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

[DIYJoe59]

My installed disposal stopped working. I unplugged it and plugged it back into the outlet (top one) that is wired for it, and it worked but then the switch (which is above the counter) didn't turn it off. I'd reset the unit and the circuit breakers. Tried again to unplug and plug it in--same thing.

So, I installed a new switch and also decided to go ahead and install a brand new disposal anyway since the other unit was pretty old. Still, when I plug the disposal into the designated outlet, it runs, but the switch still doesn't work, so I can't turn it off with the switch once it's plugged in.

We have split wiring to the receptacle under the sink--the top outlet is connected to the switch that turns the disposal on/off, and the bottom outlet is always hot, where the dishwasher plugs in. I understand that this is a common setup.

I've viewed numerous videos and read countless forums looking for answers to this issue. However, no one can provide an adequate explanation for *why* this might have happened and what, exactly, might be going on with the wiring. Most of the advice simply says to call an electrician or HVAC specialist because you probably need to have something "rewired". But I have *no* clues as to what that might be causing this and why, out of the blue, this issue would occur. Also, is there anything else we can check before calling an electrician.

I have installed these disposals before on many occasions. But this issue is new to me--where the outlet gets power and the disposal works, but the switch doesn't. Any advice is greatly appreciated!

 

[Reach4]

Is the dishwasher outlet always live?

 

[Sponsor]

 

[DIYJoe59]

Is the dishwasher outlet always live?

Yes, it is

 

[Reach4]

Did you remember to break off the jumper tab between the two hot screws on the outlet?

 

[hj]

Are you sure you have the disposer plugged into the correct half of the duplex receptacle. There is NO RULE that the top outlet is for the disposer. The disposer and the switch were probably to two things that were NOT the problem, so you wasted your money on them.

 

[DIYJoe59]

Did you remember to break off the jumper tab between the two hot screws on the outlet?

Not exactly sure what that means, but this outlet was working fine for many years with the old disposer--I did not do anything to the outlet itself, as it is working fine.

 

[DIYJoe59]

Are you sure you have the disposer plugged into the correct half of the duplex receptacle. There is NO RULE that the top outlet is for the disposer. The disposer and the switch were probably to two things that were NOT the problem, so you wasted your money on them.

Yes, I am sure that the disposer is connected to the correct outlet. Our house was wired such that the top outlet was for the disposer and switch, bottom one (always hot) for the dishwasher. We had a disposer installed for many years with this configuration and it has worked fine until now.

 

[Reach4]

Then probably you mis-wired somehow, or the new switch is defective.

 

[hj]

You are "SURE" it is plugged into the correct opening, BUT, have you actually TRIED plugging it into the other one to be sure? If the outlet is wired correctly, the only way what you describe could happen is with a defective, or miswired, switch. If the switch is good, then the problem is in the outlet. There is NO WAY the problem could be in the disposer.

 

[DIYJoe59]

Then probably you mis-wired somehow, or the new switch is defective.

Ok, thanks. I tried wiring two different new switches on top of the counter (on/off switch only to Garbage disposal), changing the wiring on the different terminals to find out if it cuts off the current and it did not work. The only thing left is the receptacle/outlet on the bottom under the sink.

I did take it out, looked at the wiring to see if any wires were loose, and I didn't see anything loose. And this is the same wiring that's been working for 15 years.

Under the sink the receptacle with the top outlet goes to disposer (and to the switch) and the bottom outlet (always on) goes to dishwasher. Both outlets have power. It's just that I can't operate the disposer now with the switch --the connection is always on and I can't turn it off.

 

[DIYJoe59]

You are "SURE" it is plugged into the correct opening, BUT, have you actually TRIED plugging it into the other one to be sure? If the outlet is wired correctly, the only way what you describe could happen is with a defective, or miswired, switch. If the switch is good, then the problem is in the outlet. There is NO WAY the problem could be in the disposer.

Yes, positive that the disposer is plugged into correct outlet. Our house was wired such that the top outlet was for the disposer and switch, bottom one (always hot) for the dishwasher. We had a disposer installed for many years with this configuration and it has worked fine until now. We now know, based upon troubleshooting, that it was not the disposer that was the problem. I've tried several new switches and still the same problem--disposer works when plugged into the outlet but I can't turn if off with the switch up above.

So based upon what you have said, the problem is likely with the outlet. Does this mean that installing a new outlet might solve the problem? (And why would that outlet just go bad after 15+ years of working fine?)

 

[Reach4]

Electrical hot is getting to the disposal outlet somehow. It is either coming via...

