Electrical mystery

[colonelkirby]

I had a switch go bad over the weekend. Picked up a new one and went to the panel to turn off the breaker to swap it in. Old panel, circa 1972 is my guess, and not at all clearly labeled. Couldn't find the right breaker to get the power cut to the bad switch. Been in the house a long time and its the first time I had ran into this. Long story short, I had to turn off 2 20amp, non contiguous btw, breakers to get the power cut to the bad switch. This perplexes me a bit. So trying to investigate WTH this is about, I tested every outlet and device that was now powered down with both breakers off. Then I turned back on just one of the breakers and everything that had been powered down is now powered up. What am I up against here? I left the panel in the state with 1 off and 1 on. Should I be worried? Years ago we had some work done that was suspect at best in the kitchen and that is the general area of the circuits in question. Worried that we might potentially have a dangerous situation that needs addressing.

TIA

 

[Jimrahbe]

Col,

What kind of switch? Just a typical single pole light switch?? What is the switch for?

Edit.. As a test, turn off the breaker that it now on, and turn on the breaker that is now off, and see if you have power to the switch.

Sounds to me like you might have two sources of power for the same switch.

Thanks,

Jim R.

 

[colonelkirby]

Col,

What kind of switch? Just a typical single pole light switch?? What is the switch for?

Edit.. As a test, turn off the breaker that it now on, and turn on the breaker that is now off, and see if you have power to the switch.

Sounds to me like you might have two sources of power for the same switch.

Thanks,

Jim R.

Its a dual single pole switch Decora Single-Pole / Single-Pole Combination Switch. Top is for disposal and bottom is power to dishwasher. It occurred to me as I was writing my post to try the reverse of the current state. I will try that directly.

 

[ajw22]

Its a dual single pole switch Decora Single-Pole / Single-Pole Combination Switch. Top is for disposal and bottom is power to dishwasher. It occurred to me as I was writing my post to try the reverse of the current state. I will try that directly.

That is two switches in one housing. Each switch can be fed by its own circuit and circuit breaker.

 

[Bama Rambler]

Long story short, I had to turn off 2 20amp, non contiguous btw, breakers to get the power cut to the bad switch.

That is two switches in one housing. Each switch can be fed by its own circuit and circuit breaker.

Assuming that the circuits are on the same phase, whoever did the wiring for these circuits, did the right thing. If they had fed the circuits with adjacent breakers then you would wind up with 240 volts between the line terminals of the switch. The way it's wired there will be zero potential between the terminals, but 120 volts between each terminal and neutral/ground.

It also sounds like you may not have broken off the 'bridge' tab between the terminals on the new switch when installing it. If that's the case, then either breaker will feed both loads.

 

[colonelkirby]

Turned off the breaker that was on and turned on that wich was off. Every plug/device remained energized. I have not pulled the bad 'dual' switch yet but it sure sounds like I will find what @Bama Rambler suggests re. the tab not being removed. If that's the case, surely it's proper to remove that tab?

 

[Newdude]

If that's the case, surely it's proper to remove that tab?

If the device is daisy chained, for example a room outlet that the power enters anf leaves to the next outlet, those tabs bridge the screws.

If the device has 2 feeds, for example, the top half of an outlet is on a switch, and the bottom has full time power, that tab needs to go to seperate the two. A bath fan and vanity light would be another scenario that you could power 2 devices from that switch. But dishwasher and disposal likely got their own circuit each. The 2 hots should have been your heads up.

 

[Mdragger88]

Why does your dishwasher need a switch?
Generally there’s a switch for the disposal
& the disposal & dishwasher may be using the same outlet but one side of the outlet would be switched (disposal) & the other side constant power (dishwasher).
If both yours are hard wired then you could just use the switch box as a junction box for the dishwasher & only have a single pole switch for the disposal.
If both circuits are on the same switch w/ the tab broken then the associated breakers should have handle ties as they share a device yoke.

 

[proavia]

Look at the old switch to see if the tabs are there or not. Chances are goo they are not.
In many jurisdictions, the dishwasher must be on its own separate circuit breaker. No lights, other plugs or garbage disposal.....

 

[Bama Rambler]

Turned off the breaker that was on and turned on that which was off. Every plug/device remained energized. I have not pulled the bad 'dual' switch yet but it sure sounds like I will find what @Bama Rambler suggests re. the tab not being removed. If that's the case, surely it's proper to remove that tab?

Given that there should be two completely separate circuits (Dishwasher and Disposal) not only is it proper, but it's required that the tab be removed.

P.S. I also think that you will find the tab not broken off on the old switch.

 

[Methuselah]

It is unusual to have a dishwasher run off a switch. I suspect the easiest way to find out what's going on is to cut both breakers off and unhook wiring on the switches. Then, you can turn on one breaker at a time and test voltage with a DMM or neon bulb tester.

Label wires first, maybe take notes and definitely a pic or two so you know how to put stuff back.

Perhaps post the pics if tests don't clarify.

BTW, switches almost never go bad, consider something may be going on...