6 ms·

When I was young and stupid, I did this. Suddenly felt some tingling sensation in my fingers, threw the leads away and jumped back. Most certainly saved my life

When I was young and stupid, I did this. Suddenly felt some tingling sensation in my fingers, threw the leads away and jumped back. Most certainly saved my life and drilled in my head how dangerous it is. Still get a sinking feeling in my stomach whenever I am at some switching station below the 380KV leads, remembering that day. Especially after knowing people who got into 120KV, and what happened to them... Electricity is dangerous. In every form. Period. Keep your fingers away from it when you don't know what you do. Household appliances can not only kill you on the mains side. Microwave transformers, flyback circuits, burner igniters, HV Car Ignition Systems...

toxik 4y ago
And remember that RCDs or GFCIs are not the panacea they may seem like at first. All it takes is an unreferenced secondary and voila, ground faults are invisible.
- hattmall 4y ago
  Can you explain what you mean by unreferenced secondary in this context?
  - jeshin 4y ago
    a galvanically isolated transformer, i.e. a voltage that is not referenced to ground, meaning an RCD/GFCI will not be able to trigger if you touch it and it starts zapping you
fendy3002 4y ago
Such as a gun is always loaded, my take is electricity is always dangerous. Even professionals can get into accidents, moreover us uneducated plebs.
- ChrisMarshallNY 4y ago
  I remember watching some electricians rewiring some stuff at my old workplace. We were moving into a new office, and had to have some light switches changed for the new zone. The electrician popped open the switch plates, yanked out the old switches, clipped the wires, stripped the wires, wired up the new switches, and screwed everything back together. It was all live (like 300 volt live), as the lights turned on (queue spark), as he wired the new switches. He was not wearing gloves. It was all barehanded. It was quick, though. Took, like, a minute.
  - mikestew 4y ago
    It obviously can be done, and I've heard folks more experienced than I say "all ya gotta do...", and I'll admit that I might have even wired a switch/outlet myself without flipping the breaker. And a pro could probably get away with it for a long time. But it just sounds like something that is one distraction away from a bad day.
    - aaronmdjones 4y ago
      In the UK, as far as the Health & Safety Executive goes, who are the people who will be hauling you up in court if your screwups cause injury or death, they go to great lengths to discourage working live if at all possible. That said, it is sometimes necessary. I've replaced a circuit protective device in a live electrical panel in a commercial setting before. As you point out, avoiding distraction is a very important factor. That means no chit-chat, no-one overlooking and critiquing what you're doing, noise to a minimum, all of the tools you'll need prepared up-front, etc.
  - foobarian 4y ago
    Meh, for 120V or 220V worst can happen is you get a little shock or trip the breakers. I don't bother shutting off power to household circuits either. I heard from HV vets that one acquires a habit of keeping one hand in the back pocket when working on substations, industrial installations, and such. :-) Not sure where there would be 300V for light switches/fixtures though. Some bespoke factory setup?
- jimnotgym 4y ago
  Every electrician I have met, has had some kind of shock in their career. Mostly it is a small induced current issue, which can easily kill you if it knocks you off a ladder....
  - fendy3002 4y ago
    No matter how many times I see someone changing computer parts while the power is still connected, if I'm doing it I always unplug the power then pressing the power button to ensure it's unpowered
    - aaronmdjones 4y ago
      You won't get hurt working on a live computer unless your power supply is dangerously engineered (stick to well known named brands) or wide open (don't open it up unless it's been unplugged and sitting on a shelf for months) for the same reasons pointed out elsewhere in these comments; the voltage simply isn't high enough. It won't even induce a perceptible amount of current (unless you do something stupid like stick your tongue on it), much less a harmful amount. You'd be surprised at all the stuff you can get away with on a live computer. For example, did you know that AHCI (SATA) and PCIe (and thus NVMe) are both hot-pluggable and hot-swappable? ... and that you can hotswap RAM (with a cooperating motherboard and OS) and even CPUs (on multi-socket boards)?
      - fendy3002 4y ago
        Hdd or ssd are hot swappable? thats cool, thanks for sharing. as for ram I have tried it once and it freeze the pc, I forgot if I have another plugged in or not though.
        SV_BubbleTime 4y ago
