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I've noticed that even with an earthed power supply I still have the problem with the newer USB-C MacBooks. I find it rather uncomfortable on my wrists. A MacB

by mjlee 8y ago

I've noticed that even with an earthed power supply I still have the problem with the newer USB-C MacBooks. I find it rather uncomfortable on my wrists. A MacBook I had quite a few years ago had a cracked chassis - touching that when using a non-earthed power supply was enough to be a little bit painful.

howard941 8y ago
I have the same problem with a bog-standard Dell laptop power supply. The safety ground (earth) lead is bonded to neutral way the hell back at the meter so there's too much inductance in the lead and through the whole house to do much good other than prevent electrocution.
- fb03 8y ago
  Can't you simply unplug this connection and install a proper earth at your place? That's what I did (literally: huge copper bar buried) and a lot of stuff (including the shower, which in my country is electrically heated) stopped giving me tingles.
  - howard941 8y ago
    There's an 8 foot long copper rod as the earth ground now. Replacing the existing connection would be nasty, the power company would have to come out to pull the meter (it's sealed) to get at the bonding strap inside the box and it's doubtful they'd reenergize the place without a visible bond.
  - mises 8y ago
    That sounds smart, though I can't imagine a huge copper bar came cheap. You can get something for as little as $17 off Amazon, and maybe cheaper if you look harder: https://www.amazon.com/Skywalker-Signature-Ground-Rod-4ft/dp/B009OMMRMO/ https://www.amazon.com/Skywalker-Signature-Ground-Rod-4ft/dp...
    - mindslight 8y ago
      Grounding rods are generally copper clad steel. In the US, proper ones are 8ft. $13 at Home Depot. An electrician can either measure the actual impedance or put in two rods with some spacing, so they're often just used in pairs. Back when Radio Shack was closing I put the damper on some guy who was going to buy all the grounding rods thinking he'd scrap the copper. I did him the favor of disappointing him before he spent his money.
    - nielsbjerg 8y ago
      Does not have to be copper. I've done several of these using galvanized steel hammered into the ground. We'd hammer in rods of 2 meters length until the resistance was low enough (around 1600 ohms Iirc). This would ensure hpfi tripped below 50mA
  - sandworm101 8y ago
    Be very careful about this. Grounding isn't always as easy as hammering in a spike. Some soils don't conduct properly, something that can change throughout the year as water tables move. A few US soldiers in Iraq were wounded in showers because while the electrical system was not properly ground, the shower drains were.
    - balabaster 8y ago
      We used to frequently have problems with the electric fences on our farm for this same reason. Once every few weeks I pour a 5 gallon pail of water over the grounding rod to keep the fence at 7,000V. Works like a charm. This is particularly problematic where soil is a shale/gravel mix and drains quickly leaving little moisture. Grounding requires moisture for maximum conductivity. Good grounding is also required to complete the electrical circuit when you touch the fence.
      - Scoundreller 8y ago
        Salty water (or acidic, or basic water) would be even more conductive, no? And the salt would reduce evaporation (and remain until it rains) until next time. Would probably kill any crops, which will help retain even more moisture.
        balabaster 8y ago
        I hadn't considered this, but yes, now that you mention it, given that salt water is more conductive, it would perhaps be more effective. My fences appear to provide maximum output (on a standard livestock electric fence tester) with our regular well water, so it hadn't occurred to me to give this any further thought.
        coryrc 8y ago
        There are already sufficients ions in the soil to conduct well.
        Scoundreller 8y ago
- abakker 8y ago
