Hi Jerry, thank you for your question regarding Trex Outdoor Lighting. The amount of lights per transformer will depend on the type of light and type of transformer. Page 7 of [Trex's Outdoor Lighting Brochure](https://www.diyhomecenter.com/media/pdf/trex-outdoor-lighting-brochure.pdf) shows the maximum number of each individual light fixture type per transformer. [Trex's Lighting Transformer Calculator](https://www.trex.com/build-your-deck/planyourdeck/lighting-calculator/) also makes it easy to figure out.