General Order 64-A
Section XI
Supply Lines And Communication Lines Crossings Over Railways
113.4
Short Spans.
In cases where the crossing span
is constructed of such height that its length is less than the distance between
either point of support of its lowest conductor and the highest conductor of
the line crossed (or top of rail if no line is crossed) the requirements for
conductor sag and for size and type of the conductors required are waived,
provided that a permanently grounded guard arm is installed at each crossing
support in such a manner as to prevent the conductors which may break from
swinging back into the conductors of span (or the rail) crossed over.