Building service

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jimmac49

Member
Location
NY & CT
We have a 60% design for a large industrial shop. The main service consists of 2 3MVA transformers each on feeding a 5000 amp main breaker in seperate enclosures. Each breaker feeds a section of bus with a N.O. tie breaker mid way in the bus. I see some problems with this arrangement. It makes more sense to me to put the tie breaker between the 2 mains and interlock them so on 2 of the 3 breakers can be closed at a time. Any thoughts or suggestions are appreciated.

Jim
 

zog

Senior Member
Location
Charlotte, NC
We have a 60% design for a large industrial shop. The main service consists of 2 3MVA transformers each on feeding a 5000 amp main breaker in seperate enclosures. Each breaker feeds a section of bus with a N.O. tie breaker mid way in the bus. I see some problems with this arrangement. It makes more sense to me to put the tie breaker between the 2 mains and interlock them so on 2 of the 3 breakers can be closed at a time. Any thoughts or suggestions are appreciated.

Jim

It would be key-interlocked either way. The M-T-T-M arrangement (Tie bus) allows for expanding later, or adding a sparing transformer. If you dont think this is necessary than go with your M-T-M design, saves the cost of another Tie Breaker. We build custom switchgear lineups and have hundreds of subs like these in stock from all manufactures.
 
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