malachi constant
Senior Member
- Location
- Minneapolis
Hi all,
Question on 700.3(F) "Temporary Source of Power for Maintenance of Repair of the Alternate Source of Power".
Application is a new facility where the building service is classified under Article 701 Legally Required, and the distribution includes a smaller Article 700 Emergency (life safety) ATS. The generator contains two output breakers, an 800A that feeds a service-entrance rated transfer switch which then feeds the facility main panel. The second output breaker is 200A and directly feeds the emergency life safety ATS. No issues yet.
Per 700.3(F), for the times when the generator is out of service (planned maintenance or unexpected failure) there is a docking station to allow for connection of a portable generator. The docking station is sized at 800A and is connected between the 800A generator output breaker and the emergency input of the 800A ATS. The design intent is for the portable generator to provide not just emergency life safety backup, but also to back up the entirety of the building (it is a 911 center).
The question has come up if the docking station needs to have two separate output breakers (800A and 200A) in order to maintain independence of 700 and 701 systems. The two trains of thought are:
1. The docking station is required by 700.3(F), and nothing within 700.3(F) requires separation of systems. One could argue this interpretation makes sense that as this is a "backup of a backup" the requirements are less rigid.
2. The docking station is required by 700.3(F) but as it is part of Article 700 it is not exempt from related requirements within 700. That "an emergency source is an emergency source" regardless of whether it is temporary or permanent.
Trying to think through all angles, 700.3(F) points to 700.12: "Transfer of power between the normal power source and the emergency power source shall be in accordance with 700.12." 700.12 speaks of "transfer" in terms of: must happen within 10 seconds, and generator must automatically start and automatically transfer. (As well as some language about "transferring" between fuel supplies which doesn't apply.) I don't see anything related to "transfer" in 700.12 that disallows the original solution.
Alternate solutions if the second train of thought is followed:
A. Instead of a docking station with two output breakers one could install a standard docking station that feeds an emergency distribution service with breakers in two separate vertical sections.
B. Instead of a docking station with two output breakers one could install two separate docking stations, one for the 800A legally required and one for the 200A emergency life safety.
Anyone have thoughts or experience with this? My "common sense" approach had always been (1) makes sense code would want an temp generator to back up em lights during planned maintenance, good job code; (2) might as well ask the Owner since they are paying for a docking station, did they want to upgrade to a larger one to back up the whole building (whether during planned maintenance or extended utility outage). And until now never once thought twice about the way I've been doing it for the last six years or so. I interpret along the "first train of thought" but am being exposed to the second and looking for input from others. Always learning!
Question on 700.3(F) "Temporary Source of Power for Maintenance of Repair of the Alternate Source of Power".
Application is a new facility where the building service is classified under Article 701 Legally Required, and the distribution includes a smaller Article 700 Emergency (life safety) ATS. The generator contains two output breakers, an 800A that feeds a service-entrance rated transfer switch which then feeds the facility main panel. The second output breaker is 200A and directly feeds the emergency life safety ATS. No issues yet.
Per 700.3(F), for the times when the generator is out of service (planned maintenance or unexpected failure) there is a docking station to allow for connection of a portable generator. The docking station is sized at 800A and is connected between the 800A generator output breaker and the emergency input of the 800A ATS. The design intent is for the portable generator to provide not just emergency life safety backup, but also to back up the entirety of the building (it is a 911 center).
The question has come up if the docking station needs to have two separate output breakers (800A and 200A) in order to maintain independence of 700 and 701 systems. The two trains of thought are:
1. The docking station is required by 700.3(F), and nothing within 700.3(F) requires separation of systems. One could argue this interpretation makes sense that as this is a "backup of a backup" the requirements are less rigid.
2. The docking station is required by 700.3(F) but as it is part of Article 700 it is not exempt from related requirements within 700. That "an emergency source is an emergency source" regardless of whether it is temporary or permanent.
Trying to think through all angles, 700.3(F) points to 700.12: "Transfer of power between the normal power source and the emergency power source shall be in accordance with 700.12." 700.12 speaks of "transfer" in terms of: must happen within 10 seconds, and generator must automatically start and automatically transfer. (As well as some language about "transferring" between fuel supplies which doesn't apply.) I don't see anything related to "transfer" in 700.12 that disallows the original solution.
Alternate solutions if the second train of thought is followed:
A. Instead of a docking station with two output breakers one could install a standard docking station that feeds an emergency distribution service with breakers in two separate vertical sections.
B. Instead of a docking station with two output breakers one could install two separate docking stations, one for the 800A legally required and one for the 200A emergency life safety.
Anyone have thoughts or experience with this? My "common sense" approach had always been (1) makes sense code would want an temp generator to back up em lights during planned maintenance, good job code; (2) might as well ask the Owner since they are paying for a docking station, did they want to upgrade to a larger one to back up the whole building (whether during planned maintenance or extended utility outage). And until now never once thought twice about the way I've been doing it for the last six years or so. I interpret along the "first train of thought" but am being exposed to the second and looking for input from others. Always learning!