It often happens in the construction site: an LED strip installed on a long stretch seems to lose brightness as you move away from the power supply point. It is not a product defect, nor a LED quality problem. It is a very specific physical phenomenon, which has a name: voltage drop.
Understanding what it is, and why the transition to 48V solves it almost completely, is essential for those who design or install linear lighting on large sizes: retail, offices, showrooms, large construction sites.
What is voltage drop
Each electrical conductor, however efficient, offers a small resistance to the passage of current. On short sections this resistance is negligible, but on long distances its effect accumulates: part of the voltage supplied by the power supply is “lost” along the route, in the form of heat dissipated in the conductor itself.
The practical result is that the LED strip installed near the power supply receives the correct rated voltage, while the most distant part receives a lower one. And since the brightness of the LEDs depends directly on the voltage that feeds them, the visual effect is a progressive loss of light intensity, the more marked the longer the line.
In simplified formula: the voltage drop is proportional to the current circulating in the conductor and to the resistance of the cable (which in turn depends on the length and section of the cable itself). The more current you need to feed a certain load, the more the fall is felt.
Because the problem gets worse with low-voltage systems
This is where the supply voltage comes into play. At the same power required, the lower the voltage, the higher the current to provide that power (it is the ratio P = V × I). And the higher the current, the more pronounced the voltage drop along the cable.
This is why traditional 12V or 24V systems show obvious limits on long distances: to illuminate 20-30 metres continuously, a high current would be needed, resulting in a significant drop in voltage and the need for intermediate power supplies to “relaunch” the signal along the route.
The 48V revolution
Moving on to a 48V system, the same power is supplied with a much lower current. Less current means, with the same cable, a drastically reduced voltage drop. The concrete result: a single power supply is enough to cover much longer stretches, with uniform brightness from the first to the last metre.
For those who design retail, offices or large commercial spaces, this is not a marginal technical detail: it means being able to draw continuous light paths of tens of metres without having to interrupt the project with intermediate feeding points, without darker areas towards the end of the route, and with an overall system that is easier to install and maintain.
Because it counts, in practice
Voltage drop is not just an electrical engineering textbook concept: it is the difference between a system that runs smoothly over its entire length and one that requires compromises, additional power supplies and longer installation times. Knowing this phenomenon helps to understand why, on large sizes, the transition to 48V is not a technical fashion, but a choice that concretely simplifies the work of those who design and install linear lighting.