Hi, All,
I’ve got a bit of a mystery.
As I was painting a wall last night I ran my pinkey across the top of a 3-way wall switch (the flange that screws into the box) and – ZAP! (no paint on or near the switch yet).
Whoa, I thought, how’d I screw *that* up? I figured the ground wires must’ve come in contact with the hot when it got pushed back into the box. The ground is connected to the frame of this switch. So, I got a bright light on the situation, and reassuringly the ground wires were smushed away in the back of the box, far away from any of the terminal screws.
So, that wasn’t it. I must have a short somewhere else in the circuit, I thought, but why wasn’t the breaker tripping? So, I went to the other switch, to the light fixtures, etc., and couldn’t find any problems, and just to be sure I used my built-in current finder and none of the grounds were hot.
So, I replaced the switch with a new one, and it’s just fine. To add insult to injury I was replacing an $8 “SPEC Grade” switch from the electrical supply house with a $3 one from the bigbox store.
This leads me to believe the switch itself must’ve been faulty, but that seems so unlikely. I can’t think of any way for the switch to fail that would allow current to cross over from the hot to the ground (the switch was still functional).
I’ve got to get some new batteries for my multimeter to test the switch, but assuming that’s not the problem, what else could have caused this situation?
Thanks,
-Bill
Replies
What kind of "zap"
First of all this time of year static electicity is always a possilbility.
And more then once I have felt a "tingle" and search and checked and found out that I had a sliver of metal in my finger or there was a sliver of metal on the device.
Take you multi meter and on voltage measure between the "screw" to to the ground connection on another circuit.
Repeat the samething for the ground wire in the box to a another ground.
Should measure zero (or a few 1/10's at the most).
If that show zero then repeat measuring the resistance.
If it does not show near zero resistance then the ground is open somewhere.
Yes, I too can get a wicked static zap from me to the switch frame (because it is conductive and grounded). Worst on a cold day with dry indoor air. And when I've got my moosehide mukluks on the nylon carpet. Based on the size of the spark, it is about 2,500 or 3,000 volts. But really low amps!David Thomas Overlooking Cook Inlet in Kenai, Alaska
Sounds like it was probably static. I've never felt suck an energetic static shock, this felt like 120V AC, but maybe the solid ground helps exaggerate the fun?
Not what I was expecting, but the theory fits the data. :) Thanks, guys.
So far so good. Always good to cover the simple stuff first.
In some conditions an arc can form inside a switch and carbonize parts of the plastic. This could cause the steel frame to become energized under extreme conditions.