Tom Horne wrote:
>> Are there actually installations that can withstand three
>> inches of radial ice? Once the ice passes 0.3 inches here
>> we're heading for a major power and communications failure
>> with ordinary residential streets looking like plates of
>> spaghetti.
>
> I plead guilty of hyperbole. Even in northern states ("heavy
> loading" district), the specified maximum ice loading is 0.5
> inches of ice with a wind pressure of 4 psf.
>
> My point, however, stands: in a crosswind, communications
> cables can put large lateral forces on utility poles. With
> or without radial ice, these forces can equal, or even exceed,
> the forces caused by the action of the wind on electric power
> conductors.
>
> Of course, a lot depends on the relative size and quantity
> of electrical conductors vis-à-vis the communications cables
> and the relative wind speeds at different elevations above
> ground.
>
> In any case, the lateral forces caused by communications
> cables produce lower bending moment at the base of the pole
> simply because they're closer to the base of the pole.
>
> I should add that these observations are based on field
> experience, not empirical research. There's virtually no
> published research on the subject.
>
> Neal McLain
Much of the heavy loading area is not confined to the northern states. The central part of the country is more subject to ice storms and freezing rain which adheres to cables and wires. The dividing line brtween heavy loading and less severe runs east and west across Oklahoma, for example.
Wes Leatherock snipped-for-privacy@yahoo.com snipped-for-privacy@aol.com =0A=0A=0A