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Discussion Starter · #1 ·
I recently removed the non-vented over the range vent hood to install an OTR microwave. I have mapped out every outlet and switch in the house, and the vent hood and now microwave are plugged into an outlet that was high over the range. Its a non dedicated circuit that starts over the countertop with a GFCI, has another outlet over the countertop, and then this outlet that the microwave is currently plugged into. The GFCI and last outlet on this circuit in locations that I really don't think I will ever use, and don't think I have yet. I have had the microwave about 6 months and have used it twice to heat water for oatmeal, (all new kitchen appliances, and I use my old toaster oven).

All the breakers are 20 amp, all the outlets are 15 amp, and all the wire is thicker than 16 gauge, (not sure if 14 or 12).

1. The microwave specs say 1000 watts / 13 amps at 120 volts. My math tells me 1000 / 120volts = 8 1/3 amps?

2. Its currently just me in the house for now. I can certainly get away with not using the other two outlets during the rare time I use the microwave. Are there any other concern that might come up until this is on a dedicated circuit?

3. I am about 99% certain this will need to eventually be on a dedicated circuit to be compliant. There is no dedicated microwave circuit in the kitchen. I have read someone say they were quoted $1,000 for this circuit. If I HAD to sell my house tomorrow. I would take a picture of it, measure it for exact dimensions, I would remove the other two outlets off this circuit and cap them off, then drywall and paint it before I ever paid $1000 for it.

I have other wiring (including the kitchen lighting) just ran overhead in the attic, and that would be my plan. My breaker panel has a breaker that is already there as SPARE. I have started with the outlets and switches, but running new cable and connecting to the panel is a step or two up from what I have done so far.

This seems like I would just remove the wiring from this outlet, run the new wiring to the breaker, and connect it. Is it as easy as figuring out how to do all that? Thank you.
 

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Not sure on your area but where I am I needed a dedicated AFCI line for the OTR microwave when I did a total kitchen remodel and re-wire. Also needed another one for dishwasher I added.



Retired guy from Southern Manitoba, Canada.
 

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1. The microwave specs say 1000 watts / 13 amps at 120 volts. My math tells me 1000 / 120volts = 8 1/3 amps?
That's not exactly how the microwave power works. There are transformers and other electronics that use power inside of the microwave to make it work, which equal losses of power.

The microwave should 100% be on a dedicated circuit. It probably even states that in the manual if you still have it.

In the meantime, if you are using the microwave and the circuit starts tripping, unplug or shut off some stuff on the circuit.

Sent from my new phone. Autocorrect may have changed stuff.
 

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...running new cable and connecting to the panel is a step or two up from what I have done so far.
Thats about where I was when I installed my my OTR microwave. I had a dedicated circuit, but it ran to a terrible place for a microwave. I called an electrician. Besides the fact that I don't like going into the panel, it was a long run, and figured a guy that fishes wires every day, would do a lot less drywall damage than I would.

Don't recall what I paid, but it wasn't no thousand dollar.
 

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Discussion Starter · #5 · (Edited)
Not sure on your area but where I am I needed a dedicated AFCI line for the OTR microwave when I did a total kitchen remodel and re-wire. Also needed another one for dishwasher I added.



Retired guy from Southern Manitoba, Canada.
The dishwasher, refrigerator, disposal, and stove all have their own dedicated circuits. I have mapped it all out checking every outlet and switch, they just didn't do one 20 years ago when they did this house.

That's not exactly how the microwave power works. There are transformers and other electronics that use power inside of the microwave to make it work, which equal losses of power.

The microwave should 100% be on a dedicated circuit. It probably even states that in the manual if you still have it.

In the meantime, if you are using the microwave and the circuit starts tripping, unplug or shut off some stuff on the circuit.

Sent from my new phone. Autocorrect may have changed stuff.
That makes sense, and yes it does say that in the install instructions.


EDIT: So if they say 13 amps; (then) x 120volts = 1560 watts (then / 1000) = 64% efficient? Would this also be the right way to say it; "Its the difference in the appliance's accountable/assigned input, compared to its efficient output, when you factor in the appliances non-perfectly efficient components, that have mechanical loss such as friction and heat loss" ?

Thats about where I was when I installed my my OTR microwave. I had a dedicated circuit, but it ran to a terrible place for a microwave. I called an electrician. Besides the fact that I don't like going into the panel, it was a long run, and figured a guy that fishes wires every day, would do a lot less drywall damage than I would.

Don't recall what I paid, but it wasn't no thousand dollar.
I would have to figure out what is the best and proper way for me to do it, but I have plenty of time to work on it right now. I just need to figure out just how. I'm learning most everything is cheaper to just buy the tools and do it myself.




I could even throw tape over the outlets in case company comes by. I know its not ideal, but its no different than a dedicated circuit if nothing gets plugged in to the other outlets right?
 

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EDIT: So if they say 13 amps; (then) x 120volts = 1560 watts (then / 1000) = 64% efficient? Would this also be the right way to say it; "Its the difference in the appliance's accountable input, compared to its efficient output" ?
I am by no means a microwave expert.

I'm not 100% sure if the 1000 watts is what is fed to the equipment that actually heats the food or how they work.

The 13 amps may also be the max power it will use.

It's an OTR microwave, so it will have a light, and a fan in addition to normal microwave parts.

For example, My microwave states: "max output power 900 watts" and the magnetron operates at 4.15KV, so the transformer has to supply 900 watts output while providing the voltage as well. Now you've got me curious about the power use... I might measure that later.

Sent from my new phone. Autocorrect may have changed stuff.
 

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EDIT: So if they say 13 amps; (then) x 120volts = 1560 watts (then / 1000) = 64% efficient? Would this also be the right way to say it; "Its the difference in the appliance's accountable/assigned input, compared to its efficient output, when you factor in the appliances non-perfectly efficient components, that have mechanical loss such as friction and heat loss" ?

You got it. The magnetrons used in microwave ovens are about 65% efficient in converting the electrical energy input into microwave energy. A little bit of additional energy is used to power the fan and light, lowering the overall efficiency further.
 
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