Hello,
Installing under cabinet lights and upgrading 30yr old switches and receptacles in the kitchen when something I've never encountered happen.
I have a neon-tester I use to make sure there is no power before doing any work. I'm not sure if this is the official name for it, but it's a very convenient tool I've had for a couple years now. For example, I can hold one metal tip to a live black wire and put the other tip to the neutral white wire and the light at the end of the tester lights up. Or, if there is not a white neutral wire like a single-pole switch, I can put the other metal tip on my finger and the light just barely lights up.
Well, when about to replace a 30 old S.P. by my kitchen sink I went to check to see if there was power running to the switch. I grabbed my neon-test, put one metal tipped needle on the black wire screw and tapped my finger on the other and the light lit up slightly for a brief second before POP! and a puff of smoke.
After I made sure I still had my eye-brows I looked and part of the screw is melted, the side of the switch is burnt black and my beloved neon-testers metal tip is melted.
What happen?
Well, I theorized the screw was loose on the side of the switch and think an arc was created and it was a one time deal.
Well, I was wrong, because in the next two days, all when working on the same wall in the kitchen (two circuits), I've had three more loud pops and a quick burst of light when trying to test.
I thought maybe my neon-tester had gone bad, but it even happen with a new tester.
Any comments/suggestions? I do plan on calling a certified electrician to come check everything out b/c in my three years of doing electrical work around the house I've never had this happen. I do though want to learn what is happening.
Thanks!