So a while ago i got my hands on a old sewing machine sadly the foot pedal blew up on me and i also noticed that the machine made my fingers tingle (more on that in this old post here: https://sh.itjust.works/post/35395330 ).
After that i didnt touch the thing for a while but now i needed to sew something so i got myself a new motor and pedal for it online.
The motor fits neat to the machine and the pedal works. But after the last time i was a bit afraid to just touch it, decided to better do a voltage check first.
So i grabbed a Multi meter and connected one side to main earth, and the other side to the metal body of the machine.
And apparently there are 30-32V AC on the metal body of the machine :( Then i tested the current and it was 4.1uA.
I did the same thing for the motor spindle an and the results where even worse >.< 173V AC on the spindle and 43uA when i short it to main earth over the multi meter.
Now my question is:
Is this normal?
Is it maybe just some parasitic currents from the Motor windings acting as antenna and inducting voltage into the metal body of the machine?
Will it kill me if i touch it?
Should i ground the machine to earth using a second plug?
Should i isolate the motor from the metal machine body?
Here are some more pictures from my measurements and measurement setup:
30V won't kill you. Even with 170V it might not cause much harm, since the current is in micro Amperes. I hope you have a good MCB, and even even good curcuit breakers. If they are present and they don't get tripped while operating or testing, it should not be lethal.
That said, you don't know the reason for this leak. Better to take it a repair shop. If you like doing it yourself open up and see if there is any visible tear on power line insulation. If nothing is visible if can be some issue with winding of motor, some other component.
You can use it with gloves, a good foot wear, and a good set of circuit breakers, if it has to be used, but I won't recommend taking such risks. Since it is an old machine I would say you get it repaired if possible.
Well, it definitely can, in certain circumstances -- if there's enough amperage available and if something (such as having wet hands) reduces the electrical resistance of your skin.
But, yes, with current in the micro-amps even when dead shorted, this shouldn't be too dangerous.
Though, OP feeling a tingling when they touch it gives me pause. 30V shouldn't really do that in most cases. OP is measuring AC voltage here, but maybe there's also a DC voltage on it?