bathroom anti mist mirror with leds

If you can feel a shock then there could be something very wrong - so be careful.


I would normally expect LED systems - especially in a bathroom - to be SELV - so earthing of that side should be neither necessary or indeed desireable (earthing things introduces a potential path for a shock current to earth so is better avoided where possible).


The anti-mist header might be mains powered though - I'd hope it was protected by double/reinforced insuation, but an earthed system could be possible. It could be that that's giving the problem.


The reading with a digital meter isn't particularly conclusive - such meters can show readings up to a significant fraction of mains voltage without there being a real problem if there is a large impedance in the path somewhere. The typical explanation is capacitive coupling where bits of metal can pick up a significant voltage from nearby insulated conductors (say a de-misting pad) but the current that could flow in such circumstances is far too low (fractions of a mA) to pose any kind of shock hazard. In this case if a shock has been felt there could be more going on - but at this stage it's hard to tell whether the meter reading is a red flag or just a red herring.


What was being touched when the shock was felt? For a current to flow though someone it normally need to flow both into and out of someone's body - i.e. you need at least two points of contact - so what else was being touched at the same time? There's always the possibility that the 'other thing' had some dangerous voltage on it and the mirror was the innocent party just providing a path back to earth (or N). You can get very odd effects like this when most or all of the entire installation isn't correctly earthed - most things are hovvering around at a hazardous voltage but people notice shocks when they touch things that are actually earthed. I'm presuming the shock was the "buzz" or "tingle" of a mains shock, rather than the "pin-prick" of a shock from static electricity.


  - Andy.

If you can feel a shock then there could be something very wrong - so be careful.


I would normally expect LED systems - especially in a bathroom - to be SELV - so earthing of that side should be neither necessary or indeed desireable (earthing things introduces a potential path for a shock current to earth so is better avoided where possible).


The anti-mist header might be mains powered though - I'd hope it was protected by double/reinforced insuation, but an earthed system could be possible. It could be that that's giving the problem.


The reading with a digital meter isn't particularly conclusive - such meters can show readings up to a significant fraction of mains voltage without there being a real problem if there is a large impedance in the path somewhere. The typical explanation is capacitive coupling where bits of metal can pick up a significant voltage from nearby insulated conductors (say a de-misting pad) but the current that could flow in such circumstances is far too low (fractions of a mA) to pose any kind of shock hazard. In this case if a shock has been felt there could be more going on - but at this stage it's hard to tell whether the meter reading is a red flag or just a red herring.


What was being touched when the shock was felt? For a current to flow though someone it normally need to flow both into and out of someone's body - i.e. you need at least two points of contact - so what else was being touched at the same time? There's always the possibility that the 'other thing' had some dangerous voltage on it and the mirror was the innocent party just providing a path back to earth (or N). You can get very odd effects like this when most or all of the entire installation isn't correctly earthed - most things are hovvering around at a hazardous voltage but people notice shocks when they touch things that are actually earthed. I'm presuming the shock was the "buzz" or "tingle" of a mains shock, rather than the "pin-prick" of a shock from static electricity.


  - Andy.