How can I protect my employees in an outdoor working environment, and how can I calculate the earth ohms for the lightning protection system?
Three potential problem areas need to be addressed. Direct strike protection is necessary in an open area. Mounting poles or masts at a significant height above the workmen can provide this. If the poles are metallic, they can be grounded near their base. If they are wooden, an air terminal and cable conductor should be run to a grounding connection at grade. Masts generally cover a ground area of radius equal to their height (not exactly, but approximately), so that will provide a number and spacing. A second item would be side-flash potential (the ability of lightning to jump from it’s initial path to some other grounded body). Personnel should be protected from touching the conductors at the time a lightning strike occurs. Cable can be enclosed in nonmetallic conduit or wood molding to a height that personnel cannot reach. Finally, when lightning reaches the earth, it spreads out on the surface creating an electrified field. Personnel located in this ground area can be knocked off t
