Dear Ray
Why are my landscape lights dimmer at the far end of the yard?
Dear Ray, the first lights on my run look great, but the ones near the back fence are noticeably dimmer. Is that normal, or is something wrong?
— Watching the brightness fade
Dear Watching,
That pattern is common, and it is worth investigating. Your far fixtures are usually seeing less voltage than the first ones because the cable itself resists a little power over distance. That is called voltage drop, and it is especially noticeable on a long run with small wire or a lot of fixture load.
Start with the simple checks. Make sure every connector is dry, seated, and free of corrosion. A weak connection can make one fixture or a whole downstream section look tired. Then compare the transformer output with the voltage at the last fixture using a low-voltage meter. That tells you whether the problem is the run, not merely the bulb.
If the run is simply long, a few fixes can help: move some fixtures to a second branch, use a heavier cable, reduce the load on that branch, or use an available higher-voltage tap at the transformer. The voltage-drop calculator is useful before you start digging, because it lets you compare options on paper.
Do not solve this by replacing only the last bulbs with brighter ones. That can make the imbalance more obvious. A balanced run lets the whole yard look intentional, which is much nicer than a gradual retreat into darkness.
— Ray
If you want to go deeper