Skokian
Member
- Location
- Skokie, Illinois
Arc Flash is serious at 208 or 240 Vac Service Entrance equipment; but, is DEADLY at 480 & 600 Vac.
Anyone working on Service Entrance equipment is well advised to follow ALL of the recommendations of NFPA-70E, the Standard on Electrical Safety. See: https://catalog.nfpa.org/NFPA-70E-Standard-for-Electrical-Safety-in-the-Workplace-P1197.aspx
Moreover, if someone asks you to work on, or look at, an Electric Motor Driven Fire Pump Controller -- DON'T. Unless you are also familiar with NFPA-20 and NFPA-25 on Fire Pumps and Testing, Inspection and Maintenance of same.
Note that almost all modern Electric Drive Fire Pump Controllers are labeled and tested as being suitable for connection to utility sources capable of 100,000 Amps Short Circuit Current. While older controllers may be labeled with lower ratings, such as 30 or 50 Kampers, they are often connected to sources which have been upgraded to the 100 Kamp category.
This equipment is VERY dangerous. I have witness testing fire pump controllers in 100 Kamp and 200 Kamp test labs. The explosion shown the the above video is, if anything, understated for higher fault current utility sources. I've seen test where the door of a controller is blown open by the internal explosion and parts are ejected.
Further, note that a controller subjected to a short current above it's rated capabality is no longer save to operate or to be near since this is stand-by equipemnt which can operate at any time. The fire pump motors involved typically range form 30 Hp to 400 Hp, with the average being around 100 Hp. Motor short circuits can and DO occur, either in the motor junction box, or in the motor internal windings. Hence they become a potential source of arc flash when the controller attempts to start said motor.
This is why both NFPA-70 and NFPA-20 stress that these equipments should be worked on ONLY by suitably qualified personnel.
Hope this helps some.
Anyone working on Service Entrance equipment is well advised to follow ALL of the recommendations of NFPA-70E, the Standard on Electrical Safety. See: https://catalog.nfpa.org/NFPA-70E-Standard-for-Electrical-Safety-in-the-Workplace-P1197.aspx
Moreover, if someone asks you to work on, or look at, an Electric Motor Driven Fire Pump Controller -- DON'T. Unless you are also familiar with NFPA-20 and NFPA-25 on Fire Pumps and Testing, Inspection and Maintenance of same.
Note that almost all modern Electric Drive Fire Pump Controllers are labeled and tested as being suitable for connection to utility sources capable of 100,000 Amps Short Circuit Current. While older controllers may be labeled with lower ratings, such as 30 or 50 Kampers, they are often connected to sources which have been upgraded to the 100 Kamp category.
This equipment is VERY dangerous. I have witness testing fire pump controllers in 100 Kamp and 200 Kamp test labs. The explosion shown the the above video is, if anything, understated for higher fault current utility sources. I've seen test where the door of a controller is blown open by the internal explosion and parts are ejected.
Further, note that a controller subjected to a short current above it's rated capabality is no longer save to operate or to be near since this is stand-by equipemnt which can operate at any time. The fire pump motors involved typically range form 30 Hp to 400 Hp, with the average being around 100 Hp. Motor short circuits can and DO occur, either in the motor junction box, or in the motor internal windings. Hence they become a potential source of arc flash when the controller attempts to start said motor.
This is why both NFPA-70 and NFPA-20 stress that these equipments should be worked on ONLY by suitably qualified personnel.
Hope this helps some.
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