Code of Massachusetts Regulations › 220 CMR - DEPARTMENT OF PUBLIC UTILITIES › Title 220 CMR 125.00 - Installation And Maintenance Of Electric Transmission Lines › Section 125.24 - Loadings

Current through Register 1525, July 5, 2024
(1)
Loading on
		Conductors
. The loading on conductors at 0° F shall be assumed
		to be:
We =
		  Wv2 +
		  Wh2 + K
where:
We = Resultant loading in pounds per
		  foot of conductor length.
W v = Vertical load in pounds per foot
		  of conductor length, covered with 1/2 inch radial thickness of ice.
Wh = Transverse loading in pounds per
		  foot of conductor length due to a transverse, horizontal wind pressure of four
		  pounds per square foot upon the projected area of the conductor, covered with
		  1/2 inch radial thickness of ice.
K = 0.29 for bare conductor of copper, steel, copper alloy,
		  copper-covered steel, aluminum-covered steel, and combinations thereof
K = 0.31 for bare conductors of aluminum (with or without steel
		  reinforcement).
In applying loadings to bare stranded conductors, the coating
		  office shall be considered as a hollow cylinder touching the outer
		  strands.
Ice is assumed to weigh 57 pounds per cubic foot. The weight of
		  ice in pounds per lineal foot can be calculated by the formula:
Weight of Ice = 1.243 t (D+t) where:
D = Diameter of conductor in inches
t = Radial thickness of ice in inches
(2)
Loadings on Line
		Supports.
(a)
General
. The loads upon line supports shall be the
		loads delivered by the conductors, including conductor tensions, when loaded as
		specified in 220 CMR 125.24(1), assuming all conductors intact, plus the weight
		of the supports plus the wind load on supports. In combining loads, due account
		shall be taken of different directions of loads.
(b)
Weight of and Wind on
		Conductors
. The vertical load delivered to the support by the
		conductor shall be calculated using the weight span S v,
		which is the horizontal distance between the low points of sag in the two spans
		adjacent to the support concerned,
i.e.
,
		Wv x Sv .
The wind load delivered to the support by the conductor shall
		  be calculated using the wind span S h , which is the
		  average of the two spans adjacent to the support concerned,
i.e.,
Wh x Sh
		  .
(c)
Weight of Ice on Supports
. The weight of ice upon
		supports may be ignored for the sake of simplicity.
(d)
Wind Loading on
		Supports
. The minimum wind loading shall be assumed as four pounds
		per square foot on projected area of cylindrical surfaces, and 6.4 pounds per
		square foot on flat surfaces.
For latticed bodies of structures, the actual exposed area of
		  one face shall be increased by 50% to allow for the pressure on the opposite
		  face. This total, however, need not exceed the pressure which would occur on a
		  solid structure of the same outside dimensions. The results obtained by more
		  exact calculations may be substituted for the values obtained in 220 CMR
		  125.24.
(e)
Wind Direction
. Wind direction shall be assumed which
		will give the maximum stresses in all parts of the structure, proper reduction
		being made to account for the reduced wind pressure on the wires resulting from
		the angularity of the application of the wind to the wires.
(f)
Simultaneous Application of
		Loads
. All applicable loads shall be taken as acting
		simultaneously.