Impact of Lightning on Street Lights - An experimental study investigating different poles and cables

Full scale experiments aiming at lightning protection of road lamps have been carried out. Two full scale systems of road lamps have been built built. One system was enclosed in a Faraday cage metal shielding, and the other system without any metal shielding. Each system consisted of four LED lamps on poles, 40 m from each other. The system using the Faraday cage was made of metal lamp houses, metal lamp poles, and shielded cables for power delivery. The alternative system was made of composite plastic lamp poles and unshielded cables. Lightning impulses were delivered by a surge generator, and the pulses injected at the lamp house, at the cable shield, and at the protective earth conductor. The evaluation was made by comparing the response voltages at the LED-lamps of the two alternative systems. The value of the resistance between protective earth and ground was studied. There was not a really decisive advantage with the Faraday-cage system compared to the completely unprotected composite plastic system. The reason is estimated to be cross coupling inside the lamp poles, and the too sparse shielding of the shielded cable.