"Jeff Wisnia" wrote in message
...
rich wrote:
I have an old house (1858) that was wired in the 30's with romex. I was
changing a light fixture. I turned the power off to the circuit removed
the old fixture and while I was wiring in the new fixture I received a
slight shock when I touch the metal box and one of the wires.
Any ideas?


If the "slight shock" was just a tingle, chances are there's just a
little capacitively coupled current from an energized conductor running
in close proximity parallel to what would otherwise be considered an
"open" lead.

Or, there could be a high resistance path created by dampness or through
years of crud film accumulating between an energized circuit and
something connected to the wiring you touched.


Or back feeding through a "leaking" neutral and then to ground. In other
words, there might actually have some current running through it. In sound
equipment it causes a buzz when equipment is plugged into different phases
of the breaker box and there is a current between neutrals.

If the fixture job is already finished, then that's that. But it's
always wise to use a test light or voltmeter to make sure things which
are supposed to be "off" really are.

HTH,

Jeff

--
Jeffry Wisnia

(W1BSV + Brass Rat '57 EE)

"Truth exists; only falsehood has to be invented."