Killingworth William Hedges

“ Insulators on the conductor are of no advantage, and it is useless to gild or otherwise protect the points of the air-terminals. As heated air offers a good path for lightning (which is the reason why the kitchen-chimney is often selected by the discharge) , a number of points should be fixed to high chimneys and there should be at least two conductors to earth. All roof metals, such as finials, flashings, rain-water gutters, ventilating pipes, cowls and stove pipes, should be connected to the system of conductors. ”

“ A copper rod allows the discharge to pass too quickly and produces a violent shock, whereas iron offers more impedance and allows the flash to leak away by damping down the oscillations. Thus there is less chance of a side flash from an iron than from a copper conductor.
Causes of Failure.—A number of failures of conductors were noticed in the 1905 report of the Lightning Research Committee. One cause was the insufficient number of conductors and earth connexions; another was the absence of any system for connecting the metallic portion of the buildings to the conductors. ”

“ A B flash may ignore the points and strike some metal work in the vicinity; to avoid damage to the structure this must also be connected to the conductors. A single air terminal is of no more use than an inscribed sign-board; besides multiplying the number of points, numerous paths, as well as interconnexions between the conductors, must be arranged to lead the discharge to the earth. The system of pipes and gutters on a roof must be imitated ”

“ Joints must be held together mechanically as well as electrically, and should be protected from the action of the air. At Westminster Abbey the cables are spliced and inserted in a box which is filled with lead run in when molten. ”