How should LED streetlights be grounded for lightning protection?
As outdoor equipment installed at height, LED streetlights must be equipped with a reliable lightning protection and grounding system. The specific requirements are as follows:
1. Pole Grounding: Metal light poles must be reliably connected to the earth via grounding steel bars embedded in the foundation. The grounding resistance should be ≤4Ω (or ≤10Ω in areas with high soil resistivity). Each pole must have at least one grounding electrode—such as a galvanized angle steel bar or a copper-clad steel rod—driven into the ground.
2. Luminaire Grounding: The metal housing of the luminaire must be electrically connected to the light pole (using a grounding wire) to ensure that the luminaire is grounded whenever the pole is grounded.
3. Surge Protective Devices (SPD): SPDs should be installed in the street lighting distribution box and at the input side of the driver for each individual lamp (or each circuit). A Type 2 SPD is recommended, with a nominal discharge current of 10kA (8/20μs) and a protection voltage level of ≤1.5kV. The SPD should feature a failure indicator and a thermal disconnection mechanism.
4. Equipotential Bonding: All metal components within the light pole—including the pole itself, cable shielding, and grounding wires—should be interconnected.
5. Lightning Rods: For standalone tall poles (≥15 meters) located in open areas, the installation of a lightning rod is recommended, connected to the grounding network via a dedicated down-conductor.
6. Cable Selection: Use cables with metal armor or shielding, and ensure that the shielding layer is grounded at both ends.
7. Periodic Testing: Grounding resistance should be tested annually before the rainy season, and the status indicators on the SPDs should be checked to ensure they are functioning correctly. A proper lightning protection and grounding system can significantly reduce the risk of damage caused by lightning strikes.