  Have you actually checked the ground for continuity? IN my house, I found that many of the upstairs outlets (wired with BX) had their grounds bonded to the water pipes in my house, instead of run directly to the box, and then the water pipe was bonded to the box down near the service entrance. Unfortunately, there was no ground continuity because at some point a pipe segment had been replaced with PVC instead of copper and the continuity ended. Bonding grounds to pipes was very common in older houses and is a common source of bad ground loops and electrical noise.
  - sandworm101 8y ago
    >> a pipe segment had been replaced with PVC instead of copper Which is why when you do that you are supposed to always install a wire to jump over the now non-conductive section of pipe.
    - abakker 8y ago
      Exactly what I did. I’m not sure the original homeowner knew that it mattered. I first noticed the issue with a stepper motor project I was working on. It was very interesting to hear the reduction in audible noise from the motors when the grounding was fixed.
    - atesti 8y ago
      Also if current runs over pipes, there might be more corrosion when different kinds of metal meet. You should never run ground over pipes, but instead use a dedicated copper wire
  - fastaguy88 8y ago
    This is a true story. One night, I went down into my basement and heard a snapping sound, and looked to see sparking between a 12-14G copper ground wire (from somewhere) and my water supply pipe. It turns out that my 1952-build house did NOT have a ground/earth for the panel, and a squirrel had chewed all but the last few strands of the neutral coming from the power pole. Most of the return from the house was going through this piddly ground strap, and it was not happy. I called the power company, and they were kind enough to install an new neutral almost immediately (perhaps at night). I then called an electrician, who grounded my panel. I am still amazed that my refrigerators and ovens worked, and wonder what would have happened if I had not heard the snapping sound.
- rini17 8y ago
  This is the standard everywhere in Europe, with separated earth and neutral wires which are connected and grounded somewhere farther. It is done for a purpose and not a problem when done properly. The resistance nor inductance is never enough to allow so high potential, even at kHz frequencies of switching power supplies. So this indicates a problem on earth wire that should be fixed by a professional, not by blindly adding some makeshift earthing.
  - shawnz 8y ago
    It's the standard in North America too, neutral and ground are bonded at the panel and can't be connected anywhere closer than that (which would be referred to as a 'bootleg ground' and could create electrocution risks if the wiring is wrong)
jakejarvis 8y ago
Same for the back of my iPad Pro at times, too. I appreciate this post – thought I was crazy!
krisrm 8y ago
Mildly off-topic: is "earthed" a European-ism? I've only ever heard "grounded" until reading through this article and thread.
- soneil 8y ago
  British English - the author is Australian.
- sonofgod 8y ago
  It's certainly British English.
- magduf 8y ago
  >Mildly off-topic: is "earthed" a European-ism? Yes. We say "grounded" in the US English, but in UK English it's usually called "earthed".
  - dylan604 8y ago
    Grounded means no tv or video games for 2 weeks. I’ve done enough reading for electrical wiring for both small electronics and electrical power that I’ve seen both terms frequently enough that neither seems out of place to me.
- Sujan 8y ago
  Maybe also a translation thing, in German "grounding" is translated to "erden" which means "putting into or connecting to the ground", but "Erde" is also the substantive meaning "earth".
  - gowld 8y ago
    Words take on a range of meaning. "ground" and "earth" have overlapping meanings.
    - iforgotpassword 8y ago
      Sure. In English though it's fine to refer to e.g. the street as "ground", like when you drop your ice cream outside. In German, "Grund" would be something like the ground of a lake, your ice cream would drop on the "Erde". So they have the same meaning but in the overlapping area English is biased towards ground and German towards earth. Or something like that.

