Feeding Long Strips: Parallel Taps, Load Sharing, and Balanced Wiring

A single LED strip run beyond a few metres is not one load; it is a conductor carrying current that is being drawn all along its length. The way that current is delivered determines whether every metre glows evenly or the far end fades. The discipline of feeding long runs is about recognising where the copper stops being a wire and starts being a voltage-dropping resistance.

The fundamental limit is the product of current and resistance. Every metre of strip draws its share of current, and every metre of the supply conductor carries all the current drawn by every metre beyond it. Near the driver, the conductor carries the whole load; at the far end, it carries only its own metre. The accumulated voltage drop is worst at the far end, and because LED strips need a minimum voltage to regulate properly, the symptom is a warm, dim tail that grows with distance.

The standard solution is to feed the strip from multiple tap points rather than from one end. Instead of one long conductor carrying the full load, the installer runs separate feeds from the driver (or from a distribution point) to several evenly spaced connection points along the strip. Each segment then sees a short, low-drop feed, and the voltage across the whole run stays within the strip's regulation window. This is the difference between a 5-metre one-end feed and a 10-metre double-ended feed: the latter halves the worst-case voltage drop.

Load sharing between parallel feeds is the subtle part. If two conductors feed the same strip from opposite ends, the current splits between them in inverse proportion to their resistance. That is usually fine, but if one feed is thicker, shorter, or better connected than the other, it carries more current and runs hotter. The balance is not automatic; it is determined by the wiring, and an unbalanced feed concentrates the current and the heat in one path. The engineering intent is to make the two paths as equal as possible.

The current a driver can actually deliver at the far end of a long cable is also limited by the driver's regulation. A constant-voltage driver holds the voltage at its own terminals; it cannot hold it at the end of a thin cable. This is why datasheets specify a maximum output cable length, and why the voltage must be measured at the strip, not at the driver. For runs that exceed the practical limit, the options are thicker wire, a higher-voltage rail such as 48 V to cut the current, or moving the driver closer to the centre of the load.

There is a balance between driver count and wire cost. One large driver feeding the centre of a long run uses less copper than several small drivers distributed along it, but a single driver is a single point of failure. For a façade or a corridor where a dark section is unacceptable, two drivers feeding opposite ends of the run provide both balanced voltage and redundancy: if one fails, the other still lights its half. The wiring design, not the driver, decides whether the run stays even when a driver drops out.