LIGHTNING RODS 



439 



Installation of a lightning-rod system. One of the most 

 important features in a lightning-rod system is to have the 

 lower end of the conductor placed so deep in the ground 

 that it is always in moist earth. The upper end should be 

 a point and should extend approximately 30 inches above 

 the highest point of the building. Points should be well 

 plated or galvanized so that they will not rust and become 

 blunt. The cupola of the barn, the chimney of the house, 



Fig. 333. Showing position of the 

 ground wires on a building. When the 

 line B-E does not exceed 30 feet, ground 

 wires at A and F are sufficient. When 

 B-E is greater than 30 feet, grounding at 

 either D or C should be installed at a 

 point halfway between B and E. When 

 B-E is greater than 60 feet, the ground 

 wires A, C, D, and F should be installed 

 as shown in the figure. B-E represents the 

 length of the ridge of the building. A and 

 F are opposite diagonal corners. An L- 

 shape building should have three ground 

 wires and a square building either two or 

 four. 



?r 



ft 



and the top of the silo should be protected by points. The 

 conductors should be fastened directly to the building with 

 either metal staples or wooden cleats and should have a 

 metallic connection with the eave spouts, door hangers, 

 metal ventilators, hay carriers, and all other metal parts 

 of the building. For small buildings two conductors passing 

 into the ground at diagonal corners of the building are suffi- 

 cient. Larger buildings should have three, and the largest 

 of farm buildings should have four. The third and fourth 

 ground conductors should be so placed that they will collect 

 and carry their proper proportion of the current. Ground 

 conductors should enter the ground under the downspout, 

 or, if there are no downspouts, under the eave-drip, the 

 object being to get them into the ground where there will 



