Unless this is a microwave hood it does not require a dedicated circuit.

 

Ah, ok. I've read that code now requires separate circuits for each. Even if not, is 20A breaker, with wiring that is probably 70 years old (1950's) safe for both refrig and micro? It was brought up to 200 amp service about 12 years ago, but I don't know that that included replacing all the wiring to the outlets. I've assumed not, given what I've seen in replacing light bulb fixtures, etc.

Thanks,
Robert

 

How are the 2 outlets wired? Separate cables to the panel or looped from 1 to the other?

 

That I don't know, at this point, to be honest. But will make a point of finding out. After posting this, though, I realized I was envisioning separate pairs from each to the circuit breaker, i.e. parallel, when probably it might be that they're in series, and a single pair back to the breaker.

Can you tell me what might be involved in each case?

Thanks,
Robert

 

If one cable feeds both as I suspect, you must run a new cable to get a 2 nd circuit. If there are not 2 hot wires on 1 breaker, this is the only way.
If the wire (cable) does not have a ground, you do need a new cable. As to 1 cable carting both refrigerator and microwave, it probably can if it is a standard refrigerator not a built-in type such as sub zero.

 

Ok, got it, thanks. In that case, likely being one cable for both, I'd call in an electrician (just not a good time for that now). It is a standard refrigerator, so glad to hear two opinions that the circuit can handle both.

Thanks,
Robert

 

The NEC doesn't require a countertop microwave or refrigerator to be dedicated circuits.

 

You might be assuming that refrigerators take a lot of electricity to run. Fact-check that

I generally encourage people to think about the heat that an appliance makes to gauge its energy use. However, a fridge is a weird one because it is a heat pump. It is not creating that heat from electricity, it is pumping heat that was inside the fridge. As such, it makes 400-1000W of heat for only 100W actually used. Heat pumps are "over unity" like that. One guy describes them as "a physics cheat code".

Fridges do have a 10-ish amp startup surge, but only for a fraction of a second. Then they settle out to a draw in the 100 watt range. The breaker won't care if that startup surge happens while the microwave is pulling 15A. 25A for <1 second is well within the "green zone" of a 15A or 20A breaker.

 

You might be assuming that refrigerators take a lot of electricity to run. Fact-check that

I generally encourage people to think about the heat that an appliance makes to gauge its energy use. However, a fridge is a weird one because it is a heat pump. It is not creating that heat from electricity, it is pumping heat that was inside the fridge. As such, it makes 400-1000W of heat for only 100W actually used. Heat pumps are "over unity" like that. One guy describes them as "a physics cheat code".

Fridges do have a 10-ish amp startup surge, but only for a fraction of a second. Then they settle out to a draw in the 100 watt range. The breaker won't care if that startup surge happens while the microwave is pulling 15A. 25A for <1 second is well within the "green zone" of a 15A or 20A breaker.

I was, and am now enlightened

Thanks for that pointer, and additional explanation, reassurance on current levels.

Yeah, it is kind of unique, that more W is generated, then consumed, although as mentioned, not all electrically.

Thanks,
Robert

 

The ultimate goal here should be a separate branch circuit for the refrigerator receptacle.

A microwave oven is a "high current draw" appliance. Thus it is not guaranteed that the momentary higher power draw when the refrigerator kicks on during operation of the microwave will not trip the breaker. It is much better for a refrigerator to have its branch circuit compared with share a circuit in a manner requiring management (manual discipline and attention) to protect against spoiled food..

OT: I only wish that a receptacle with no ground fault circuit interrupter protection be provided for the refrigerator but we are stuck with the NEC and other applicable codes as they stand.

 

Thanks for the note of caution, and that will be the intention - update each to separate circuits. I'm planning on putting an electricity monitor on the refrigerator, to monitor it's peak amps, before making a decision on adding in the microwave on the same branch. I initially purchased a 'Kill A Watt', but it doesn't have peak readback (especially important, since the outlet is behind the refrigerator, so I'll not be able to see the meter). I'd welcome a recommendation for a meter that does.

Robert

P.S. I didn't quite get your comment about wishing a receptacle with no ground fault circuit interrupter, but curious, if you wanted to add any additional explanation.

 

Ended up getting this meter:

Upgraded Brighter LCD Display Night Vision Power Meter Plug, Power Consumption Monitor Energy Voltage Amps Electricity Usage Monitor, Overload Protection, 7 Display Modes for Energy Saving, Watt Meter - - Amazon.com

Upgraded Brighter LCD Display Night Vision Power Meter Plug, Power Consumption Monitor Energy Voltage Amps Electricity Usage Monitor, Overload Protection, 7 Display Modes for Energy Saving, Watt Meter - - Amazon.com

www.amazon.com

showed a peak of 856 watts@116 volts for the refrigerator, so about 7.4 Amps. 99% of the time, it was in the 200 W area. But considering peak, and the 20 Amp breaker, 80% rated ... would allow about 8 amps from a microwave, during refrig infrequent surges. I don't think that is very doable, except the least powered micros out there.

Robert