A/C and Microwave

sgtlm17 · 03-27-2016, 11:51 PM

Today I discovered my power center has one 20 amp breaker. Both my convection microwave and A/C are on this one circuit. Is this a problem. Is this because it is a convection microwave. I always thought these two items should have their own breaker. On the box it's labeled A/C. There is a 15 amp breaker at bottom that is labeled microwave that is not used. Any input?

2016 Forester GTS 2801QSF

Witch Doctor · 03-28-2016, 05:13 AM

You are correct they should not be on the same breaker. I would separate them. It really makes no difference if it a microwave oven or not. The only thing connected to the A/C breaker should be the A/C. Not sure how they wired it either through a junction box, or just put two wires to the same breaker which is definitely a NO NO.

sgtlm17 · 03-28-2016, 06:32 AM

Yes I agree I thought it was odd. I will have to take a look at the wiring on Wednesday.

sgtlm17 · 03-30-2016, 06:06 PM

Ok took a deeper look. I have one 20 amp breaker. It's has 12ga wire and runs only microwave. It is labeled air conditioner in the box.
I have no other 20 amp breakers. The air conditioner / heat pump is connected to a 15 amp breaker with 12ga wire. It is labeled microwave.
Now obviously the installer mixed up the only two 12ga wires when connecting and is only a five minute fix to switch wires putting AC on the 20 amp breaker labeled air conditioner and the microwave on the 15 amp breaker labeled microwave. BTW I have run heat pump extensively and it does not trip 15 amp breaker but have not tried the AC. The is the microwave uses 12ga wire so it's safe to put it on the 15 amp breaker that's labeled microwave. My question is why use 12ga wire for the microwave if it was suppose to go to 15 amp breaker? I have the convection microwave will 15 amps be enough? Anybody with convection microwave please check and tell me if it's using a 15 amp or 20 amp in your rig.

bob dirt · 03-31-2016, 01:32 PM

My microwave/convection oven is on a 15 amp breaker. Usually 14 gauge wire is on a 15 amp breaker in residential and commercial applications. 20 amp breakers protect 12 gauge wire. The heat pump won't pull as many amps in the winter as it does when it's hot out. The refrigerant will be a higher pressure then and will make the compressor running amps run closer to the listed full load amp rating. 15 amp breaker may not work for it in the summer.

sgtlm17 · 03-31-2016, 01:46 PM

Thank you for replying. Yes I'm putting the a.c. on the 20 amp. I was pretty sure conv/micro will be fine on the 15 amp. Even though they did wire the micro with 12ga for a 20amp breaker.

Witch Doctor · 03-31-2016, 01:48 PM

Quote:

Originally Posted by sgtlm17

Yes I agree I thought it was odd. I will have to take a look at the wiring on Wednesday.

Your A/C should be on a 20 amp breaker, and I would think that the microwave could be on 15 amp. If you trip the breaker using it just change it to a 20 amp breaker to...

sgtlm17 · 03-31-2016, 04:56 PM

Switched the wiring today. Took seven minutes. AC / Heat Pump on 20 amp and convection / microwave on 15 amp. Tested and all works great.

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