentice asked me what I had done so, after switching the device off, I showed him. And got another shock because the terminal I touched was on the live side of the switch. 😮

    So now, if I ever have to work on electrical stuff I isolate it then meter it to make sure I’ve isolated it. Once bitten…

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