Capture the lightning strike to a known and safe attachment point. This is usually an air terminal which is a copper rod with a very fine point that is extended on the tower above all antennas. This air terminal is bonded to the tower structure so that a direct lightning strike is encouraged to hit the air terminal and transfer the energy directly to the tower rather than through the antennas or cables.
The energy is safely conveyed to ground through the tower itself. All coaxial cables are grounded to the tower at 75 foot intervals to insure that the tower and the cables are on the same voltage potential at all times. This also insures that any lightning energy that may get into the antenna and cable system will be grounded out to the low impedance tower grounding system.
Dissipate the energy into a low impedance grounding system. A typical MapleNet grounding system involves a ground ring placed around the perimeter of the tower and building foundations and bonded to all other metal structures within the compound. The ground ring typically is buried below the frost line and all connections are exothermically welded rather than mechanical clamp connectors.
The photo at right shows the grounding kits which are installed every 75' on all vertical and horizontal cable runs. The kits attach to the copper jacket of the cable (shown in the green box) and then a copper jumper is mechanically attached to a grounding buss bar (shown in the yellow box). The buss bar, in turn, is connected to the main ground field using one or two leads of #2 copper wire, or wire strap.
In addition to grounding the cable every 75’ vertically along the tower it is grounded at the base of the tower and at the building entrance.
The photo at right shows the in-line lighting arrestors inside the building mounted to a copper buss bar.
The Solid # 2 tinned copper wire in the photo is exothermically welded to the ground rod to create a continuous ground ring around the tower.
Exothermically welded #2 solid tinned copper wire to tower leg. This wire connects each leg to the ground ring.
The photo shows the remnants of the trench where the tower ground ring was installed. The green lines show the ground ring which has ground rods spaced every 16’ around the perimeter of the foundation. Each tower leg is bonded to the ground ring as well as the power feeder lines coming into the tower and all coaxial cables running up the tower. All connections to the tower structure as well as sub-surface connections are exothermically welded. possible are exothermically welded. Other connections are compression lugged and bolted tight.
Trenching the grounding ring.
All data lines must be protected either using Ethernet surge protectors or in mission critical applications by using fiber optic transceivers and a jumper separating the radio equipment from the LAN.
4561 Pine Creek Rd.
Elkhart, IN 46516
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