Ground Fault Protecton - Airport Airfield System

[smullen]

I have a design application with 480/277V double-ended (main-tie-main), 2000A cont. switchgear and with a backup emergency generator. Currently, I have included GFP on all circuit breakers - mains, tie, and feeder breakers for the 480/277V Switchgear. Switching is completed through the switchgear circuit breakers rather than a ATS. The switchgear has redundant generator circuit breakers. Which means the switchgear has (2) circuit breakers, one on each side of the split bus leading to the emergency generator. My question is concerning ground fault protection. If the scenairo came up that both utility service feeders leading to 480/277V switchgear had failed (lost power) and generator was the only prime mover, should GFP be enabled on the circuit breakers? My thought is that GFP could pickup and nuissance trip if not set properly. This systems feeds airport lighting on the airfield and is a critical system because people's lives are on the line. The NEC does not state much on airport systems. I have been looking at Health Care Facilities NEC guidelines figuring this may be a good start and a conservative approach. NEC 517-17, prohibits the installation of GFP between on-site generator(s) and any EES transfer switch feeding EES switch feeding EES Circuits. This tells me that there should not be GFP. Is there another place that would cover my application? Is this the right way (Health Care Facilites) to look at this application?

 

[bennie]

Re: Ground Fault Protecton - Airport Airfield System

Consult the manufacturer of the lighting equipment.

This installation will likely come under government specs, with the FAA.

 

[charlie]

Re: Ground Fault Protecton - Airport Airfield System

Also, keep in mind that this is probably outside of the normal AHJ's territory. The AHJ may be a design engineer or a US Government inspector.

 

[smullen]

Re: Ground Fault Protecton - Airport Airfield System

Thanks, Bennie, but FAA Circulars discuss standby systems, but not GFP.

Originally posted by bennie:
Consult the manufacturer of the lighting equipment.

This installation will likely come under government specs, with the FAA.

[ May 13, 2003, 09:58 AM: Message edited by: smullen ]

 

[bennie]

Re: Ground Fault Protecton - Airport Airfield System

This is a calculated guess, from one who has been involved in two emergency landings in military aircraft.

The primary intent is to maintain power for the runway lights. When the utility power shuts off, the generator will go on line. Any problem developing will not affect the utility system.

GFP devices will defeat the continuity of service requirement. Better to burn clear than to dump.
This situation takes on the same approach as a fire pump, for continued operation.

I would not install GFP unless directed by the authority having jurisdiction.