ERICO ISODC Isolated Downconductor System - Manual (Page 6)

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Table 1. Height versus horizontal distance using protection angle method. (continued)
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
41 19.12 25 29.79 36
42 18.70 24 30.51 36
43 18.25 23 30.11 35
44 18.68 23 28.57 33
45 18.18 22 29.22 33
46 28.74 32
47 28.24 31
48 27.71 30
49 28.29 30
50 28.87 30
51 28.27 29
52 28.82 29
53 29.38 29
54 28.71 28
55 28.02 27
56 27.31 26
57 26.58 25
58 25.82 24
59 25.04 23
60 25.47 23
h
1
d
1
d
2
h
2
␣
1
Protected
Not Protected
Table 2. Lightning Protection Levels
Lightning Protection Level
(Class of LPS)
Peak current (10/350 µs) Probability of exceedance
I 200 kA ≤ 1 %
II 150 kA ≤ 3 %
III 100 kA ≤ 9 %
IV 100 kA ≤ 16 %
1. DESIGN
(continued)
␣
2