Comment on Will my sewing machine upgrade kill me?
Fifrok@discuss.tchncs.de 2 months ago
I would say you’re right about it being just parasitic/capacitive current. And 4.1 uA and 43uA is thousands of times smaller than what would be dangerous, so that’s a no for the kill you part. If you’re very woried about the reading, you could add a 10k-100k Ohm resistor between the machine body and the ground while measuring, if voltage drops to near zero it’s fine.
If you decide to add a ground, please don’t do it with a second plug. Replace the cord with a 3-core one, attach PE to both the machine body and motor.
What would speak against the second plug solution (besides it beeing anoying)?
Fifrok@discuss.tchncs.de 2 months ago
It’s just safer, makes it impossible for the chassis to be un-grounded while the machine is powered. Doesn’t really matter if you’re the only one using the machine and trust yourself to always remember to check if it’s pluged in.
I think this is rather unlikely to happen, but I should mention it:
There’s also some potential to create objectionable current, since neutral is already bonded to earth. And if the PE is pluged into a into a different outlet (or somehow else has a diffrent path to earth), you create parallel paths. There would be small diffreneces between those paths in resistance (and voltage). That means a tiny current can circulate between them, instead of going through the intended ground path.
Those currents should be small, simillar to what you already measured, but they create unpredictability (edit: worded this wrong, they don’t create unpredictability but rather are a sign of it, the unpredictability is caused by the closed loop to ground). If a real fault happens it could make the fault current split changing how a breaker responds. Also, if you have audio equipment, and the objectionable current path goes through it’s ground path you could get some noise/humming