Attachment J.10 DC BUS Grounding Requirements.pdf

SIR 693KA8-20-R-00008

ATTACHMENT J.10, DC BUS Grounding Requirements

09/24/19

REMOTE AIR TO GROUND COMMUNICATION FACILITIES (RCAG, RTR,

AND BUEC)

The DC Bus System ground bar must be connected to the Main Ground Plate via a 1/0 AWG solid green cable with brass tags on each end. The tags must identify the far end termination, and be embossed with “Do Not Disconnect lead". This connection (Reference Ground / Grounding Electrode Conductor) must be a dedicated run.

Note: The Main Ground Plate should be connected to the counterpoise via a 500 (or 2-

250) kcmil cable. This connection is the FAA’s responsibility.

The DC Bus System equipment rack (chassis) must be connected to the Multipoint Ground via a 2 AWG green/orange cable. A secondary path to ground for the equipment rack must be accomplished via an existing grounded cable tray, or a DC BUS-installed 4 x 4 square duct raceway (DC Wireway) installed above the DC Bus System equipment rack that runs between the equipment rack and the radio cabinets. The raceway sections must be bonded together following FAA-STD-019F para. 4.7.4.2. If raceway does not follow FAA-STD-019F para. 4.7.4.2, then the individual sections or metallic cable tray and wireway systems must be bonded with a minimum 6 AWG insulated copper conductor. One raceway end must be connected to the radio cabinets (via metal to metal, or via external bonding conductor on the flex conduit); both raceway ends must be connected to Multipoint Ground via a 6 2 AWG green/orange cable.

Note: The Multipoint Ground Plate should be connected to the Main Ground Plate via an existing 4/0 cable. This connection is the FAA’s responsibility.

The DC Bus System battery frame must be connected to the Multipoint Ground via a 2 AWG green/orange cable.

Note: For proper performance of the DC Bus System, the negative return for the batteries is connected to the DC Bus System ground bar via the Anderson quick disconnect and the 4/0 AWG cable.

The ERMS P1 and P7B Panels must be connected to the Multipoint Ground via a 6 AWG green/orange cable (as long as they are within 13 ft. of a multipoint plate, if not see FAA- STD-019F table 3). A secondary ground path from the ERMS panels to multipoint ground is not required, as other (fortuitous) grounds exist. Ex: the AC power cables are installed in grounded ¾” EMT, there are shielded cables in the panels, etc.

Note: If only one ground (Main Ground Plate or Multipoint Ground) is available at the facility, all connections must be made to this ground. This ground should be connected by the FAA to the counterpoise via a 500 (or 2-250) kcmil cable.

SIR 693KA8-20-R-00008

ATTACHMENT J.10, DC BUS Grounding Requirements

09/24/19

SMALL AIR TRAFFIC CONTROL TOWERS (ATCT)

The DC Bus System ground bar must be connected to Building Steel or the Main Ground Plate via a 1/0 AWG solid green cable with brass tags on each end. The tags must identify the far end termination, and be embossed with “Do Not Disconnect lead". This connection (Reference Ground / Equipment Grounding Conductor) must be a dedicated run.

Note: From building steel an existing cable should be connected to Multipoint Ground.

The Multipoint Ground should be connected to the Main Ground Plate via a 4/0 AWG cable. The Main Ground Plate should be connected to the counterpoise via a 500 kcmil cable. These connections are the FAA’s responsibility.

The DC Bus System equipment rack (chassis) must be connected to the Multipoint Ground via a 2 AWG green/orange cable. A secondary path to ground for the equipment rack must be accomplished via an existing grounded cable tray or conduit, or a DC BUS-installed 4 x 4 square duct raceway (DC Wireway) installed above the DC Bus System equipment rack that runs between the equipment rack and the radio cabinets. The raceway sections must be bonded together following FAA-STD-019F para. 4.7.4.2. If raceway does not follow FAA-STD-019F para. 4.7.4.2, then the individual sections or metallic cable tray and wireway systems must be bonded with a minimum 6 AWG insulated copper conductor. One raceway end must be connected to the radio cabinets (via metal to metal, or via external bonding conductor on the flex conduit); both raceway ends must be connected to Multipoint Ground via a 6 2 AWG green/orange cable.

The DC Bus System battery frame must be connected to the Multipoint Ground via a 2 AWG green/orange cable.

Note: For proper performance of the DC Bus System, the negative return for the batteries is connected to the DC Bus System ground bar via the Anderson quick disconnect and the 4/0 AWG cable, or larger (to minimize voltage drop),if necessary.

When the batteries are located more than 25 feet from the DC Bus System, an over-current protection device must be installed at the battery; a 200 Amp circuit breaker is preferred.

The Environmental Remote Monitoring System (ERMS) P1 and P7B Panels must be connected to the Multipoint Ground via a 6 AWG green/orange cable (as long as they are within 13 ft. of a multipoint plate, if not see FAA-STD-019F table 3). A secondary ground path from the ERMS panels to multipoint ground is not required, as other (fortuitous) ground paths exist. Ex: the AC power cables are installed in grounded ¾” EMT, there are shielded cables in the panels, etc.