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Amperage Flow

Would 12 ga wire allow a microwave to draw more amperage than 14 ga wire? I had a microwave on a shared 15 amp circuit with 14 ga wiring. Whenever something else was switched on the breaker tripped. I ran 12 ga wire to the panel to a dedicated outlet for the microwave but only used a 15 amp breaker. The microwave is drawing 14 amps and is tripping the breaker. I will put a 20 amp breaker in the panel for this but my question is why didn't the breaker trip when it was wire with 14 ga?

Thank You,

Re: Amperage Flow

While increasing the wire size for the whole branch circuit and going to 20A might solve the problem... all major appliances should be on a dedicated circuit. A Microwave included. The installation instruction will tell you this. I believe it calls for at least a 15A, but a 20A is better. It you're out of spaces in the panel, you can get a double breaker while allows 2 branch circuits in a single space.

Re: Amperage Flow

I believe the 14 gauge wire added enough resistance to the circuit that the microwave was running at less than full capacity and would not trip the 15A breaker, unless another load was added.

The heavier #12 allowed the MW to trip the 15A breaker. I wonder why you didn't use a 20A?

If you have had a motor load (instead of the MW)you could have burned it up because of the voltage drop on #14.

Good Luck from Columbiana, Alabama
Maurice Turgeon, http://thesemi-retiredelectrician.com

Re: Amperage Flow

I agree with Semi Retired. A microwave that draws 14 amps should be on a 20 amp breaker. you don't want a continuous draw in excess of 80% of the rated amperage.


Re: Amperage Flow

Thank you guys for answering my questions right away. My mind will now be at ease when I change the 15 amp breaker to a 20.

Thanks once again,


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