Over the Range Microwave.


Old 07-06-08, 12:09 AM
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Over the Range Microwave.

I have an "older" home built in 1977 that currently has a hood with fan and light.

I want to replace it with a over the range micrwave. My problem is its not dedicated cuircuit. There is a kitchen light on the same circuit. Because of the layout of my house it is not feasible to put in a dedicated circuit unless i do some major demo to run a line from the other side of the house.

I have a few questions:

1.I know its supposed to be a dedicated but is it unsafe for me to install a plug on the existing circuit?

2. If i go ahead with the install is it better to get a micrwave under a certain watts limit in order to be "safer"

3. If I wanted to change the 15 amp circuit to a 20 amp circuit does that require changing anything in the wireing, or do you just change something in the electrical box.

4. Is the most that will happen is I trip the breaker if i turn the light on and the microwave? I don't have my current microwave plugged into a dedicated circuit outlet.
Old 07-06-08, 12:51 AM
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You can't change the breaker to 20 amp, the wire will melt before the breaker trips and is a fire hazard.

If you install an outlet on the existing wiring leave the breaker alone. Get a microwave at 1100 watts or less. Even with that you will probably trip the breaker if too many lights are on.

I have in the past with older homes been able to pull additional wire through the conduit that goes to the oven and extend to the microwave. Older homes are usually wired with conduit.

Before attemting to pull wire through existing conduit make sure it is possible by opening up the box for the oven outlet and take the breaker panel cover off (make sure power is off) find the conduit going to the oven and tug on the wires. Have a helper watch the wires at the oven outlet and see if they move. If they don't move then forget it, you will never be able to pull wire through.

If you do see wires move , then tie a pull string to them and pule them out. Pull them back in with additional #12 THHN wires for microwave. From oven box fish 12-2 Romex up the wall to microwave outlet
Old 07-06-08, 05:01 PM
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You should be okay using the existing circuit.
You are allowed 1800 watts on that 15 amp circuit so if you only have one light fixture, check the wattage and size your microwave accordingly.
Just make sure that there is only that one light fixture on the circuit.
Old 07-07-08, 04:59 PM
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It should be a dedicated circuit, but 1977??? Elvis was still alive. My house was built around that same era, and I notice the lights flicker slightly when the microwave either shifts gears or shuts down, so I'm in the same boat. Luckily mine is on a 20 amp circuit already. If the current 15 amp breaker handles the load, leave it be. If it doesn't, follow rich's ideas on rewiring for a dedicated one.
Old 07-09-08, 09:28 PM
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Ok... I plugged my existing microwave into the receptical I installed on the 15 amp circuit that shares several lights on the floor. ( previously the range hood was there)

it didn't trip the breaker with all the lights on and the microwave running. The light does breifly flicker when the micro kicks on.

This is the new question. Is it more of a cardinal sin.

1. To run the over the range microwave on a non dedicated 15 amp circuit


2. Run a line from my basement dedicated 20 amp laundry circuit up to the kitchen and have just the microwave and the washingmachine on the 20amp circuit.
Old 07-09-08, 09:52 PM
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I cannot advise you to do either. But I think you overestimate how hard it woudl be to run a new circuit. People who do this for a living have a million little tricks that can make this job a lot simpler than you think it would be.
Old 07-09-08, 10:11 PM
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next step

Thanks, John

Well.. my next step is to have an electricial give me an estimate.

The problem I run into is the circuit breaker is on the other side of the house in the basement.

I am sure I don't know all the tricks. I hope it won't be that hard (AKA that expensive)

And if it is I am sure I will be doing a lot of drywalling.

Old 07-09-08, 11:31 PM
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If the electrician do it right it will only need patch few very small spots of drywall don't need to tear a big slab of drywall at all.

They will carry few specal tools to get around in the finshed walls so what they been doing for long time they can able do it with very little damage to the exsting walls so case no damage to the drywalls if right on target.

Myself I done some pretty tough spots and only have to patch small peices of drywalls.


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