Specifications include, but are not limited to: This specification describes the minimum requirements for a Battery Backup System (BBU) for Traffic Signal. The BBU System consists of three modules within an enclosed cabinet: Inverter/Charger Bypass Switch Battery Bank A. The BBU System shall be certified per UL 1778. All elements of the System shall comply with the applicable code sections of the NEC, NEMA, and OSHA. B. The BBU System shall operate using the Line Interactive (Buck and Boost) method. C. The BBU System shall be capable of operating a signalized intersection (700-watt load) for four hours of full runtime when utility power is disabled and under ambient temperatures of 25°C. D. The BBU system shall switch the intersection to flash mode of operation when approximately 40% of battery charge is remaining via relay contact connection points on the front panel of the inverter/charger unit. The BBU System shall operate the intersection in the flash mode of operation (350-watt load) for an additional two hours.