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I have had bilateral shoulder pain and then both arms and hands pain for around 7 mounts, which got much worse when I started working from home, with my laptop. The ultrasound of shoulder muscles revealed tendonitis which means inflammation in tendons. Nothing helped my pain relived, not the physiotherapy, message therapy or even pain killers and voltaren gel. In recent days I accidentally discovered that when I am working with my laptop, and touch its body, it is giving my body a voltage of around 37-40 V (I measure it with a multimeter set on AC V, one pin connected to the ground connection and the other in my hand)Laptop have a two pronged plug and is not grounded. When I checked this with one of my friends, he is getting around only 5-6 volts the same way of measuring on his own, ungrounded laptop. I bought this laptop (Asus Zenbook UX431) about 8 mounts ago, so it can explain the onset of pain in my body as well. My doctor refused to accept this can be a reason for my problems, but I have strong feelings and reason that this can be behind my issues. I wonder if you can also measure the voltage induced in your body while touching your laptop's body and tell what you get? I need more evidence if his can be the source of my problems. I just need some of your measurements and numbers, Thanks so much!

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    \$\begingroup\$ It's probably improper posture made worse by working from home without a properly set up workstation. A static shock is 5kV and higher, 10kV or even 15kV or 30kV. 40V is nothing. \$\endgroup\$
    – DKNguyen
    Apr 2 at 2:49
  • \$\begingroup\$ Thanks for your answer DKNguyen, I don't get a shock when I touch the laptop, so it is apparently not too high, but I suspect because I have been using it for a long time, and long hours, if it is much more than normal it may have caused some inflammations... By the way if you can also measure your body voltage when touching your laptop it may help to understand.. \$\endgroup\$
    – Reza-sh
    Apr 2 at 2:58
  • \$\begingroup\$ Please note that static electricity discharges in microseconds, so not enough time to make a damage! \$\endgroup\$
    – Reza-sh
    Apr 2 at 3:19
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    \$\begingroup\$ Laptops are terrible for tendonitis since they encourage poor posture and straining as you keep your arms unnaturally close together. You should try to minimize your laptop usage as soon as possible. Get a real keyboard and monitor, take regular breaks. That will also stop exposure to leakage current, but that is unlikely to be the problem. Chronic tendon injury can be severe and lifelong. You want to avoid making the problem worse. \$\endgroup\$ Apr 2 at 12:33
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    \$\begingroup\$ I think you are chasing a ghost. It is extremely unlikely that the voltages you see are causing the symptoms you report. As many have said, common ergonomic issues are almost certainly the cause of your pain. I have been there myself. \$\endgroup\$ Apr 2 at 13:00
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The power supply has a certain amount of leakage current. The leakage is coupling through the isolation transformer.

That open-circuit floating voltage you’re seeing is typical and within safety limits for a consumer device. You probably also saw it drop to a low value (a couple of volts or so) when you touched the laptop. That should tell you how weak this current actually is.

The applicable safety standards limit this current to 3mA or so. In most cases this will be lower than that - 1 or 2 mA or so. You can measure that, too, using the mA AC scale on your meter.

That said, you could be sensitive to it. Try using your laptop only off battery and see if that makes a difference. If it doesn’t, it may very well be an ergonomic issue like your doc is probably thinking. If it is, you could try connecting your laptop to a ground.

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  • \$\begingroup\$ Thanks for your answer. By unplugging the laptop the voltage dramatically drops to less than a volt... \$\endgroup\$
    – Reza-sh
    Apr 2 at 3:01
  • \$\begingroup\$ I should also mention that just using the keyboard or trackpad doesn’t expose you to the chassis. So there isn’t a direct path to your body. It’s highly unlikely that you’re a path for the leakage at all. \$\endgroup\$ Apr 2 at 3:20
  • \$\begingroup\$ I used to rest my wrist on the laptop body which is metallic when typing, so directly connected most of the times... \$\endgroup\$
    – Reza-sh
    Apr 2 at 3:33

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