        Sata is hotswappable. IDE was not. And I believe m.2 would be if the connector was designed a little different, because that’s all u.2 is. Compact Flash Express is, but again, that’s NVMe and splitting hairs between u.2. Typically on hot swappable devices it’s been common to make the ground pins a little longer than the rest, ensuring that those will make contact first. The issue with hot swappable devices aside from a sharp initial draw is “grounding” the circuit to an IO pin before real ground is made. Most default low potential IO pins won’t enjoy taking the full load of the device while the ground plane is missing connection. Oddly to me, many new PC BIOS ship with SATA hot swapping disabled. IDK why. You can plug the drive in it’ll spin up, but no data transfer will happen until you reboot. Safe, just ineffective. I recently had to learn this the hard way.
HideousKojima 4y ago
I had one the other week where I was replacing an outlet in the kitchen. I flipped the kitchen breaker and the lights and appliances all turned off. I skipped the important step of actually testing the outlet and stupidly assumed it no longer had power. Turns out it was on a different circuit from the rest of the kitchen. The outlet was stuck in the wall box so I reached a flathead screwdriver in to try and pry it out, and turned my screwdriver into an arc welder for a second. Fortunately I wasn't hurt and only got a melted screwdriver tip and a smoky smell out of it, but I'm definitely not going to let myself make that mistake ever again.
- reportingsjr 4y ago
  I made the mistake of not testing _all_ of the wires in an outlet a couple of months ago. I used a non contact voltmeter, and had shut off the breaker to the outlet I was working on. Little did I know that the jackass that did some previous wiring in the house had run wires from a different breaker in to this box. It was done in such a way that I didn't fully realize it could have separate live. My palm below my thumb touched the live and neutral and gave me a pretty solid shock. I'll definitely test every single freaking wire in a box from now on. F people who try to play electrician without knowing what they are doing!
  - jimnotgym 4y ago
    I saw an electrician who did know what he was doing change a fuse board incorrectly. He accidentally swapped one end of two different ring mains so that they were in different breakers! Same result as yours. Always test every live wire. Those glowing voltage sniffer screwdrivers can be pretty handy.
  - ChoGGi 4y ago
    It isn't against code to have different lines inside one box (at least at any of the places I've lived). Easiest way is to flip the mains everytime. I wouldn't trust those pencil testers though (the non-contact ones, the light ones yes).
  - dr_orpheus 4y ago
cge 4y ago
>Electricity is dangerous. In every form. Period. Keep your fingers away from it when you don't know what you do An additional problem here is that the risks are different in different forms. Here, it sounds like people are approaching the technique based on their experiences and assumptions about mains electricity, or even car batteries. 2 kV is high enough voltage that arcing is a risk. Things they'll assume are insulators and safe, or even usable as protection, may be conductive through dielectric breakdown: in the case of wood, that's the whole point of the technique. Even air won't necessarily be safe if they're handling things so closely, especially if it's humid, in which case they could get breakdown at well over 1 mm. Meanwhile, GFCI/RCD is useless, because of the transformer.
gravypod 4y ago
> Still get a sinking feeling in my stomach whenever I am at some switching station below the 380KV leads If you would like to get into the psychology of someone like this I am a big fan of watching photonic induction: https://www.youtube.com/user/Photonvids https://www.youtube.com/user/Photonvids He is, seemingly, a power company tech from the UK who just really loves high voltage and messes with it in his home with his buddy.
thedanbob 4y ago
I had a similar experience in completely different circumstances. I was hiking in the mountains with my dad and some friends when a storm cloud rolled over us. It wasn't raining yet, but one of us noticed that if he raised a metal hiking pole above his head there was a tingling feeling. We all were trying it when my dad caught up and said "what are you doing you idiots, drop those poles, crouch down, and start praying". Thankfully there were no strikes, and after a couple of minutes the cloud had passed. Electricity is dangerous!
eqvinox 4y ago
> Electricity is dangerous. In every form. Well — so is an empty room, because there is no air to breathe. Pretty much everything is dangerous in some form. You can die from excessive water ingestion. You can die falling from a bicycle. I don't think blanket statements like yours are helpful in actually making things safer. Safety low-voltage electrical systems are designed to be safe - not perfectly safe, but comparably safe to other ambient risks of life. We can't bubble-wrap everything. There is no 100%, only a question of how many nines you want after the dot on 99%. But regardless, the videos at issue are quite obviously not in the "99% safe" category and YouTube's behavior is egregiously inacceptable.

