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Old 08-05-2019, 11:08 AM   #1
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Shouldn't the breaker trip?


Hello all,

Not completely new to electrical, but typically sway from it when it involves working in the main panel to the house.

My wife and I are first time homeowners; been in this house for about 2 years. This past weekend, nosing around the panel, we noticed that our refrigerator is on the same circuit as two outlets above the kitchen counter. One of the outlets is GFCI. The circuit is a 120 volt-20 amp. We have two appliances plugged in, one in each outlet. The draw is as follows:

Fridge: 7.1 amps 115 VAC (dont have wattage for this)
Toaster: 6.25 amps 120 volt 750W
Toaster oven: 15 amps 120 volt 1800W

Obviously, those numbers exceed the 20 amp circuit as well as their combined wattage. So my question is how come the circuit breaker isn't tripping when I run the toaster and toaster oven at the same time, knowing the fridge is constantly pulling amps too?

Thanks in advance.
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Old 08-05-2019, 12:01 PM   #2
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Re: Shouldn't the breaker trip?


Circuit breakers have trip curves, and will allow for an overcurrent condition on an inverse time based basis. The curves are averaged based on manufacturer's testing. As an example, you could pull 24 amps for 2 hours, 22 amps for 4 hours before the breaker trips.


Also, a refrigerator isn't always running. Sometimes it's cooling, sometimes it's defrosting, and sometimes it's not using any power at all.
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Old 08-05-2019, 01:05 PM   #3
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Re: Shouldn't the breaker trip?


LawnGuyLandSparky,

Thank you for that info. I did not know that about refrigerators. I assumed they were constantly drawing.

Also, thank you for the explanation re: the breaker. Now I know.

Thanks again.
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Old 08-05-2019, 02:06 PM   #4
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Re: Shouldn't the breaker trip?


a refrigerator is not constantly 'running', the compressor only kicks on when the temperature rises and the thermostat tells it to, probably running 10minutes out of every hour... also, the amp/wattage ratings on many appliances are the 'max' rating, and not necessarily indicative of what is 'actually' happening at any given time.

as for the toaster, and the toaster oven, the toaster may operate at a constant 'amperage' when powered on, but the toaster oven may only run 1/2 of it's amperage, depending on the TEMP setting you are using...

remember that BREAKERS are designed and rated to protect the WIRING against overheating, NOT to protect the appliances powered by them, and the breaker is not designed to 'instantly' trip just because a sudden amperage exceeds the 20amp rating, but more of a 'constant' amperage/heat overload... meaning that it may take some time for the breaker to trip, even if there is more than a 20amp pull, especially if only for a short moment.

two heating elements, such as the toaster and the toaster oven, may draw a max of 1500 watts each, or 3,000 watts at the same time, which equals about 25amps at 120volts... but it's doubtful that each are going to their maximum power, even though they may be designed to do so, if needed.
If the fridge doesn't kick on while these two are heating, then it's unlikely the breaker will trip. If the fridge is already running when the two heating devices are then powered, the compressor has already hit it's maximum, and probably all three still won't cause the breaker to trip.

One other thing. If the wiring between the breaker and the outlets is actually a larger size than is required for 20amp circuits, then the wiring will take much longer to get hot, which is just fine, as the breaker is designed to protect wires that overheat, not ones that just get warm, no matter how many 'amps' are being used.

All that being said, the breaker may trip in the future, even will all things the same. Breakers do wear with time, become weak, and eventually start tripping more often... they have become 'overly sensitive' and may need to be replaced.

This happens a lot a campgrounds where the 30amp RV breaker is flipped on and off VERY frequently, as campers leave and new campers arrive. Replacing the breaker with a new 30amp one usually solves aggravating 'tripping' breaker issues.


: )
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Old 08-05-2019, 02:21 PM   #5
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Re: Shouldn't the breaker trip?


The amps listed on appliances are the max amps it can draw. On a toaster, it will be that amperage whenever it is on.

