Transformer capacity is one of the easiest parts of a low-voltage lighting project to oversize or undersize. The basic calculation starts with total fixture wattage, but cable length, voltage drop, number of runs, and future expansion can change the practical choice.
Start with connected load
Multiply the wattage of each lamp by the number of fixtures, then add every run together. Ten 5W lamps create a 50W connected load before any design margin is added.
Leave useful headroom
Running a transformer at its absolute nameplate limit leaves little room for additions and can make design changes harder. Choose enough capacity for the planned fixtures plus sensible expansion, without treating a very large transformer as a substitute for proper circuit design.
Long cable runs can become the real constraint
Voltage drop increases with current and distance. Larger projects often benefit from multiple shorter runs, appropriate wire gauge, and multi-tap transformers rather than one long daisy chain.
Kit sizing can simplify the first pass
Gardenreet currently pairs different fixture counts with 75W, 150W, and 300W transformer configurations. Those bundles provide a useful starting point, but the final layout and run lengths still need to be checked.
How we research outdoor lighting
We compare fixture material, voltage, lamp serviceability, beam type, transformer capacity, cable specification, weather protection, controls, warranty, installation requirements, and the total system needed to light the site safely and consistently.
Prices, specifications, firmware, inventory, and configuration-driven features can change. Check the current manufacturer or retailer page and local requirements before buying or installing equipment.