ERICO ISODC Isolated Downconductor System - Manual (Page 5)

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Table 1. Height versus horizontal distance using protection angle method.
Height h of air-
termination (m)
Distance d (m) and protection angle ␣Њ (rounded down to nearest degree)
LPL I LPL II LPL III LPL IV
Distance Angle Distance Angle Distance Angle Distance Angle
1 2.75 70 3.27 73 4.01 76 4.70 78
2 5.49 70 6.54 73 8.02 76 9.41 78
3 7.07 67 8.71 71 10.46 74 12.99 77
4 7.52 62 9.42 67 12.31 72 13.95 74
5 8.32 59 10.25 64 14.52 71 16.35 73
6 8.57 55 10.82 61 14.14 67 17.43 71
7 9.29 53 11.65 59 15.72 66 18.24 69
8 9.53 50 12.32 57 16.40 64 18.85 67
9 9.65 47 12.85 55 16.93 62 20.21 66
10 10.00 45 13.27 53 17.32 60 20.50 64
11 9.90 42 14.08 52 19.05 60 19.84 61
12 10.07 40 14.30 50 19.20 58 20.78 60
13 10.16 38 14.44 48 19.27 56 21.64 59
14 9.80 35 14.50 46 19.27 54 22.40 58
15 9.74 33 15.00 45 19.91 53 23.10 57
16 9.61 31 14.92 43 20.48 52 22.85 55
17 9.04 28 15.31 42 20.99 51 23.40 54
18 8.78 26 15.65 41 21.45 50 23.89 53
19 8.86 25 15.94 40 21.86 49 25.21 53
20 7.68 21 15.07 37 21.45 47 25.60 52
21 14.70 35 21.75 46 25.93 51
22 14.84 34 22.00 45 26.22 50
23 14.94 33 22.21 44 27.41 50
24 14.42 31 22.38 43 26.65 48
25 14.43 30 22.51 42 26.81 47
26 13.82 28 21.82 40 27.88 47
27 13.17 26 22.66 40 27.96 46
28 13.06 25 21.88 38 28.00 45
29 12.91 24 21.85 37 28.00 44
30 12.73 23 21.80 36 28.97 44
31 21.71 35 28.91 43
32 21.58 34 28.81 42
33 21.43 33 28.69 41
34 21.25 32 28.53 40
35 21.03 31 28.34 39
36 20.78 30 29.15 39
37 20.51 29 28.91 38
38 20.20 28 28.64 37
39 19.87 27 29.39 37
40 19.51 26 29.06 36
1. DESIGN
(continued)