Lately I had a problem with a hotplate were it kept blowing fuses/tripping the circuit breaker when plugged in but testing the circuit with a multimeter showed no problems.
I eventually narrowed it down to the heating elements, but the resistance was around what it should have been. I figured the insulation was compromised, but not enough to cause problems at the low voltage from the multimeter. I also hooked it up to the bench supply but again it worked fine cranked up to 30V.
Not having a safe way to test at 240V I searched ebay for a cheap insulation tester and with the BM500A at under $20, I figured it would be worth a shot. Didn't need it in the end, as some less than gentle probing cause the insulation to fail completely, making the fault location obvious.
However, checking the specs of the BM500A, I noticed it has a resolution of 1 Kohm. Some of the other (afforadable) testers are higher - 100K or even >1 Megaohm. So how do you use these to test for a short circuit, were the resistance under normal conditions is a few hundred ohms?