Trolley wires, trolley feeder wires, and bare signal wires shall be adequately guarded:

(a) At all points where men are required to work or pass regularly under the wires; and

(b) At man-trip stations.

The Secretary or his authorized representative shall specify other conditions where trolley wires and trolley feeder wires shall be adequately protected to prevent contact by any person, or shall require the use of improved methods to prevent such contact. Temporary guards shall be provided where trackmen and other persons are required to work in proximity to trolley wires and trolley feeder wires.