For anything with a motor, there is starting amps and running amps. Starting amperage is always higher. But it is brief. And as @LawnGuy sparky stated, breakers account for this.

Also, that is why the NEC wants there to be certain kitchen appliances on their own circuit. That way, when a microwave starts, and you have a toaster going, you won't blow a circuit. The microwave should be on it's own circuit.

I have my toaster, blender and under cabinet lights plugged into the same outlet. The blender and toaster are both high amp draws. But, how often do you have both running at the same time? On my other circuit, I have my coffee make, espresso make, kitchen aid mixer and hot water pot all plugged in. All are 15 amp rated products. But, even if I had them all running at the same time, they probably wouldn't blow the circuit.

If you look at your panel again, the main breaker is probably 200 amps. Say there are 20 circuits in it. And you have an electric dryer (30 amps), an electric range (60 amps), a hot tub (50 amps) and an electric water heater (40 amps). Those 4 breakers alone add up to 180 amps. Does that mean that you only have 20 amps to spare for your other needs?

Of course not, you have 16 other available slots.

The NEC accounts for there to be more breaker amps than the main breaker amps. Because you probably will never ever have everything plugged in, turned on full, and running at the same time.

Just a bit more info for your entertainment.

Or in other words, what @NCmountainCabin was typing when I was typing.
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Last edited by ktownskier; 08-05-2019 at 02:23 PM.
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Old 08-05-2019, 04:00 PM   #6
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Re: Shouldn't the breaker trip?


Thank you all for replies and info. First day, first post, and I've received, IMO, a wealth of knowledge on this subject alone.

Thanks again!
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Old 08-05-2019, 06:52 PM   #7
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One other thing, what brand panel is it. If it is an older house built before the 80's, might it be one of the 2 notorious brands to not trip aka Zinsco or FPE?
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Old 08-05-2019, 06:59 PM   #8
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Re: Shouldn't the breaker trip?


But if you want the breaker to trip, that's an easy fix.
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Old 08-06-2019, 12:19 AM   #9
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Re: Shouldn't the breaker trip?


Quote:
Originally Posted by Jon714 View Post
Fridge: 7.1 amps 115 VAC (dont have wattage for this)
Toaster: 6.25 amps 120 volt 750W
Toaster oven: 15 amps 120 volt 1800W

You can figure the wattage yourself for the fridge. For example, for your toaster notice that 6.25 x 120 = 750. The numbers can sometimes be fudged depending on various things.


Those numbers are typically maximum ratings, and it would be pretty rare for all 3 to be drawing maximum at any one time. (Specifically, compressors such as in refrigerators have brief, high current draw on startup.) If they all drew maximum, it would trip your breaker. You could probably test this by setting both your heaters on max, then leaving your refrigerator door open.
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Old 08-06-2019, 12:21 AM   #10
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Re: Shouldn't the breaker trip?


Quote:
Originally Posted by Jon714 View Post
Fridge: 7.1 amps 115 VAC (dont have wattage for this)
Toaster: 6.25 amps 120 volt 750W
Toaster oven: 15 amps 120 volt 1800W

You can figure the wattage yourself for the fridge. For example, for your toaster notice that 6.25 x 120 = 750. The numbers can sometimes be fudged depending on various things.


Those numbers are typically maximum ratings, and it would be pretty rare for all 3 to be drawing maximum at any one time. (Specifically, compressors such as in refrigerators have brief, high current draw on startup.) If they all drew maximum, it would trip your breaker. You could probably test this by setting both your heaters on max, then leaving your refrigerator door open (do this while the refrig is currently not running.)
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Old 08-06-2019, 04:09 PM   #11
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Re: Shouldn't the breaker trip?


Quote:
Originally Posted by Wiredindallas View Post
One other thing, what brand panel is it. If it is an older house built before the 80's, might it be one of the 2 notorious brands to not trip aka Zinsco or FPE?
The previous owners supposedly had the panel replaced but still kept it to 100 amps. We had the panel upgraded to 200 amps and a Siemens was installed.
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