for sagging conductors. Factors that must be considered when sagging conductors are creep elongation
during stringing and prestressing of the conductor.
Creep elongation during stringing: Upon completion of conductor stringing, a time of up to several
days may elapse before the conductor is tensioned to design sag. Since the conductor tension during the
stringing process is normally well below the initial sagging tension, and because the conductor remains
in the stringing sheaves for only a few days or less, any elongation due to creep is neglected. The
(^400020)
25
30
35
40
45
50
60
70
80
2.5^90
150
200
250
300
350
400
500
B
C
A
Formulas for Equivalent Span Length
Equiv. Deadend Span = 2C - A
Equiv. Suspension Span = A C
SAG
S
3500
3000
2500
2000
1500
1000
2
3
4
5
10
15
20 5
7.5
10
12.5
15
20
25
37.5
20
62.5
75
25
30
40
50
60
80
100
150
200
250
300
For spans between a suspension and deadend
tower, use suspension span correction.
Example: Assume span with A = 1000 ft,
B = 100 ft if deadend span, correction = 10 ft
(see above). If suspension span, correction =
2.5 ft (see above). Equivalent span = 1000 ft +
correction. Read chart sag for equivalent span
length.
Sag is based on parabolic functions.
If sag exceeds 5% of span, do not use this chart.
Sag is based on parabolic functions.
If sag exceeds 5% of span, do not
use this chart.
Deadend
Span
Suspension
Span
Horizontal Spacing of Supports (A)
900
800
700
600
500
400
300
200
100
∗
∗
Equivalent Span Correction
(Add to Horiz. Spacing to Obtain Equivalent Span Length)
Vertical Spacing of Supports (B)
100
FIGURE 14.14 Nomograph for determining level span equivalents of non-level spans.