213 LIGHTNING CONDUCTORS. 



ridge of roof and connected to eight points from which similar 

 strip is taken down to eight earth connections. As the brief 

 suggestions which follow may serve to indicate, seven of these 

 "earths" are quite unnecessary and, further, had an equivalent 

 weight of copper been used in the form of a light stranded 

 wire, very much better protection would be afforded. 



6. The determination of the size and section of the conduc- 

 tor, whether of copper or iron, depends more upon mechanical 

 strength and durability than conductive properties. There is 

 little danger of the wires becoming melted and, if the system is 

 inter-connected, the fusion of certain lengths would not affect 

 the utility of the conductor as a whole to any serious extent. 

 The network advocated by the writer would deal with succeed- 

 ing discharges whereas a break in a single conductor has fre- 

 quently been the cause of damage. Fusion of part of the net- 

 work would not escape notice and, in a sense, would be satis- 

 fatory in affording proof that the conductor had seen active 

 service. 



7. The material used by the writer is galvanised iron in the 

 form of a light cable composed of seven strands of number 

 sixteen gauge wire. (7/18) This affords ample mechanical 

 strength, is pliable and unobtrusive in appearance. Zinc saddles 

 are used to secure it to ridges of roof and down walls to earth. 

 It is frequently possible to make use of the down pipes from 

 roof gutters by running the conductor through them. 



8. In order to make the system as far as possible jointless as 

 regards the work on the roof, which usually escapes supervision, 

 the writer has recently designed a tubular point through which 

 the conductor itself is drawn, doubled, and allowed to project an 

 inch or so from the top. A set-screw at the base provides suf- 

 ficient contact without the necessity of soldering — often so 

 awkward an .operation on a roof that it is left undone al- 

 together. The point is practically formed of the conductor it- 

 self and joints become unnecessary above ground. 



9. The number of points and the amount of wire used for 

 any building must depend upon the degree of safety desired 

 and the funds available for providing it. The fact that many 

 points and much wire mean better protection should be tho- 

 roughly recognised. In practice something must be sacrificed to 



Jour Straits Branch 



