Ball lightning in my workshop!

[Jameel Abraham]

Well, not quite....

I have a 5hp motor on a particular machine that maybe 25% of the time gives a loud pop (an electrical pop) and a bright flash (like a strobe) from the machines cabinet (there's a gap under it so it lights up the floor quite a bit).

The manufacturer had me take the motor apart and clean the contacts in the centrifugal switch.

I'm in the middle of that right now, but it sounds to me (and I'm no motor expert) that the points were slightly apart, and when starting the machine, sometimes they would arc and create the pop and flash. So I'm assuming these points should be contacting each other very nicely in the off postition?

[Steve Leverich]

Yup - those contacts are for the starting capacitor, and should be closed until the motor reaches somewhere over half of run speed... Steve

[Ken Fitzgerald]

Jameel........You ought to see the spark you get on a Cat scanner when one of the high voltage cables gets cut and you bring the high voltage up to 120,000 volts dc and find the cut cable by the arc...in a brightly lit room!

I suspect those contacts should be closed until it's up to speed. Good luck!

[David G Baker]

You should see the sparks when the front end loader on your tractor cuts the under ground power line to your out buildings.
Sounds like a centrifugal switch that may need the contacts cleaned, replaced or adjusted. A little arc is normal but a snap crackle and pop is not.

[Jameel Abraham]

I had to wrestle the motor out (I'm guessing it weighed way over 100lbs) and then when I cleaned and adjusted the switch, and had the whole thing put back together it did it again! But it hasn't done it since. I'm guessing it was a fluke.