Customer getting shocked by disposal switch

[John Wayne]

So I went on a service call about a month ago and the customer said they were getting shocked when they turned on the disposal. I couldn’t find anything wrong so I replaced the switch and said to call if it happens again. Well she called and said it’s happening again. Any thoughts?

 

[Little Bill]

That switch and plate should be all plastic. Only metal (that you could touch with plate on) would be the plate screws. Sounds like a static shock if anything. If you go back, I would suggest taking an extension cord and plugging it in to a receptacle that is not on the same circuit as the disposal. Take your meter and measure from the ground hole in the ext cord to the metal screws on the disposal switch. If you have much of any voltage there then you might investigate farther. I highly doubt the HO is getting a "true" shock just touching the switch.
This is assuming a normal switch w/plastic handle, and plastic cover plate.

 

[drcampbell]

How old is the house? What modifications have been made?
If it's older than c.1960 or so, check the plumbing. If there's a fault in the disposal and the house has plastic water pipe, the kitchen sink could be energized, which might result in a shock when touching it and a properly-wired, properly-grounded switch.

 

[John Wayne]

Thanks Bill - I will try that tomorrow

 

[John Wayne]

House was built in the 50s and I don’t remember if it had been remodeled

 

[Gene B]

Flipping a switch isn't a two handed job. What's the other hand touching?

 

[oldsparky52]

Flipping a switch isn't a two handed job. What's the other hand touching?

+1

Ask the customer to pay attention to what else they are touching when it happens.

Did you measure from the switch to the sink to check for a voltage potential?

 

[S'mise]

I'm sure you checked the wiring integrity first.

It may be an older disposal with internal insulation breakdown.
Some disposals have a supplemental ground screw that can be bonded under sink but replacement is advisable if it's the problem.

 

[John Wayne]

Good point - I assume she’s touching the faucet or sink with the other hand. I will find out today how she’s doing it

 

[romex jockey]

bond the plumbing....~RJ~

 

[S'mise]

Most operate the disposal by turning on the water with one hand and toggling the switch at the same time with the other. Sometimes one hand is touching the basin, but either way they're essentially grounding themselves.

 

[mpoulton]

This is one of the few things non-contact voltage testers are really good at: finding random things which are unexpectedly electrified. The switch may not be the hot part.

 

[GoldDigger]

This is one of the few things non-contact voltage testers are really good at: finding random things which are unexpectedly electrified. The switch may not be the hot part.

On the other hand, if you are holding the non contact tester and are coupled to an energized surface, the tester will alert for ground.