squirrelslayer
Member
Ok here goes, I apologize in advance for any rambling I may do.
Have a 112.5 KVA transformer, 3?, 408 delta primary 208y/120 secondary.
Transformer is currently supplying a 208y/120, 3?, 225 rated 42 space panel with a 200 amp breaker.
This panel is then suppling a MLO sub-panel that has 100 amp 3 pole breaker at the main.
Client wants an additional panel as these two are full, this new one is the same as the exsisting main but with 30 spaces.
Client wants it done fast, fast would be protect the 30 space new sub-panel with a 100 amp 3 pole breaker much the same as the 18 space one is now.
1. I'd like to keep the future in mind and put in a 200 amp feed through breaker at the bottom of the exsisting main bus or feed through lugs at the top bus and leave the 200 amp breaker there already alone. Cheaper that way to.
2. Or can I tap into the secondary side of the transformer to supply the new 30 space panel and protect it with its own 200 amp MB and still stay within 240.21(c)(2)? Distance between the two big panels would be about 8' max.
Either of those last 2 options would require more down time for devices on the circuits during the change over meaning doing it a night.
The load in the new 30 space panel is all single phase 120v with 6 ea. 35amp circuits and 3 ea. 20 amp for now, don't know what the future brings to it. His plan is the fastest, however I know he'll have me back out down the road redoing it. More money thats for sure but a pain in the butt at this site.
Any thoughts you have that I could run by the client would be great.
Have a 112.5 KVA transformer, 3?, 408 delta primary 208y/120 secondary.
Transformer is currently supplying a 208y/120, 3?, 225 rated 42 space panel with a 200 amp breaker.
This panel is then suppling a MLO sub-panel that has 100 amp 3 pole breaker at the main.
Client wants an additional panel as these two are full, this new one is the same as the exsisting main but with 30 spaces.
Client wants it done fast, fast would be protect the 30 space new sub-panel with a 100 amp 3 pole breaker much the same as the 18 space one is now.
1. I'd like to keep the future in mind and put in a 200 amp feed through breaker at the bottom of the exsisting main bus or feed through lugs at the top bus and leave the 200 amp breaker there already alone. Cheaper that way to.
2. Or can I tap into the secondary side of the transformer to supply the new 30 space panel and protect it with its own 200 amp MB and still stay within 240.21(c)(2)? Distance between the two big panels would be about 8' max.
Either of those last 2 options would require more down time for devices on the circuits during the change over meaning doing it a night.
The load in the new 30 space panel is all single phase 120v with 6 ea. 35amp circuits and 3 ea. 20 amp for now, don't know what the future brings to it. His plan is the fastest, however I know he'll have me back out down the road redoing it. More money thats for sure but a pain in the butt at this site.
Any thoughts you have that I could run by the client would be great.
