Over-the-range microwave: Is 15 amps enough?

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Old 01-11-16, 10:56 PM
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Over-the-range microwave: Is 15 amps enough?

I currently have a range hood/light over my stove that I'd like to replace with a microwave. When I checked to see which breaker it was on, I saw that it is a 15 amp circuit.
All of the models I looked at are rated at 15 amps, but you shouldn't max that out, right? There should be some wiggle room? My dining room light is also on this circuit (that's the only other thing.)
 
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Old 01-11-16, 11:06 PM
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A fixed in place cooking appliance falls under the 50% rule. If the amperage of the appliance exceeds 50% of the circuit capacity there can be nothing else on the circuit. A fixed in place microwave/hood often exceeds 7.5 amps so a dedicated circuit is almost always used. What is the amp rating of the microwave?
 
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Old 01-11-16, 11:11 PM
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The instructions will call for a dedicated circuit of 15 amps or more.
 
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Old 01-12-16, 05:37 AM
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What is the amp rating of the microwave?
I haven't purchased one yet. I've been looking online, and most of them say this under "specifications":

Electrical Specification

Amperage
15 amperes
Voltage
120 volts
 
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Old 01-12-16, 06:00 AM
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My dining room light is also on this circuit (that's the only other thing.)
I wouldn't waste time looking for a Microwave Hood combo that uses less power, they are all about the same.
It's common for the old vent hoods to be on a lighting circuit and this is insufficient for the oven.
It's even more uncommon for a single light to be the only device on a circuit.
If you're sure the dining lights are the only thing on this circuit, you can run power to the lights from another circuit and use this 15amp circuit for the oven.
 
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Old 01-12-16, 08:44 AM
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A fixed in place cooking appliance falls under the 50% rule. If the amperage of the appliance exceeds 50% of the circuit capacity there can be nothing else on the circuit. A fixed in place microwave/hood often exceeds 7.5 amps so a dedicated circuit is almost always used. What is the amp rating of the microwave?
What happens when the draw of a fixed microwave exceeds 10 A? Many of the new high power microwave have 1200 W of microwave power so when you add in the overhead electronics there draw at full power is over 10 A.
 
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Old 01-12-16, 09:28 AM
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What happens when the draw of a fixed microwave exceeds 10 A
Nothing happens except the oven needs to be on a dedicated circuit. It's OK to exceed 50%, but not while sharing with other receptacles or lights.

Anyone considering changing out a vent hood for a microwave combo should expect to run a new dedicated 20amp circuit. There are houses pre-wired for a microwave, but rare.
 
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Old 01-12-16, 10:18 AM
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Electrical Specification Amperage
15 amperes
That probably just describes the circuit they will work on not the actual amps they draw.
 
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Old 01-12-16, 10:33 AM
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Anyone considering changing out a vent hood for a microwave combo should expect to run a new dedicated 20amp circuit.
That's what I was thinking, and the reason I posted the question. Unfortunately, running a new circuit is also beyond my skill set, so I guess it's time to get an estimate from an electrician.

There are houses pre-wired for a microwave, but rare.
My house was built in 1977- right about the time microwave ovens were coming out. I probably never crossed their minds that somebody would want to take one of those newfangled things and put it over the stove.
 
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Old 01-12-16, 10:39 AM
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Running a new circuit isn't that hard. We can walk you through it.
 
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Old 01-12-16, 11:51 AM
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Running a new circuit isn't that hard. We can walk you through it.
Well, maybe I can. Running the cable through the attic and fishing it down the wall is no problem. I'm just nervous about making a connection inside the panel, as I've never done that before.
 
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Old 01-12-16, 12:23 PM
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I'm just nervous about making a connection inside the panel, as I've never done that before.
Just turn off the main breaker and stay away from the main breaker when working. You can usually even insert the new wire into the breaker and tighten the terminal screw before you install the breaker.
 
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Old 01-12-16, 01:54 PM
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Will this require a permit?
 
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Old 01-12-16, 03:21 PM
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Will this require a permit?
Only your local authority having jurisdiction can answer that.
 
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Old 01-15-16, 04:07 PM
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OK, I bought the microwave today. It wasn't set up to be hard wired like I'd expected. It has a standard 3-prong plug. The instructions say I need an outlet in the cabinet above the microwave.

Can I just wire this new outlet from the current counter-top outlets? After all, that's where my old microwave is plugged in, and I won't be using it anymore.
 
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Old 01-15-16, 04:10 PM
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The countertop circuit cannot power the over the range microwave. It needs a dedicated circuit.
 
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