| 174 / | HD | ELECTRICITY: CONDUCTORS AND INSULATORS | 
| 137 R | DF | INSULATORS {17} | 
| 158 R | DF | .~ With insulator-supporting or attaching means {7} | 
| 164 | DF | .~.~ Support penetrating {2} | 
| 166 R | DF | .~.~.~ Through aperture, penetrating element clamped {1} | 
| 166 S | ![]()  | .~.~.~.~ Stand-off insulators |