MIL-STD-1310H(NAVY)
5.3.3.3 Shielded multi-conductor cables. The overall shield(s) of multi-conductor cables shall be peripherally grounded using EMI backshells assembled in accordance with MIL-STD-2003-5 or equivalent.
5.4 EMP protection. When EMP protection requirements are invoked, the EMP protection requirements shall take precedence over the EMI reduction requirements specified in 5.3. However, this does not obviate the responsibility of meeting the EMC requirements of MIL-STD-464. The requirements specified in 5.4.1 through
5.4.5 shall apply to metallic hull surface ships on which EMP protection has been specifically authorized. For composite ships or structures integrated in metallic hull ships a PPD (see 4.5) shall be developed to address the EMP requirements of bonding and grounding. The grounding effectiveness of the connector/backshell/cable
shield system shall not be less than 60 dB over a frequency range of 100 kHz to 100 MHz. PCI testing shall be
used to measure the grounding effectiveness of the connector/backshell/cable shield system installation.
5.4.1 Cables. Except as noted below, all cables routed in topside areas shall be electromagnetically shielded and grounded at deck and superstructure penetrations. The shield of coaxial cable or overall shielded cable and shielding conduit terminating at topside equipment shall be peripherally grounded using coaxial connectors, EMI backshells in accordance with SAE-AS85049 or equivalent, or conduit termination fittings. Additionally, the shield and conduit shall be grounded at the penetration of the hull, superstructure, deck bulkhead, or wireway trunk. Rigid conduit, or flexible metal conduit in accordance with MIL-PRF-24758, shall be installed over single cable runs. Multi-cable runs shall use rigid or flexible metal conduit or wireway trunk. Cables shall be run within the structure of the ship or within enclosed masts wherever possible to minimize the addition of shielding conduit or wireway trunks. Unshielded cables routed internal to the ship shall not be routed within 12 inches of weather doorways, hatchways, and windows unless the cables are routed within shielding conduit or wireway trunks. Cables that terminate at these openings, such as windshield wiper cables, window de-icing cables, and door alarm cables, shall be shielded and grounded as close as practicable to the end fitting. Cables shall not be routed within
10 feet of helicopter or aircraft hangar bay doors or well deck access doors unless they are shielded or routed in conduit or wireway trunk.
5.4.2 Cable shielding performance. The installing activity shall be responsible for ensuring the topside cables specified in ICDs or OEM guidance associated with government furnished equipment and contractor furnished equipment will not degrade the required level of EMP hardness of the ship. Where there is no specified level of shielding for a ship class, the shielding system shall be designed to protect against any known system
vulnerabilities against the EMP threat as specified in MIL-STD-464. Where individual system hardness to EMP
has not been designed, the following cable shielding guidelines shall be used:
a. Single shielded cables routed less than 18 inches in topside areas do not require additional shielding. However, the overall shield of these cables shall be grounded at the weather penetration points.
b. Cables with a solid overall shield, such as RG-333, do not require additional shielding. However, the overall shield shall be grounded at the weather penetration point.
c. Double shielded cables routed less than 8 feet in topside areas do not require additional shielding. However, the cable shield shall be grounded at the weather penetration point.
d. Additional shielding is required for coaxial and single shielded cables with an exposure greater than 18 inches and double shielded cables with an exposure greater than 8 feet. The additional shielding shall be rigid
or flexible metal conduit (MIL-PRF-24758) or metal wireway trunk over the entire length of the cable.
When an alternative to the above items is offered by the installing activity, they shall, through analysis, computer modeling, or scale model testing, verify the expected level of shielding provided by the cable system, and the items shall be approved by the Technical Warrant Authority (see 4.6). The overall shielding provided by the cabling, conduit, shield ground adaptors, wireway trunks, and equipment enclosures shall be equal to or better than the level required for an individual ship hull and superstructure as specified in the ship specification.
5.4.3 Wireway trunks. Wireway trunks shall be constructed to provide 60 dB shielding effectiveness. A
typical wireway trunk is shown in figure 2.
5.4.4 Waveguides, pipes, tubing, and exhaust stacks. Waveguides, pipes, tubing, and exhaust stacks grounded as specified in 5.3.2.1.3 are properly grounded for EMP requirements.
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