POLE-LINE CONSTRUCTIONPOLE-LINE CONSTRUCTION60. A single crossarm assembly for a two-wire single-phase circuit is shown in Fig. 8.47. Additional insulators for three- or four-wire lines can be added to the arm 14½ in. (368.3 mm) closer to the pole from the insulators shown. This type of arm is used for normal spans and loads when there is a straight line with no obstructions.
Terrell Croft; Frederic P. Hartwell; Wilford I. Summers: American Electricians' Handbook, Sixteenth Edition. POLE-LINE CONSTRUCTION, Chapter (McGraw-Hill Professional, 2013), AccessEngineering