If you purchase or specify manual or automatic transfer switches, the subject of UL 1008 is bound to come up at some point. The UL 1008 listing is not just a performance standard, it is a design and construction standard in the industry. In order to receive a UL 1008 listing, a transfer switch requires rigorous testing by an independent certification agency. The certification is aimed at ensuring durability, reliability and safety during operation, and while this is an important listing, it is not truly understood by many.