200amp panel

Fire238

Member
Location
NY
Occupation
Electric
Question, I have a customer who has a single phase 400-meter channel spilt into 2 -200amp panels. At pole transformer he is poling 305amps on each leg. In each panel on leg A is 175amps and leg B 175amps. how is this not tripping out his 200amp main breaker? is load is 240V.
 

Carultch

Senior Member
Location
Massachusetts
Question, I have a customer who has a single phase 400-meter channel spilt into 2 -200amp panels. At pole transformer he is poling 305amps on each leg. In each panel on leg A is 175amps and leg B 175amps. how is this not tripping out his 200amp main breaker? is load is 240V.
A 200A breaker by design, is meant to only trip if there is more than 200A on at least one of its poles. Could be >200A on both poles, or could be >200A on just one pole. The current is not additive, but rather each pole independently determines if it should trip.

175A on each line of a split-phase system, is not 350A at 240V. It's the equivalent total power of 350A at 120V, but it isn't 350A anywhere. It's still 175A at 240V.
 

Fire238

Member
Location
NY
Occupation
Electric
A 200A breaker by design, is meant to only trip if there is more than 200A on at least one of its poles. Could be >200A on both poles, or could be >200A on just one pole. The current is not additive, but rather each pole independently determines if it should trip.

175A on each line of a split-phase system, is not 350A at 240V. It's the equivalent total power of 350A at 120V, but it isn't 350A anywhere. It's still 175A at 240V.
Thanks, I was thinking the 200amp braker was a total it could see. At my transformer I have 350 at each leg, which was sized for 400amps at 120v
 
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