transfer switch

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mpd

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can the upstream breaker protecting a transfer switch, exceed the ampere rating of the transfer switch as long as the transfer switch is sized for the load
 
mpd said:
can the upstream breaker protecting a transfer switch, exceed the ampere rating of the transfer switch as long as the transfer switch is sized for the load
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No, it needs to be protected at it's rated ampacity along with the conductors.
 
I was looking at a coordination study that the line side breakers (normal & emergency) were increased from the original design, from what I was told the original design did not coordinate, the plan now shows a 225 amp transfer switch protected by a 400 amp breaker
 
mpd said:
I was looking at a coordination study that the line side breakers (normal & emergency) were increased from the original design, from what I was told the original design did not coordinate, the plan now shows a 225 amp transfer switch protected by a 400 amp breaker
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I kind of wondered from your OP if that was the reason you were asking. To be candid, I'm not sure that this is acceptable way to achive selective coordindation as I am only an electrician not an EE. I think there are others here more qualified that hopefully will chime in on this. It is an interesting subject.
 
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Just to cover bases, does the transfer switch have any built-in line over-current device ?
 
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