how many amps

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difowler1

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I was wondering how many amps would normally cause a 200 amp main breaker to trip. 201 yes. But is that 201 on each leg or 101 on each leg?
 
Ideally it is something a little higher than 201on any single leg, regardless of what the current on the other leg is.
This is not like a motor thermal overload where the sum of the currents is important.

Tapatalk!
 
difowler1 said:
I was wondering how many amps would normally cause a 200 amp main breaker to trip. 201 yes. But is that 201 on each leg or 101 on each leg?
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If it's rated at 200 A, then 200 A it is. Unlikely that 201 A would trip it. And if it did, you'd need a calendar rather than a stop watch to get the time to trip.
 
The breaker standard will permit a 200 amp breaker to carry 268 amps forever without tripping. At 270 amps it must trip within 60 minutes.
 
difowler1 said:
But is that 201 on each leg or 101 on each leg?
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I infer you are talking about a single phase service. 201 amps flowing through the breaker means that 201 amps are on Phase A and 201 amps are on Phase B, for a "total" (I hate using that word in this context) of 201 amps. It is the same current that flows out of the breaker on one leg and back into the breaker on the other leg.

 
It all depends on the conditions.

Anyone who says it will carry its rated amperage indefinitely has never been in charge of keeping the power on to a stage at an outdoor event with a fully loaded panel in 100 degree temperatures.
 
jap said:
It all depends on the conditions.

Anyone who says it will carry its rated amperage indefinitely has never been in charge of keeping the power on to a stage at an outdoor event with a fully loaded panel in 100 degree temperatures.
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Ambient temperature does factor into the trip time. Some of the previously mentioned loads and times do also have an ambient temp that goes with those ratings.
 
kwired said:
Ambient temperature does factor into the trip time. Some of the previously mentioned loads and times do also have an ambient temp that goes with those ratings.
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Yet none were mentioned.
 
kwired said:
True.

I believe most of those tests are done at 40 deg C.
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Yes, the breaker testing is done at 40?C (104?F), but with a single breaker. The fact that the breakers are tested without heat from other breakers in a common panel is the very reason for the 80% of rating rule. The breaker testing is at 100% of its rating.
 
I may be wrong, but without getting too technical,

It seems the OP was just trying to get a grasp on the common misconception that 100 amps on A Phase + 100 Amps on B Phase = 200 Amp Breaker that is at or near trip point.

Not so, It's only about half, or a little over half the way there.

The 200 Amp Breaker has the capability of handling 200 Amps per Phase.
 
jap said:
I may be wrong, but without getting too technical,

It seems the OP was just trying to get a grasp on the common misconception that 100 amps on A Phase + 100 Amps on B Phase = 200 Amp Breaker that is at or near trip point.

Not so, It's only about half, or a little over half the way there.

The 200 Amp Breaker has the capability of handling 200 Amps per Phase.
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Yes, but he also mentioned a situation of 201 amps on a 200 amp breaker. It can carry more then 200 amps, how much more and for how long depends on other factors and some of those have been mentioned. Or it could even trip on a load under 200 amps in a high ambient temperature, but time will also be a factor in that situation.
 
kwired said:
Yes, but he also mentioned a situation of 201 amps on a 200 amp breaker. It can carry more then 200 amps, how much more and for how long depends on other factors and some of those have been mentioned. Or it could even trip on a load under 200 amps in a high ambient temperature, but time will also be a factor in that situation.
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You can tell by the way he posed the question that he was simply inquiring if the breaker is looking at a combined total of both legs added together or each leg individually.
 
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