how many amps
- Thread starter difowler1
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- Placerville, CA, USA
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- Retired PV System Designer
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!
This is not like a motor thermal overload where the sum of the currents is important.
Tapatalk!
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.
jumper
Senior Member
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- 3 Hr 2 Min from Winged Horses
Here is a good article about trip curves and time delay of MCCBs explaining the subject.
http://static.schneider-electric.us...100-400 A Frame FA-LA/FA-FC-FH/0600DB0105.pdf
http://static.schneider-electric.us...100-400 A Frame FA-LA/FA-FC-FH/0600DB0105.pdf
- Location
- Illinois
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- retired electrician
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.
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- Lockport, IL
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- Retired Electrical Engineer
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.
kwired
Electron manager
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- NE Nebraska
Yet none were mentioned.
kwired
Electron manager
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- NE Nebraska
- Location
- Illinois
- Occupation
- retired electrician
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.
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.
kwired
Electron manager
- Location
- NE Nebraska
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.
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.
kwired
Electron manager
- Location
- NE Nebraska
- Location
- Placerville, CA, USA
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- Retired PV System Designer
I see the 201A as not being given in the form of a question even though it should have been.
Tapatalk!
Tapatalk!
He answered his own first question with "201 Yes", which actually only leaves one question left.
kwired
Electron manager
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- NE Nebraska
This is not Jeopardy
This is not Jeopardy
My thoughts exactly.
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