WEBVTT NOTE Tower Climbing and Grounding 1 00:00:00.000 --> 00:00:08.600 Climbing. Three questions, one practice, and it is the practice that matters more than the answers. 2 00:00:08.600 --> 00:00:15.440 Question. What is meant by "100% tie-off" regarding tower safety? 3 00:00:16.340 --> 00:00:22.700 Answer. At least one lanyard attached to the tower at all times. 4 00:00:23.300 --> 00:00:26.248 At all times, including while moving. 5 00:00:26.248 --> 00:00:41.464 A fall-arrest harness with two lanyards makes this possible: you attach the second before releasing the first, so you are never unattached even for the moment it takes to pass an obstruction. 6 00:00:41.464 --> 00:00:46.314 Question. To what should lanyards be attached while climbing? 7 00:00:47.214 --> 00:00:49.909 Answer. Tower legs. 8 00:00:50.509 --> 00:01:07.229 The legs are the structural members. Rungs are for standing on, guy brackets are attachment hardware for something else, and a mast is not part of the tower's structure. None of them is rated to arrest a fall. 9 00:01:07.229 --> 00:01:14.396 Question. Where should a shock-absorbing lanyard be attached to a tower when working above ground? 10 00:01:15.296 --> 00:01:19.136 Answer. Above the climber's head level. 11 00:01:19.736 --> 00:01:26.887 Above head level, which minimises the distance you fall before the lanyard takes the load. 12 00:01:26.887 --> 00:01:42.619 Attach at waist height and you fall twice the lanyard's length before it catches, and the peak force rises with the drop, which is what the shock absorber is there to manage. Give it less to absorb. 13 00:01:42.619 --> 00:01:48.976 The three together: always attached, to a tower leg, above your head. Grounding. 14 00:01:48.976 --> 00:01:57.070 Question. What is the primary function of an external earth connection or ground rod? 15 00:01:57.970 --> 00:02:01.687 Answer. Lightning charge dissipation. 16 00:02:02.287 --> 00:02:15.860 Note what it is not for. It is not the safety ground in your mains wiring, which comes back through the service panel. It is not an RF ground for antenna performance. 17 00:02:15.860 --> 00:02:26.245 Its primary job is giving a lightning charge a low-impedance path into the earth before it goes through your equipment, or you. 18 00:02:26.245 --> 00:02:43.579 The distinction matters because the three grounds are often confused and served by different conductors: Ground, Lightning; Purpose, dissipate a strike into earth; Path, short, straight, heavy conductor to a rod. 19 00:02:43.579 --> 00:02:59.851 Ground, Mains safety; Purpose, trip a breaker on a fault; Path, back through the service panel. Ground, RF; Purpose, provide a counterpoise or reference; Path, radials, or the station bonding system. 20 00:02:59.851 --> 00:03:16.858 All station ground rods must be bonded together and to the mains service ground, separate, unbonded rods can sit at very different potentials during a strike, and the difference appears across your equipment. 21 00:03:16.858 --> 00:03:29.859 Check yourself. You need to pass a guy bracket while climbing. How do you stay 100% tied off? Why attach the lanyard above your head rather than at your waist? 22 00:03:29.859 --> 00:03:37.218 You drive a new ground rod for the tower, well away from the house. What must you do next? 23 00:03:43.218 --> 00:03:52.760 Attach the second lanyard above the obstruction first, then release the first. Two lanyards are what make continuous attachment possible. 24 00:03:52.760 --> 00:04:06.272 It minimises the fall distance before the lanyard loads, and therefore the peak force the shock absorber must dissipate. Bond it to the other station ground rods and to the mains service ground. 25 00:04:06.272 --> 00:04:14.142 Unbonded rods can differ greatly in potential during a strike, and that difference appears across your equipment.