I work with a guy who checks run capacitors as a part of his routine maintenance. If it is supposed to be 20mfd and his checker say 17mfd he say es it is bad and replaces it.

I know this falls out side the 10% tolerance but my question is, is his checker that accurate?

I have always been taught that on a run capacitor if it is not shorted, open, or grounded it is OK.

I know there are homemade and other line voltage testers that can accurately test for capacitance but a hand held with three volts. I just do not know?

What do you guy think? Does anybody have any factory data on this?

Thanks Steve