1. the switched hot wire from the switch.
2. a short to the dishwasher hot in the outlet box.

Does this mean that installing a new outlet might solve the problem?

It might. If the problem is in the outlet box, it also might be that reinstalling the old outlet could solve the problem.

(And why would that outlet just go bad after 15+ years of working fine?)

It could be that a strand of wire that was almost bridging between the two hot screws moved a tad. It could be that the hot tab jumper was not totally removed, and it started bridging across.

If you could access the isolated conductors, you could use a clamp-around ammeter to see which conductor was carrying the current.

 

[DIYJoe59]

Electrical hot is getting to the disposal outlet somehow. It is either coming via...

1. the switched hot wire from the switch.
2. a short to the dishwasher hot in the outlet box.

It might. If the problem is in the outlet box, it also might be that reinstalling the old outlet could solve the problem.
It could be that a strand of wire that was almost bridging between the two hot screws moved a tad. It could be that the hot tab jumper was not totally removed, and it started bridging across.

If you could access the isolated conductors, you could use a clamp-around ammeter to see which conductor was carrying the current.

 

[DIYJoe59]

Ok, thanks, will look into these suggestions~

 

[DIYJoe59]

Electrical hot is getting to the disposal outlet somehow. It is either coming via...

1. the switched hot wire from the switch.
2. a short to the dishwasher hot in the outlet box.

It might. If the problem is in the outlet box, it also might be that reinstalling the old outlet could solve the problem.
It could be that a strand of wire that was almost bridging between the two hot screws moved a tad. It could be that the hot tab jumper was not totally removed, and it started bridging across.

If you could access the isolated conductors, you could use a clamp-around ammeter to see which conductor was carrying the current.

Ok, thanks, will look into these suggestions~

 

[WorthFlorida]

Are you sure you have a two way switch, not a three way? Here is a typical set up. As stated above it could be the top or bottom outlet that is switched and the other is live all the time. Color may vary where the black is switch and the red is live. Most setups there are two circuits feed by one cable. It can be feed by one circuit such in an old house with only one outlet and a dishwasher or disposal was added. With one circuit the black would go to the switch and then branched off the the live side of the outlet and a red wire would run to the other side of the outlet.
If you do not remove the break-a-way tab, both outlets will always be live.

 

[DIYJoe59]

Ok, thanks for the wiring info. Some of you on this thread suggested checking the wiring at the outlet under the sink so I took the outlet out and have attached photos. I do not see anything out of place or that looks damaged. Recall that this is the outlet under the sink where our disposal and dishwasher are plugged in. Our disposal was wired with a switch (that is above the sink) to the top outlet. The problem is that when we plug in the disposal now, it runs but I cannot turn it off with the switch. I've put in several new switches, double checking the wiring when I put in the switches, and still have the same problem. Also, it's a new disposal. The switch is definitely a two-way. This wiring, the way you see it below, has been like that for over 15 years and we've had no problems until now with the disposal or with using the switch for it.

If you see anything that looks out of place here, please advise. After looking at this, do you still suggest that I put a new outlet? Thanks much~

 

[DIYJoe59]

Are you sure you have a two way switch, not a three way? Here is a typical set up. As stated above it could be the top or bottom outlet that is switched and the other is live all the time. Color may vary where the black is switch and the red is live. Most setups there are two circuits feed by one cable. It can be feed by one circuit such in an old house with only one outlet and a dishwasher or disposal was added. With one circuit the black would go to the switch and then branched off the the live side of the outlet and a red wire would run to the other side of the outlet.
If you do not remove the break-a-way tab, both outlets will always be live.


View attachment 54638

Ok, thanks for the wiring info. Some of you on this thread suggested checking the wiring at the outlet under the sink so I took the outlet out and have attached photos (in a new post). I do not see anything out of place or that looks damaged. Recall that this is the outlet under the sink where our disposal and dishwasher are plugged in. Our disposal was wired with a switch (that is above the sink) to the top outlet. The problem is that when we plug in the disposal now, it runs but I cannot turn it off with the switch. I've put in several new switches, double checking the wiring when I put in the switches, and still have the same problem. Also, it's a new disposal. The switch is definitely a two-way. This wiring, the way you see it below, has been like that for over 15 years and we've had no problems until now with the disposal or with using the switch for it.

If you see anything that looks out of place here, please advise. After looking at this, do you still suggest that I put a new outlet? Thanks much~

 

[Jadnashua]

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!

 

[WorthFlorida]

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.