How much current does a refrigerator use?

[Marvin_the_Martian]

@Johnny_L.A

The electrician said the microwave oven needed to have its own outlet because of the codes. He called it a ‘dedicated’ outlet, but he may have been speaking colloquially. In fact, I do use both sockets.

Only built-in (“fastened in place”) microwaves need a dedicated circuit:

210.23 Permissible Loads, Multiple-Outlet Branch Circuits

The total rating of utilization equipment fastened in place, other than luminaires, shall not exceed 50 percent of the branch-circuit ampere rating where lighting units, cord-and-plug-connected utilization equipment not fastened in place, or both, are also supplied.

[Johnny_L.A]

@Dorjan

The proper term is a dedicated circuit, not dedicated outlet. A circuit can have multiple outlets, a dedicated circuit will only have one outlet, for the appliance that it’s reserved for.

@TriPolar

Thank you. Correction noted.

Noted by me as well. I just checked, and the microwave oven does have its own circuit breaker in the panel.

@Marvin_the_Martian

Only built-in (“fastened in place”) microwaves need a dedicated circuit:

IANA electrician.

[beowulff]

FWIW, our 1970’s kitchen shared a single circuit with a tester oven, coffee maker and fridge. All three could operate if the fridge was running when then other two were turned on, but if the compressor came on when the toaster and coffee maker were running it would often trip the breaker. When we remodeled, I added another circuit to solve that issue.

[aceplace57]

My 1500W generator noticably speed up whenever the fridge compressor cycled on.

I could run tv, a few lights and the fridge during power failures. I unplugged the fridge before running the microwave or coffee pot.

That’s why I finally installed a 14k whole house gen.

[That_Don_Guy]

@Common_Tater

Kill-A-Watt meters are great, they work really well for stuff like this, albeit maybe not for brief peak load when spooling up. I agree 8 amps sounds closer than 3, for peak load.

Also keep in mind, for refrigerators the compressor is not running constantly. Figure about a 33% duty cycle, something like that. Maybe closer to 50% in the summer? Circuit breakers can get “tired” too, eventually, and start to trip early.

I am just worried that the compressor will “kick in” when I am right in the middle of microwaving something, and the combination will cause the circuit breaker to pop. It is a 20 amp line, and “only” a 1000 watt microwave (8.3 A @ 120 V), so it shouldn’t be a problem.

When I first moved in, I had the microwave and refrigerator on the same line, and it never popped, but that microwave was only 900 watts. When I replaced my refrigerator, it wouldn’t fit in the old one’s spot, but my new one is going back to where the original one was.

As for the microwave being on a dedicated line, I think my house was built 30 years ago, and there are no dedicated-line 120V outlets (except for things like the clothes washer - even the dishwasher shares an outlet with the garbage disposal). The refrigerator and microwave were always meant to share a line - well, either that, or one of them was expected to share a 15 amp line with my living room, including the TV and stereo system.

[The_Librarian]

Your worst case is that a breaker wil trip?

[Carlarm]

Not a good idea to have a refrigerator or freezer on a GFCI protected circuit because the current spike when the motor starts can trip it and spoil food. I had a freezer in the garage connected to GFCI circuit that would lose power every so often. I located the GFCI outlet (regular outlets are commonly daisy chained to one GFCI outlet) and replaced it with a standard outlet, which solved the problem. In hindsight, I realize the GFCI outlet could have been rewired so other outlets connected to it were not GFCI protected.

[FinsToTheLeft]

@Carlarm

Not a good idea to have a refrigerator or freezer on a GFCI protected circuit because the current spike when the motor starts can trip it and spoil food. I had a freezer in the garage connected to GFCI circuit that would lose power every so often. I located the GFCI outlet (regular outlets are commonly daisy chained to one GFCI outlet) and replaced it with a standard outlet, which solved the problem.

This is more likely to happen with an older fridge due to worn windings leaking current to ground, so the GFCI is actually doing what it should be doing. Code in many locations requires GFCI and bypassing it violates code.

[Napier]

@Marvin_the_Martian

Also note that breakers do not trip immediately when their rating is exceeded.

Very much so indeed! As a novelty I have 1500 W incandescent light bulbs (a steal at only $14), which really brighten a room. And warm it. Nominally they draw 12.5 A at 120 V. But their resistance is proportional to the filament temperature, which at 300 K is tenfold what it is while operating at 3000 K. Their starting current, unless it’s limited by the resistance of the supply wiring, is therefore 125 A. This goes down very rapidly, almost too fast to see as the bulb brightens. It’s certainly well above 20 A, though.

In fact, if you’ve ever notice “tungsten rated” on a fuse or circuit breaker, it specifically means the device is rated to handle that brief but profound inrush for tungsten filament incandescent lamps.

Wires can briefly carry way more current than they can steady state. IIRC, 24 AWG wiring will often handle a lightning bolt of thousands of amperes. In wiring, lightning generally causes damage because of high voltage, not because of the high current.

[beowulff]

I like big bulbs and I cannot lie…

Unused 5KW. I’ve always been too scared to power it up…

[Napier]

I have a 2M/G48/17 theatre spotlight lamp rated 2KW that looks very similar, except that it is used and has significant darkening near the top of the envelope, for which reason it was retired from service. But it’s intact. I’m afraid to power it up, too.