luckylerado
Senior Member
- Location
- Lake of the Ozarks
Looking at a set of drawings and I have some concerns about the way the distribution system is layed out. Please follow my thinking and weigh in before I take this back to the EE.
Detail below:
480V primary 150KV tranasformer
208V secondary
3 phase
300 amp Primary OCP
100 amp MCB panelboards with #3 THHN feeder
1. I do not believe that tap rules apply in this scenerio becasue these are feeders from the secondnary side of a transformer therefore 240.21B does not apply looking instead at 240.21C
2. I do not believe that 240.21C(1) applies becasue these are 4 wire feeders.
3. 240.21C(2) can apply when less than 10' and ampacity of the secondary conductor is not less than the OCP rating at the MCB panelboard. 240.21C(3)(4)and (5) do not apply in this installation.
4. 240.21C(6) can apply when 25' or less. Secondary ampacity is calculated (480/208)(100)=230 ampacty of secondary conductor.
5. No complaint method is available over 25' without secondary OCP
Detail below:
480V primary 150KV tranasformer
208V secondary
3 phase
300 amp Primary OCP
100 amp MCB panelboards with #3 THHN feeder
1. I do not believe that tap rules apply in this scenerio becasue these are feeders from the secondnary side of a transformer therefore 240.21B does not apply looking instead at 240.21C
2. I do not believe that 240.21C(1) applies becasue these are 4 wire feeders.
3. 240.21C(2) can apply when less than 10' and ampacity of the secondary conductor is not less than the OCP rating at the MCB panelboard. 240.21C(3)(4)and (5) do not apply in this installation.
4. 240.21C(6) can apply when 25' or less. Secondary ampacity is calculated (480/208)(100)=230 ampacty of secondary conductor.
5. No complaint method is available over 25' without secondary OCP
