I've seen similar questions asked, but none that address my particular situation directly, so please bear with me.

I recently purchased a condo that has a garbage disposal and an instant hot water dispenser under the sink. They both run off the same outlet, with a switch for the disposal side. I don't use the disposal, so I've unplugged it. I would like to use the switched outlet to power the hot water dispenser so that I can shut it off at night when it's not being used; however, the dispenser's manual says, "The wall outlet powering your dispenser must have power supplied to it continuously. This outlet must be fused and should not be controlled by the same wall switch that operates the dispenser, unless you have a SinkTopSwitch™ from InSinkErator®."

In my mind, a switch is a switch, and as long as I'm not using both appliances at once, I don't see what difference it would make, unless InSinkErator's switch has a higher rating. Nevertheless, I don't want to burn the house down in my quest to save a few dollars' worth of electricity.

Here's the current setup:

enter image description here

Many thanks.

  • Why do you want to shut off the hot water dispenser when it's not being used? Unless it's faulty (in which case it shouldn't be used anyway) it's not drawing any current when it's not being used, so switching it off serves no purpose.
    – brhans
    Jun 12, 2023 at 14:57
  • @brhans that's only true if it's a tankless. A tankless "water for tea" heater would be awfully slow. My rule of thumb is 40A @ 240V per GPM for shower temp, and probably twice that for tea. So tankless would be, golly, a cup a minute? I think it contains a small tank good for a few cuppa's. Jun 13, 2023 at 3:07
  • @Harper-ReinstateMonica - there's a tank in that little unit? I've never seen one that small, but I guess it's possible.
    – brhans
    Jun 13, 2023 at 3:22
  • @brhans a plug-in heater will be 1500W or 5120 BTU/hr... or about 1.5 BTU/sec. Figure an 8 ounce cup of tea weighs a half pound. Jun 13, 2023 at 3:23

3 Answers 3


Yes, you can plug the dispenser into a switched outlet. The dispenser should not be controlled by the same wall switch that operates the disposal. Because then, you would have to run the disposal whenever you wanted hot water.

Do some research, or experiment, to see how much energy is used by dispenser when it is not in use. You will probably save very little to nothing by turning it off at night, and in return you'll have to wait a minute or so for your first cup of hot water in the morning.

Also, even if you don't regularly use the disposal, you'll have to run it from time to time to get rid of any food or crud that falls into it. If you truly intend to never operate it, you should remove it.


The mentioned "SinkTopSwitch™ from InSinkErator®" is a switch with two outlets one of which is always powered at any time. The only reason they allow you to use it with this dispenser is if a disposal is plugged in to the other end, you won't leave the disposal running for a long time, and when you turn the disposal off, it will restore power to your instant hot water dispenser.

If the dispenser is based on a small tank (as otherwise it would produce water really slowly), putting it on a switch would largely defeat the idea of instant hot water, as the switch would need to be on for several minutes to actually get the water hot. I suppose if you turn it on a while before meal/coffee/tea/whatever-uses-hot-water time, use it during that period, and turn it off after such a time is well passed, it might be okay, but that is certainly not the design intent.


The exact quote from the manufacturer is as follows:

A standard, earthed (grounded), ground fault circuit interrupter (GFCI) electrical outlet is required under the sink for the instant hot water dispenser’s electrical power. The wall outlet powering your hot water tank must have power supplied to it continuously.

This GFCI outlet must be fused and should not be controlled by the same wall switch that operates the disposer unless you have a SinkTop Switch™ from InSinkErator®. Fuse/circuit breaker required is 15 amp for 120 volt and 10 amp for 230 or 220-240 volt.

For reference, the water heater is rated 6.25 amps with a 2/3 gallon tank. If you have a 1/2 hp disposal drawing 10 amps, then you're at or above the circuit limit. The reason they make an exception for the air switch is this:

Power module outlets are controlled by an internal alternate–action switch. This means either one or the other outlet will be energized at all times.

In other words, they want you to buy their brand of switch, and the water heater will work just fine on switched power.

Since you don't have a GFCI in the photo, I can't recommend using that water heater at all. A GFCI or dual function circuit breaker would be a good investment here.

  • GFCIs can live in the panel. Just because there isn’t one in the photo doesn’t mean there isn’t one in the circuit.
    – nobody
    Jun 16, 2023 at 21:17

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