# Using a 110V 10Amp breaker in a 120V system

I know this is a really stupid question. The reason I'm asking is I made a little bet with my brother and I'm not sure I have to pay up.
The bet was in which system would a normal 110V 10Amp breaker blow first.
System 1 - assuming each toaster draws 1Amp and runs at 110V - the voltage on the system is 110V I plug 10 of them in, breaker is OK, plug in #11, breaker should blow
System 2 - assuming each toaster draws .5Amp and runs at 220V - the voltage on the system is 220V How many toasters can I plug in until the EXACT same breaker will blow in this system?
I appreciate your indulgence on this silly question.
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Breakers can and do withstand more than rated amperage, FOR A PERIOD OF TIME. That time depends on the breaker curve of the manufacture. When testing breakers and we want one to trip fast we will throw 8 to 10 times the rated amperage at it. Trips occur in less than a second. When measuring LTD long time delay on a breaker we look at the curve and inject ~3 times rated current value. The breaker will trip usually it take more than a minute of over load for the breaker to open. I have seen some that went closer to 3 minutes at 3 times.
All depends on what kind of breakers and who made them.
System one if you wait long enough the 11th toaster will trip the breaker eventually. System two you could get the 10 amp breaker to trip on the 21st toaster, if you wait long enough.
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Thanks, that's what I worked out mathematically also but I wasn't sure if I had it right since I expected the same amount of power (Watts I guess) to trip the breaker in both systems... looks like I do have to pay up.
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110 watt tosters wont work well :)

assuming the trip point is 10 A and the loads are .5 amp 19 will run (although it exceeds the recomended 80% max continuous load). this also assumes the load is constant.
the bread however will not become toast.
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TimPerry wrote:

Although you probably know this, it could be a tad misleading to leave some people thinking that breakers work like this and that a 10A breaker will always trip at 10A load current.
In practice, they rely on clearing overloads by using a thermal trip. As these have to lose heat to the environment, ambient temperature conditions are quite important.
At very high ambient temperatures a breaker may easily trip before its rated current - one reason for the max continuous load derating.
At the right ambient temperature a 10A breaker will trip at 10A, /eventually/. As the time/current graph is almost vertical at low overloads it could be a very long time, tens of minutes, and one with a great deal of variability. Even small changes in ambient temperature would greatly affect the time to trip.
At lower ambient temperatures, the breaker will never trip at rated current. At much lower temperatures, the breaker will never trip even with a 10%, or even higher, overload.
In the scenarios proposed, assuming the same temperatures, then the question is whether the breaker would trip with one extra toaster or two extra, in the second scenario - if it tripped in the first with one extra. The answer is that it /would/ trip with two, probably in the same sort of time. It /may/ trip with one - but it would take longer, perhaps far, far longer to do so.
Of course, as the degree of overload increases, a point will be reached when the breaker will trip no matter what the ambient conditions. In addition manufacturers are allowed tolerances. For overloads, a typical breaker will be guaranteed not to trip below a particular current and guaranteed to trip over a particular current, within a given time at a given temperature. But the actual trip current is not normally specified.
-- Sue
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i was careful to say "assuming the trip point is 10 A "
we don't know if the bet was real world or theoretical :)
we could take it a step further and try to estimate the starting current of a cold heating element vs. steady current in a hot element.
im still wondering where we are going to find 110 watt toasters,
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TimPerry wrote:

LOL I was careful to say that you probably knew.. <snip>

Specially made for the health-club market for cooking really tiny pieces of bread, perhaps?
--
Sue

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like the elves say to Santa Clause... be careful, its a jingle out there

the George Forman high efficiency toaster?
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TimPerry schrieb:

Hello,
they may work well if the slices are small enough. But a good bread does not need to be toasted before eating.
Bye
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