Residential single pole switch frame energized no grounding conductor

[Matt Mckenzie]

Working on existing residential wiring I noticed a single pole switch where the previous electrician cut the grounding conductor off of a single pole timer. I installed a new timer & I connected the ground & the breaker tripped. I disconnected the ground & with the timer dangling out of the switch box the frame of the timer is energized. I tried a brand new standard single pole switch & with no ground the switch frame is energized when the switch is isolated hanging from the wall. How is this even possible?

 

[MAC702]

The breaker tripping on the first one is definitely a sign something is up. But also, how are you testing that the frames are energized on the others?

Pictures, timer models, etc, all help with brainstorming.

 

[Matt Mckenzie]

The breaker tripping on the first one is definitely a sign something is up. But also, how are you testing that the frames are energized on the others?

Pictures, timer models, etc, all help with brainstorming.

the other frames are not energized only this one & it doesn't matter if it's a timer or a standard switch

 

[GoldDigger]

When you say "switch frame", are you referring to the yoke that attaches the switch to the box?
There should be no solid voltage there, but capacitive coupling inside the switch might well cause a phantom voltage to show up when you use a high impedance meter. But that would not trip a breaker.

Unless the load is shorted or the switch is defective I cannot figure a reason for your particular combination of symptoms. +

 

[Matt Mckenzie]

When you say "switch frame", are you referring to the yoke that attaches the switch to the box?
There should be no solid voltage there, but capacitive coupling inside the switch might well cause a phantom voltage to show up when you use a high impedance meter. But that would not trip a breaker.

Unless the load is shorted or the switch is defective I cannot figure a reason for your particular combination of symptoms. +

Yes switch frame the metal part that mounts to the box...... hmmm

 

[Little Bill]

Yes switch frame the metal part that mounts to the box...... hmmm

If you don't have a meter with "low Z" setting or a "wiggy" you can take a pigtail socket with a light bulb installed. Take the leads from the pigtail socket, one to the frame/yoke and one to a known good ground or neutral. If the bulb lights then you have voltage on the yoke but if not, then you are reading a phantom voltage.

You did however have a problem with the first timer that tripped the breaker but I think the voltage you are reading now is phantom voltage. I can't see how you would have voltage on the yoke of a completely different switch that you used in place of the timer switch. Unless the hot/ungrounded conductor was connected to the ground screw.