FARM MANAGEMENT 133 



Whether or not to install lightning conductors on one's property 

 is a question, after all, of individual judgment. If the property is 

 insured against loss by lightning there would be little incentive 

 toward incurring additional expense for lightning conductors. In case 

 of an isolated farm building standing apart from trees it would seem 

 that the conservative course would be to erect an inexpensive system 

 of lightning conductors. 



An inexpensive yet effective lightning conductor can be erected 

 by any one out of materials that can be purchased from the larger 

 electric supply houses. No. 3 and No. 4 double galvanized iron tele- 

 graph wires make an excellent lightning conductor. While iron is 

 not so good a conductor as copper, it is less likely to cause dangerous 

 side flashes and it also dissipates the energy of the lightning flash 

 more effectively than does the copper. 



The conducting system is composed of a horizontal wire follow- 

 ing the ridge of the roof and two vertical wires connecting with the 

 ground on both sides of the building. The wires should be fastened 

 to the building by galvanized iron staples about an inch long; they 

 are not to be insulated from it as was once the practice. Another way 

 to fasten the wire to the building is by means of small wooden blocks 

 and screw eyes. Blocks l 1 /^ inches thick, 2 1 / inches wide, and 4 

 inches long into which a stout screw eye is fastened may be nailed to 

 the sides and the roof at intervals of 10 feet or less. The wire can be 

 easily passed through these eyes from the ground to the top of the 

 building. 



The vertical wires should be connected to the horizontal wire by 

 galvanized iron T's. The necessary T's should be slipped onto the 

 horizontal wire and placed at points of junction with the downward 

 directed wires, and also at such points as it is wished to erect short 

 terminal rods along the ridge of the roof. 



The end terminals are best formed by making a right angle bend 

 in the wire which runs along the ridge of the roof at a distance of 20 

 inches from the respective ends. The middle terminal is merely a 

 wire 20 inches in length held in place by a T connector. The ter- 

 minals are short and offer little resistance to the wind ; they are kept 

 in a vertical position by the connections between the ridge wire and 

 the wires leading to the ground. 



The end of the upper terminal should not be left blunt, but 

 should be filed down until it is cone shaped. Since the filing removes 

 the galvanizing over the surface of the cone, the latter should be 

 heavily coated with paint to preserve it from rust. In general a ter- 

 minal rod should be erected every 18 or 20 feet along the ridge of the 

 roof. 



The number of terminal wires depends on the number of cupo- 

 las, chimneys, or other salient points on the roof liable to be struck. 

 A short terminal wire connected to the main conducting wire by a T 

 should be erected at each cupola or other salient point. 



The earth connections require great care in their construction. 

 The essential thing is to reach permanently moist earth in the short- 

 est distance from the main conductors. Some buildings have two 