by mjlee 8y ago

howard941 8y ago

I have the same problem with a bog-standard Dell laptop power supply. The safety ground (earth) lead is bonded to neutral way the hell back at the meter so there's too much inductance in the lead and through the whole house to do much good other than prevent electrocution.

fb03 8y ago
Can't you simply unplug this connection and install a proper earth at your place? That's what I did (literally: huge copper bar buried) and a lot of stuff (including the shower, which in my country is electrically heated) stopped giving me tingles.
- howard941 8y ago
  There's an 8 foot long copper rod as the earth ground now. Replacing the existing connection would be nasty, the power company would have to come out to pull the meter (it's sealed) to get at the bonding strap inside the box and it's doubtful they'd reenergize the place without a visible bond.
- mises 8y ago
  That sounds smart, though I can't imagine a huge copper bar came cheap. You can get something for as little as $17 off Amazon, and maybe cheaper if you look harder: https://www.amazon.com/Skywalker-Signature-Ground-Rod-4ft/dp/B009OMMRMO/ https://www.amazon.com/Skywalker-Signature-Ground-Rod-4ft/dp...
  - mindslight 8y ago
    Grounding rods are generally copper clad steel. In the US, proper ones are 8ft. $13 at Home Depot. An electrician can either measure the actual impedance or put in two rods with some spacing, so they're often just used in pairs. Back when Radio Shack was closing I put the damper on some guy who was going to buy all the grounding rods thinking he'd scrap the copper. I did him the favor of disappointing him before he spent his money.
  - nielsbjerg 8y ago
    Does not have to be copper. I've done several of these using galvanized steel hammered into the ground. We'd hammer in rods of 2 meters length until the resistance was low enough (around 1600 ohms Iirc). This would ensure hpfi tripped below 50mA
- sandworm101 8y ago
  Be very careful about this. Grounding isn't always as easy as hammering in a spike. Some soils don't conduct properly, something that can change throughout the year as water tables move. A few US soldiers in Iraq were wounded in showers because while the electrical system was not properly ground, the shower drains were.
  - balabaster 8y ago
    We used to frequently have problems with the electric fences on our farm for this same reason. Once every few weeks I pour a 5 gallon pail of water over the grounding rod to keep the fence at 7,000V. Works like a charm. This is particularly problematic where soil is a shale/gravel mix and drains quickly leaving little moisture. Grounding requires moisture for maximum conductivity. Good grounding is also required to complete the electrical circuit when you touch the fence.
    - Scoundreller 8y ago
      Salty water (or acidic, or basic water) would be even more conductive, no? And the salt would reduce evaporation (and remain until it rains) until next time. Would probably kill any crops, which will help retain even more moisture.
      - balabaster 8y ago
        I hadn't considered this, but yes, now that you mention it, given that salt water is more conductive, it would perhaps be more effective. My fences appear to provide maximum output (on a standard livestock electric fence tester) with our regular well water, so it hadn't occurred to me to give this any further thought.
      - coryrc 8y ago
        There are already sufficients ions in the soil to conduct well.
        Scoundreller 8y ago
abakker 8y ago
Have you actually checked the ground for continuity? IN my house, I found that many of the upstairs outlets (wired with BX) had their grounds bonded to the water pipes in my house, instead of run directly to the box, and then the water pipe was bonded to the box down near the service entrance. Unfortunately, there was no ground continuity because at some point a pipe segment had been replaced with PVC instead of copper and the continuity ended. Bonding grounds to pipes was very common in older houses and is a common source of bad ground loops and electrical noise.
- sandworm101 8y ago
  >> a pipe segment had been replaced with PVC instead of copper Which is why when you do that you are supposed to always install a wire to jump over the now non-conductive section of pipe.
  - abakker 8y ago
    Exactly what I did. I’m not sure the original homeowner knew that it mattered. I first noticed the issue with a stepper motor project I was working on. It was very interesting to hear the reduction in audible noise from the motors when the grounding was fixed.
  - atesti 8y ago
    Also if current runs over pipes, there might be more corrosion when different kinds of metal meet. You should never run ground over pipes, but instead use a dedicated copper wire
- fastaguy88 8y ago
  This is a true story. One night, I went down into my basement and heard a snapping sound, and looked to see sparking between a 12-14G copper ground wire (from somewhere) and my water supply pipe. It turns out that my 1952-build house did NOT have a ground/earth for the panel, and a squirrel had chewed all but the last few strands of the neutral coming from the power pole. Most of the return from the house was going through this piddly ground strap, and it was not happy. I called the power company, and they were kind enough to install an new neutral almost immediately (perhaps at night). I then called an electrician, who grounded my panel. I am still amazed that my refrigerators and ovens worked, and wonder what would have happened if I had not heard the snapping sound.
rini17 8y ago
This is the standard everywhere in Europe, with separated earth and neutral wires which are connected and grounded somewhere farther. It is done for a purpose and not a problem when done properly. The resistance nor inductance is never enough to allow so high potential, even at kHz frequencies of switching power supplies. So this indicates a problem on earth wire that should be fixed by a professional, not by blindly adding some makeshift earthing.
- shawnz 8y ago
  It's the standard in North America too, neutral and ground are bonded at the panel and can't be connected anywhere closer than that (which would be referred to as a 'bootleg ground' and could create electrocution risks if the wiring is wrong)

jakejarvis 8y ago

Same for the back of my iPad Pro at times, too. I appreciate this post – thought I was crazy!

krisrm 8y ago

Mildly off-topic: is "earthed" a European-ism? I've only ever heard "grounded" until reading through this article and thread.

soneil 8y ago
British English - the author is Australian.
sonofgod 8y ago
It's certainly British English.
magduf 8y ago
>Mildly off-topic: is "earthed" a European-ism? Yes. We say "grounded" in the US English, but in UK English it's usually called "earthed".
- dylan604 8y ago
  Grounded means no tv or video games for 2 weeks. I’ve done enough reading for electrical wiring for both small electronics and electrical power that I’ve seen both terms frequently enough that neither seems out of place to me.
Sujan 8y ago
Maybe also a translation thing, in German "grounding" is translated to "erden" which means "putting into or connecting to the ground", but "Erde" is also the substantive meaning "earth".
- gowld 8y ago
  Words take on a range of meaning. "ground" and "earth" have overlapping meanings.
  - iforgotpassword 8y ago
    Sure. In English though it's fine to refer to e.g. the street as "ground", like when you drop your ice cream outside. In German, "Grund" would be something like the ground of a lake, your ice cream would drop on the "Erde". So they have the same meaning but in the overlapping area English is biased towards ground and German towards earth. Or something like that.