453 



ENGINEERING ON THE FARM 



insulators, which arc necessary to insure a minimum of loss 

 of current. 



Protection. The connections between the pole line and 

 the building, such as a dwelling house, may be made by means 

 of bare wire, such as is used for the line proper, but while 

 metallic circuits are used it is better to use insulated wire 



in a twisted pair. If 

 bare wire is used, it is 

 necessary to draw it 

 tight to reduce the 

 probability of the two 

 wires swinging together, 

 and the humming of 

 tight wires attached to 

 buildings is objection- 

 able. If paired insulated 

 wire is used, it may be 

 left fairly slack between 

 the nearest pole and the 

 house. For attaching 

 the wire to the house, 

 porcelain or glass insulators attached by means of large 

 wood screws are very satisfactory where the building is of 

 wood. On brick or stone buildings expansion or toggle 

 bolts set in drilled holes are used. 



Where the wires pass through the walls of the house, por- 

 celain tubes should be used, and directly inside a lightning 

 arrestor should be installed. From the point where the 

 wire from the pole is attached to the building to the point 

 where it passes through the wall, it should be carried on 

 porcelain or glass insulators. The principal reason for this 

 is that heavy lightning discharges sometimes heat the wires 

 to such an extent that they constitute a fire hazard if sup- 

 ported directly against the woodwork. 



A satisfactory form of lightning arrestor is one having 

 blocks of carbon held between flat springs, the carbon 



After Western Electric Co. 



F IG - 353- Protector used for lightning and 



where lighting and power lines cross 



telephone lines 



