General Order 64
Section IX
Detail Construction Requirements For Signal Lines – Class “S” Circuits
92 Crossarms And Pins.
(a) Strength: Crossarms shall be of fir or other suitable timber, and shall not be less than the following dimensions:
1. Arms 6 ½ feet or less in length, 2 ¾ inches by 3 ¾ inches.
2. Arms over 6 ½ feet in length, 3 inches by 4 ½ inches.
Wooden pins shall be of locust, eucalyptus, or other suitable wood, and shall be at least 1 ¼ inches in diamter.
Iron pins shall be at least ½ inch in diamter.