specifications - FAACO - Federal Aviation Administration Contract ...

FTWIC-2235June 2009In highly humid or corrosive atmospheres, adequate protection against corrosionshall be provided.9. CONDUIT: All metal conduit used for electronic signal and control wiring shallbe grounded as follows:All joints between conduit sections and between conduit, fittings, and boxes shallbe electrically continuous. All pipe and locknut threads shall be treated with aconductive lubricant prior to assembly. Joints that are not otherwise electricallycontinuous shall be bonded with short jumpers of No. 12 AWG or larger copperwire. The jumpers shall be welded or brazed in place or shall be attached withclamps, split bolts, grounding bushings, or other devices approved for thepurpose. All bonds shall be protected against corrosion. Cover plates of conduitfittings, pull boxes, junction boxes, and outlet boxes shall be grounded bysecurely tightening all available screws.Every component of metallic conduit runs such as individual sections, couplings,line fittings, pull boxes, junction boxes and outlet boxes shall be bonded, eitherdirectly or indirectly, to the electronic multipoint ground system or facility steelat intervals not exceeding 50 feet. Conduit brackets and hangers shall besecurely bonded to the conduit and to the metal structure to which they areattached.SIZE OF ELECTRONIC MULTIPOINT GROUND CABLESCable Size Max. Path Length Bus Bar Size Max. Path Length(feet) (inches) (feet)750 KCMIL 375 4 1/4 636600 KCMIL 300 4 1/8 318500 KCMIL 250 3 1/4 476350 KCMIL 175 3 1/8 238300 KCMIL 150 2 1/4 318250 KCMIL 125 2 1/8 1594/0 AWG 105 1 1/16 793/0 AWG 84 1 1/4 1592/0 AWG 66 1 1/8 791/0 AWG 53 1 1/16 39AWG 412 AWG 334 AWG 216 AWG 138 AWG 8J. Install an earth electrode system in accordance with the requirements described in thisspecification. Ground rods shall be interconnected by a buried, bare, No. 4/0 AWGstranded copper cable. The cable shall be buried 30 inches below grade. Connections tothe ground rods shall be made by exothermic welding. The interconnecting cable shallclose on itself forming a complete loop with the ends exothermically welded. Thestructural steel of buildings shall be connected to the earth electrode system atapproximately every other column at intervals averaging not over 60 feet with a bare No.16450-6