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I have a laptop, which comes with an SMPS charger. The laptop charger is a very common type. I know there are some earthing issues in my home. I need to fix that. But SMPS isolate mains from the supply, but when I touch the body of the laptop, it shocks. Another day, I was charging my phone through USB from the laptop and plugged the laptop charger. I own a metal earphone, and that shocked me. I know there's some problem in my home earthing part, but still aren't SMPS meant to be isolated from mains. Then why I'm getting that shock. Why does electricity want to flow through my body if it's floating? Someone, please explain the incident, with reasoning and possible ways to avoid it.

SOUHARDHYA PAUL
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  • If the laptop power supply has an earthed mains plug, it must be connected to earthed mains socket due to the EMI filter in it can cause the laptop ground to float at half the mains. If the laptop power supply has an unearthed mains plug, it still has an EMI filter cap inside it that will couple some of the mains voltage to the output (why on earth they make these anyway). Which kind of mains plug your laptop has and to which kind of mains socket it is connected to? – Justme Feb 20 '21 at 21:30
  • Most of these adapters have a Y-capacitor between primary and secondary side for common-mode noise attenuation. Depending on the capacitor value and the mains frequency, this current can be significant and you may feel it in certain conditions. At the time cell-phones had a metal plate, users felt the current on their cheek (it was the shaver effect) and many manufacturers imposed adapters without a Y-cap. In your case, it can be the Y-cap current (but it should not shock you!) or there is leakage and the adapter is faulty. If the earth is defective in your case, it could also be the issue. – Verbal Kint Feb 20 '21 at 21:31
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    Are you an earthling? Check your question title. – Transistor Feb 20 '21 at 21:36
  • it's not a `SMPS charger` ... it is a `SMPS power supply` ... the battery charger is inside the laptop – jsotola Feb 21 '21 at 01:30
  • Is your earth connection actually earth or is it connected to the neutral or worse yet not connected. You are describing your house wiring as a fire hazard, It should be checked by a qualified electrician. These types of things can be fatal, and we want to keep you around. – Gil Feb 21 '21 at 03:29

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