toxik 4y ago

And remember that RCDs or GFCIs are not the panacea they may seem like at first. All it takes is an unreferenced secondary and voila, ground faults are invisible.

hattmall 4y ago
Can you explain what you mean by unreferenced secondary in this context?
- jeshin 4y ago
  a galvanically isolated transformer, i.e. a voltage that is not referenced to ground, meaning an RCD/GFCI will not be able to trigger if you touch it and it starts zapping you

fendy3002 4y ago

Such as a gun is always loaded, my take is electricity is always dangerous. Even professionals can get into accidents, moreover us uneducated plebs.

ChrisMarshallNY 4y ago
I remember watching some electricians rewiring some stuff at my old workplace. We were moving into a new office, and had to have some light switches changed for the new zone. The electrician popped open the switch plates, yanked out the old switches, clipped the wires, stripped the wires, wired up the new switches, and screwed everything back together. It was all live (like 300 volt live), as the lights turned on (queue spark), as he wired the new switches. He was not wearing gloves. It was all barehanded. It was quick, though. Took, like, a minute.
- mikestew 4y ago
  It obviously can be done, and I've heard folks more experienced than I say "all ya gotta do...", and I'll admit that I might have even wired a switch/outlet myself without flipping the breaker. And a pro could probably get away with it for a long time. But it just sounds like something that is one distraction away from a bad day.
  - aaronmdjones 4y ago
    In the UK, as far as the Health & Safety Executive goes, who are the people who will be hauling you up in court if your screwups cause injury or death, they go to great lengths to discourage working live if at all possible. That said, it is sometimes necessary. I've replaced a circuit protective device in a live electrical panel in a commercial setting before. As you point out, avoiding distraction is a very important factor. That means no chit-chat, no-one overlooking and critiquing what you're doing, noise to a minimum, all of the tools you'll need prepared up-front, etc.
- foobarian 4y ago
  Meh, for 120V or 220V worst can happen is you get a little shock or trip the breakers. I don't bother shutting off power to household circuits either. I heard from HV vets that one acquires a habit of keeping one hand in the back pocket when working on substations, industrial installations, and such. :-) Not sure where there would be 300V for light switches/fixtures though. Some bespoke factory setup?
jimnotgym 4y ago
Every electrician I have met, has had some kind of shock in their career. Mostly it is a small induced current issue, which can easily kill you if it knocks you off a ladder....
- fendy3002 4y ago
  No matter how many times I see someone changing computer parts while the power is still connected, if I'm doing it I always unplug the power then pressing the power button to ensure it's unpowered
  - aaronmdjones 4y ago
    You won't get hurt working on a live computer unless your power supply is dangerously engineered (stick to well known named brands) or wide open (don't open it up unless it's been unplugged and sitting on a shelf for months) for the same reasons pointed out elsewhere in these comments; the voltage simply isn't high enough. It won't even induce a perceptible amount of current (unless you do something stupid like stick your tongue on it), much less a harmful amount. You'd be surprised at all the stuff you can get away with on a live computer. For example, did you know that AHCI (SATA) and PCIe (and thus NVMe) are both hot-pluggable and hot-swappable? ... and that you can hotswap RAM (with a cooperating motherboard and OS) and even CPUs (on multi-socket boards)?
    - fendy3002 4y ago
      Hdd or ssd are hot swappable? thats cool, thanks for sharing. as for ram I have tried it once and it freeze the pc, I forgot if I have another plugged in or not though.
      - SV_BubbleTime 4y ago
        Sata is hotswappable. IDE was not. And I believe m.2 would be if the connector was designed a little different, because that’s all u.2 is. Compact Flash Express is, but again, that’s NVMe and splitting hairs between u.2. Typically on hot swappable devices it’s been common to make the ground pins a little longer than the rest, ensuring that those will make contact first. The issue with hot swappable devices aside from a sharp initial draw is “grounding” the circuit to an IO pin before real ground is made. Most default low potential IO pins won’t enjoy taking the full load of the device while the ground plane is missing connection. Oddly to me, many new PC BIOS ship with SATA hot swapping disabled. IDK why. You can plug the drive in it’ll spin up, but no data transfer will happen until you reboot. Safe, just ineffective. I recently had to learn this the hard way.

