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:

  • Mpatch@lemmy.worldEnglish
    2·
    10 days ago

    Okay this is fun. So first of your amp reading is no Bueno. As I can tell you have no real load on the circuit so your amp draw will be low. Until something acts as a load like a light bulb contacting the frame and the neutral line or your hands. So the amp will rise.

    Now the next thing there is power going to the motor, with out the foot pedal engaged?

    A quick hunch makes me say is the new foot pedal wired backwards? On ac circuits it’s you cut power at the switch and the rest of the unit is connected to neutral line all the time.

    Those sowing machine motors are typically “universal motors” they are brushed motors that can run on both ac and DC. So power flows from footpedals to brushes to armature, to windings back out the other brush. It’s a bit on the weird side that the shaft has voltage. It could be from a brush sitting funny maybe. But I would most definitely just check the wiring orientation for starters. Then go from there. Adding a ground connection isn’t a solution. A ground wire is to prevent you from getting hurt when this happens.