Outlet for garbage disposal has power but switch won't turn it off

[DIYJoe59]

What are you using to test the wiring? If it's a contactless device, those can be misleading. Well, even a multimeter can be misleading to the casual user!

Here's a pic of the device I used to test the current. I should have tested earlier but just now found that there is no current in the wires at the switch. (Tested other live outlets in the house and they registered fine.)

 

[Jadnashua]

This is where a little understanding is important...when the switch is closed, and you measure from one switch contact to the other, you're essentially just measuring the same wire. That device would not show any voltage or current unless you placed one lead on a ground. If you did that, one lead would show hot when the switch was opened, and the other would not. When you close the switch, you should get the same thing from one side of the switch to ground as the other since all the switch is doing is connecting the two sides together - you're measuring essentially the same point.

 

[Sponsor]

 

[DIYJoe59]

You have done everything except change the outlet, so change the outlet. It is possible there is a short inside the outlet if you ever took one apart. A power surge or lightning strike nearby could have done it in though rare.

With two NM cables and the way it is wired, power for the disposal is coming from the switch. The other is always hot for the dishwasher. Pics of the switch would be nice.

Ok, I've attached photos of the wiring at the switch. Also, just tested the current (should have done earlier) and found no current running through those two wires. So, switch was apparently not getting any power. What can I do next?

 

[DIYJoe59]

This is where a little understanding is important...when the switch is closed, and you measure from one switch contact to the other, you're essentially just measuring the same wire. That device would not show any voltage or current unless you placed one lead on a ground. If you did that, one lead would show hot when the switch was opened, and the other would not. When you close the switch, you should get the same thing from one side of the switch to ground as the other since all the switch is doing is connecting the two sides together - you're measuring essentially the same point.

Ok, great, thank you. So, I now tested it the correct way, with one lead to the ground and the other to each wire. You are correct--one wire showed hot when I tested it this way. But somehow the switch still doesn't turn off the disposal when it is plugged in under the sink. And this has happened with several new switches that I tried installing.

 

[Reach4]

With the breaker on,

1. what voltage do you see with one test lead on E and the other on F? (120 volts would be normal)
2. what voltage do you see with one test lead on E and the other on G? (about zero volts would be normal, depending on the characteristics of your tester)

If the switch is already back in place, provide the answers for both positions of the switch. If you show 12o volts for each measurement, replace the outlet. Remember to remove the tab between the two hots on the new switch.

 

[hj]

Unfortunately, since we cannot SEE how you are testing things, and your descriptions are sometimes illogical, we would have to be there to do our own testing to sort this out.

 

[WorthFlorida]

The F wire is definitely the switched lead for the disposal.

 

[Jadnashua]

Okay, with the switch out of the circuit, and the disposer still powered, there's obviously something else connecting power to that terminal on the receptacle. Without some additional info, we can't say from here. If the insulation on the wiring is compromised, you could be getting power between two wires that isn't obvious. Or, you've got something wired up wrong.

 

[DIYJoe59]

Thanks to all for the sound advice. We'll have to have someone come over and check it all out.