Lightning Risk Assessment for Street Lighting Systems

Street and area lighting systems can be damaged by lightning activity in their vicinity. This damage can occur as a result of a direct strike to a pole or luminaire, surges resulting from a strike to power lines feeding the circuits powering the lighting system, and induced surges on underground power lines (the most likely scenario). This study addresses each of these scenarios considering the cases where there is no lightning protection or surge protection provided on the poles, and with varying levels of surge protection installed. In order to provide protection against direct strikes, a lightning protection system should be installed but this is not often the case even when a metal pole is used. In many cases the pole and associated lighting circuits hit by lightning is lost but in addition a lot of problems will arise on other poles from surges generated by the strike. As a result, this discussion focuses mainly on surges and on the risk of loss of service to the public (R2) in accordance with IEC Standard 62305-2. Edition 2. The analysis will focus on determining the sensitivity of lighting systems due to overvoltages and the statistical benefit to survivability gained by the installation of surge protective measures. Specific examples are discussed, based on a comparison of systems incorporating high-intensity discharge (HID) lamps versus lighting systems incorporating LED technologies. The assessment also addresses an economic analysis based on the cost of the damaged material and expenses related to the repairs required to restore the service. Based on the assumptions made in the examples, a simplified risk assessment method has been developed to determine the benefit of using Surge Protective Devices on lighting circuits based on the lightning ground flash density, type of lighting technology used, and length of cabling of the lighting system.