Electric Power Generation, Transmission, and Distribution

TABLE 14.8 Time-Sag Table for Stopwatch Method

Return of Wave

Sag,
in.

3rd Time,

sec

5th Time,

sec

Sag,

in.

3rd Time,

sec

5th Time,

sec

Sag,

in.

3rd Time,

sec

5th Time,

sec

Sag,

in.

3rd Time,

sec

5th Time,
sec
5 1.9 3.2 55 6.4 10.7 105 8.8 14.7 155 10.7 17.9
6 2.1 3.5 56 6.5 10.8 106 8.9 14.8 156 10.8 18.0
7 2.3 3.8 57 6.5 10.9 107 8.9 14.9 157 10.8 18.0
8 2.4 4.1 58 6.6 11.1 109 9.0 15.0 158 10.9 18.1
9 2.6 4.3 59 6.6 11.1 109 9.0 15.0 159 10.9 18.1
10 2.7 4.6 60 6.7 11.1 110 9.1 15.1 160 10.9 18.2
11 2.9 4.8 61 6.7 11.2 111 9.1 15.2 161 11.0 18.2
12 3.0 5.0 62 6.8 11.3 112 9.1 15.2 162 11.0 18.2
13 3.1 5.2 63 6.9 11.4 113 9.2 15.3 163 11.0 18.4
14 3.2 5.4 64 6.9 11.5 114 9.2 15.4 164 11.1 18.4
15 3.3 5.6 65 7.0 11.6 115 9.3 15.4 165 11.1 18.5
16 3.5 5.8 66 7.0 11.7 116 9.3 15.5 166 11.1 18.5
17 3.6 5.9 67 7.1 11.8 117 9.3 15.6 167 11.2 18.6
18 3.7 6.1 68 7.1 11.9 118 9.4 15.6 168 11.2 18.7
19 3.8 6.3 69 7.2 12.0 119 9.4 15.7 169 11.2 18.7
20 3.9 6.4 70 7.2 12.0 120 9.5 15.8 170 11.3 18.8
21 4.0 6.6 71 7.3 12.1 121 9.5 15.8 171 11.3 18.8
22 4.0 6.7 72 7.3 12.2 122 9.5 15.9 172 11.3 18.9
23 4.1 6.9 73 7.4 12.3 123 9.6 16.0 173 11.4 18.9
24 4.2 7.0 74 7.4 12.4 124 9.6 16.0 174 11.4 19.0
25 4.3 7.2 75 7.5 12.5 125 9.7 16.1 175 11.4 19.0
26 4.4 7.3 76 7.5 12.5 126 9.7 16.2 176 11.4 19.1
27 4.5 7.5 77 7.6 12.6 127 9.7 16.2 177 11.5 19.1
28 4.6 7.6 78 7.6 12.7 128 9.8 16.3 178 11.5 19.2
29 4.6 7.7 79 7.7 12.8 129 9.8 16.3 179 11.5 19.3
30 4.7 7.9 80 7.7 12.9 130 9.8 16.4 180 11.6 19.3
31 4.8 8.0 81 7.8 13.0 131 9.9 16.5 181 11.6 19.4
32 4.9 8.1 82 7.8 13.0 132 9.9 16.5 182 11.6 19.4
33 5.0 8.3 83 7.9 13.1 133 10.0 16.6 183 11.7 19.5
34 5.0 8.4 84 7.9 13.2 134 10.0 16.7 184 11.7 19.5
35 5.1 8.5 85 8.0 13.3 135 10.0 16.7 185 11.7 19.6
36 5.2 8.6 86 8.0 13.3 136 10.1 16.8 186 11.8 19.6
37 5.3 8.8 87 8.1 13.4 137 10.1 16.8 187 11.8 19.7
38 5.3 8.9 88 8.1 13.5 138 10.1 16.9 188 11.8 19.7
39 5.4 9.0 89 8.1 13.6 139 10.2 17.0 189 11.9 19.8
40 5.5 9.1 90 8.2 13.7 140 10.2 17.0 190 11.9 19.8
41 5.5 9.2 91 8.2 13.7 141 10.3 17.1 191 11.9 19.9
42 5.6 9.3 92 8.3 13.8 142 10.3 17.1 192 12.0 19.9
43 5.7 9.4 93 8.3 13.9 143 10.3 17.2 193 12.0 20.0
44 5.7 9.5 94 8.4 14.0 144 10.4 17.3 194 12.0 20.0
45 5.8 9.7 95 8.4 14.0 145 10.4 17.3 195 12.1 20.1
46 5.9 9.8 96 8.5 14.1 146 10.4 17.4 196 12.1 20.1
47 5.9 9.9 97 8.5 14.2 147 10.5 17.4 197 12.1 20.2
48 6.0 10.0 98 8.5 14.2 148 10.5 17.5 198 12.1 20.0
49 6.0 10.1 99 8.6 14.3 149 10.5 17.6 199 12.2 20.3
50 6.1 10.2 100 8.6 14.4 150 10.6 17.6 200 12.2 20.3
51 6.2 10.3 101 8.7 14.5 151 10.6 17.7 201 12.2 20.4
52 6.2 10.4 102 8.7 14.5 152 10.6 17.7 202 12.3 20.5
53 6.3 10.5 103 8.8 14.6 153 10.7 17.8 203 12.3 20.5
54 6.3 10.6 104 8.8 14.7 154 10.7 17.9 204 12.3 20.6

Note: To calculate the time of return of other waves, multiply the time in seconds for one wave return by the number of wave
returns or, more simply, select the combination of values from the table that represents the number of wave returns desired. For
example, the time of return of the 8th wave is the sum of the 3rd and 5th, while for the 10th wave it is twice the time of the 5th.
The approximate formula giving the relationship between sag and time is given as:
D¼ 12 : 075 T
N

 2

(inches)

where D¼sag, in.

T¼time, sec

N¼number of return waves counted