I am working on a UPS project. A UPS in building A is next to the 480v substation. The ups is being fed by the 480 volt substation in building A and will be the source of critical power feeding a transformer in building B. The transformer is a 480V Delta to 208V/120V Y. The distance of the feeder is 400 feet, 100 ft. in building A and the rest in building B. There is an OCPD upstream at the UPS in building A and a disconnect on the primary of the transformer in building B. Both buildings have multiple Double ended substations fed by 2 ea. 12.4kv feeders from different 69kv lines. The buildings are joined by egress bridges and common hall ways, essentially 2 separate buildings. Grounding of the 2 buildings has been addressed by bonding them together. My question is a code concern about the 480 volt substation in building A feeding the critical power in building B.
I did find a code section that would address service conductors, 230.3, yet I am concerned about the gray area of the building attachment issue: bridge and hallway as claim that the buildings are treated as one building and the fact that building B has many of its own substations.
1.) I am concerned about the substation transformer in building A and the possibility of a potential difference with the transformer in building B due to the different HV feeders and possible phase angle difference.
2.) This issue of mixing 2 individually / separately derived systems in the same environment is a code concern.
3.) Fire safety issues, no disconnect would be required at the exterior of the building because it is considered a feeder.
However if someone else has additional information with respect to this design or has had an opportunity to work on a similar design, please chime in!
I apologize for any misconception about the installation design, feel free to post for clarification.
Thank you,
M P L
Electrical / Mechanical Engineering Support Lead
New Jersey Licensed Electrical Contractor
WJHTC FAA
I did find a code section that would address service conductors, 230.3, yet I am concerned about the gray area of the building attachment issue: bridge and hallway as claim that the buildings are treated as one building and the fact that building B has many of its own substations.
1.) I am concerned about the substation transformer in building A and the possibility of a potential difference with the transformer in building B due to the different HV feeders and possible phase angle difference.
2.) This issue of mixing 2 individually / separately derived systems in the same environment is a code concern.
3.) Fire safety issues, no disconnect would be required at the exterior of the building because it is considered a feeder.
However if someone else has additional information with respect to this design or has had an opportunity to work on a similar design, please chime in!
I apologize for any misconception about the installation design, feel free to post for clarification.
Thank you,
M P L
Electrical / Mechanical Engineering Support Lead
New Jersey Licensed Electrical Contractor
WJHTC FAA
