34 Pa. Code § 39.422
Before climbing poles, ladders, scaffolds or other elevated structures, care shall be taken to assure that the pole, ladder, scaffold, tree, crossarm, messenger wire, cable car, or boatswain's chair, or other elevated support, is strong enough to safely sustain weight. Poles may be tested for decay near the ground line with a bar, screwdriver or other tool, and sounded for decay at the center by rapping with a heavy tool or block of wood. When poles or crossarms are apparently unsafe from decay or unequal strains of wire on them they should be properly braced or guyed, if necessary, before they are climbed.
34 Pa. Code § 39.422
This section cited in 34 Pa. Code § 39.421 (relating to general provisions); 34 Pa. Code § 39.441 (relating to general provisions); and 34 Pa. Code § 39.461 (relating to general requirements).