HideousKojima 4y ago

I had one the other week where I was replacing an outlet in the kitchen. I flipped the kitchen breaker and the lights and appliances all turned off. I skipped the important step of actually testing the outlet and stupidly assumed it no longer had power. Turns out it was on a different circuit from the rest of the kitchen. The outlet was stuck in the wall box so I reached a flathead screwdriver in to try and pry it out, and turned my screwdriver into an arc welder for a second. Fortunately I wasn't hurt and only got a melted screwdriver tip and a smoky smell out of it, but I'm definitely not going to let myself make that mistake ever again.

reportingsjr 4y ago
I made the mistake of not testing _all_ of the wires in an outlet a couple of months ago. I used a non contact voltmeter, and had shut off the breaker to the outlet I was working on. Little did I know that the jackass that did some previous wiring in the house had run wires from a different breaker in to this box. It was done in such a way that I didn't fully realize it could have separate live. My palm below my thumb touched the live and neutral and gave me a pretty solid shock. I'll definitely test every single freaking wire in a box from now on. F people who try to play electrician without knowing what they are doing!
- jimnotgym 4y ago
  I saw an electrician who did know what he was doing change a fuse board incorrectly. He accidentally swapped one end of two different ring mains so that they were in different breakers! Same result as yours. Always test every live wire. Those glowing voltage sniffer screwdrivers can be pretty handy.
- ChoGGi 4y ago
  It isn't against code to have different lines inside one box (at least at any of the places I've lived). Easiest way is to flip the mains everytime. I wouldn't trust those pencil testers though (the non-contact ones, the light ones yes).
- dr_orpheus 4y ago

cge 4y ago

>Electricity is dangerous. In every form. Period. Keep your fingers away from it when you don't know what you do An additional problem here is that the risks are different in different forms. Here, it sounds like people are approaching the technique based on their experiences and assumptions about mains electricity, or even car batteries. 2 kV is high enough voltage that arcing is a risk. Things they'll assume are insulators and safe, or even usable as protection, may be conductive through dielectric breakdown: in the case of wood, that's the whole point of the technique. Even air won't necessarily be safe if they're handling things so closely, especially if it's humid, in which case they could get breakdown at well over 1 mm. Meanwhile, GFCI/RCD is useless, because of the transformer.

gravypod 4y ago

> Still get a sinking feeling in my stomach whenever I am at some switching station below the 380KV leads If you would like to get into the psychology of someone like this I am a big fan of watching photonic induction: https://www.youtube.com/user/Photonvids https://www.youtube.com/user/Photonvids He is, seemingly, a power company tech from the UK who just really loves high voltage and messes with it in his home with his buddy.

thedanbob 4y ago

I had a similar experience in completely different circumstances. I was hiking in the mountains with my dad and some friends when a storm cloud rolled over us. It wasn't raining yet, but one of us noticed that if he raised a metal hiking pole above his head there was a tingling feeling. We all were trying it when my dad caught up and said "what are you doing you idiots, drop those poles, crouch down, and start praying". Thankfully there were no strikes, and after a couple of minutes the cloud had passed. Electricity is dangerous!

eqvinox 4y ago

> Electricity is dangerous. In every form. Well — so is an empty room, because there is no air to breathe. Pretty much everything is dangerous in some form. You can die from excessive water ingestion. You can die falling from a bicycle. I don't think blanket statements like yours are helpful in actually making things safer. Safety low-voltage electrical systems are designed to be safe - not perfectly safe, but comparably safe to other ambient risks of life. We can't bubble-wrap everything. There is no 100%, only a question of how many nines you want after the dot on 99%. But regardless, the videos at issue are quite obviously not in the "99% safe" category and YouTube's behavior is egregiously inacceptable.