Home was built in Upstate NY in 2003. In the kitchen, refrigerator, dishwasher, and range DO have their own circuits. Now comes the "fun" part. :(

I ordered a new over-the-range 1000 watt microwave, Samsung Model. According to the specs:

Power Source 120V/60 Hz

Amp Circuit 14.5 A

Power Consumption (Microwave) 1700 W

The issue comes from this: presently, the existing exhaust hood is "double-wired" on a 15am circuit with the gas furnace. (Which is new btw, it was replaced in 2018.) I am assuming this is a BAD IDEA to use this circuit for the new microwave.

Assuming I am trying to NOT pull new wire, (I don't have room in the 200amp service anyway), the only other outlet(s) are next to the range but close enough that I COULD run the plug from NEW microwave to this wall outlet. This is a 4-plug outlet on a 20amp circuit, but shares this circuit with our bonus room. This bonus room houses my girlfriend's office, and just off top of my head has a 23" monitor, laptop computer, and inkjet printer plugged into the wall.

I am open to ideas here. :( This is my first home, I am finding more and more wrong that our inspector missed every year we are in it. Thank you in advance for any advice on this.

Bottom line, would it be safe to plug the overhead NEW microwave into that 4-port wall outlet? I will cover the other 3 to NOT USE if I have to.

P.S. microwave model is: https://www.samsung.com/us/home-appliances/microwaves/over-the-range/2-1-cu--ft--over-the-range-microwave-with-sensor-cooking-me21r7051sg-aa/#specs

  • Why do you think the inspector missed anything all that is required are the 2 circuits for the counter top appliances and your refrigerator can be on that circuit as well as the igniter for a gas range. Now the furnace with the fans unless part of the hvac system would be wrong. Look at the cord on the microwave if the prongs are parallel the mfg designed it to be on a 15 amp circuit.
    – Ed Beal
    Apr 17 '20 at 22:29
  • Range is electric, not gas and in it's own circuit. What I found was as I posted, the exhaust above the range is on the same 15amp breaker as the furnace. That can't be right? Refrigerator, dishwasher are also both on their own. I understand above range microwave is a "new idea" but I'm asking what I can do here? Apr 17 '20 at 22:39
  • What makes you think the service has no capacity left here? Also, does that 4-plug outlet serve kitchen countertop space? Apr 18 '20 at 0:05
  • @threephaseEel just looking at the existing SquareD panel, there is no available breaker spots. Yes, the 4 panel outlet services the kitchen, right now only a toaster oven (small). But it's sharing an entire living room on same 20amp circuit that serves as my gf's office. I was worried that another 1700 watts on that is too much. Apr 18 '20 at 15:35
  • @JohnUpstateNY -- it sounds like you need a bigger panel (or a big subpanel) then :) Apr 18 '20 at 18:24

The 4-outlet is on a 20A circuit, the new microwave uses ~14A, which gives you about 6A for the bonus room. The microwave will only be pulling the heavy load (MW) only occasionally. I would use the 4-outlet the way you described, with the other outlets taped over. The original exhaust-furnace circuit at 15A does not have the capacity to carry the MW load.

  • Without more information you do not know if the load is two large exhaust fans are a Tiny load , most furnace fans are fractional horsepower so with the provided info we don’t know but what we do know the hvac circuit for the furnace is supposed to be dedicated exhaust fans can be included especially if there is make up air to maintain a balance.
    – Ed Beal
    Apr 18 '20 at 1:14
  • The current exhaust fan/furnace is 15A circuit, The new MW by itself uses 1700 Watts (15A). Furnace fans, HVAC are not tiny load - probably 4-5A, which combined with the 14A MW is too much for the 15A circuit . Of the available choices and not running a new circuit, the 20A is the only one available and this is what the OP is asking. Apr 18 '20 at 2:37
  • 1
    As the new code is a dedicated circuit for a microwave with a 20amp circuit, I think I'm going to play it safe, spend the money and have a new line run. I have quotes coming this week. Thanks all for the advice. I just want to be safe. Apr 18 '20 at 16:26

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