If the switches or outlets are still mounted in the box while you are
testing them, the screw terminals are very close to the metal edge of the
box, which is grounded. If your neon tester probe bridged the gap between
the outlet and the box, you would have exactly as you describe


"Native" wrote in message
ps.com...
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!