LED Strip Voltage Drop

Voltage drop or 'volt drop' occurs in all types of electrical installations. When larger power cables are being installed more complex calculations must be made to counteract the problem. However when LED strips or tapes are concerned there are a few simple guidelines to follow. Volt drop in LED strips occurs when the LEDs are…

Voltage drop or 'volt drop' occurs in all types of electrical installations. When larger power cables are being installed more complex calculations must be made to counteract the problem. However when LED strips or tapes are concerned there are a few simple guidelines to follow.

Volt drop in LED strips occurs when the LEDs are positioned too far away from the power source or when longer individual runs (or lines) are attempted. This happens because not enough power or electrical current reaches the LEDs, because it has further to travel. This causes the voltage to decline or drop towards the end of the run.

Voltage drops out approximately 0.6V every metre and is less noticeable with 24V strips. When using 12V strips, a 2-3V drop over a 5 meter run would reduce the voltage by 25% subsequently reducing the lumen (brightness) by a similar percentage.

Volt drop could be compared to a person climbing a mountain, the higher the altitude, the thinner the oxygen becomes and the less the person can breathe.

The LEDs at the start of the line will appear bright at 100% output but the LEDs towards the end of the line will start to fade. The brightness will reduce exponentially; the further away it gets away from the power source. Potentially the light output could have reduced to 0% if greater distances were incorrectly attempted and cause permanent damage to the LEDs.

Volt drop in single color strips are barley noticeable, especially in shorter lengths. Color changing strips are more visible when you turn the color to white. If there is not enough voltage towards the end of the strip the clear white color will turn pink towards the end of the line. This is because white color is mixed from red, green and blue (RGB). However, the red requires less voltage than green and blue. When the strip is far from the power supply, green and blue do not get enough voltage and become weaker, while the red color becomes more prominent and turns white into pink.

The higher the wattage of the LED strip, the short the run should be. For example; 30 LED (7.2W) per meter strip can have a maximum run of 10 meters, compared to the 60 LED (14.4W) per meter strip which can have a maximum run of 5 meters.

This does not mean you can not install longer runs of LED strip, it just means that you need to take a different approach. Single color strips and color changing (known as RGB) strips are different because color changing strips need to be controlled from one controller. Using a higher rated power supply does not fix the problem as the current still has to pass through a long line of LEDs and resistors, each one draining small amounts of power.

Single color strips should be wired directly back to the power supply in 5 meters of 10 meters runs depending on the version of strip ie 30 or 60 LED that is used. Each run will be powered directly from the power supply and can be turned on or off by switching a switch or unplugging it from the mains. The power supply is typically wired to a light switch but could be controlled by various types of controllers. The strips can then be positioned however you like, in one long line or in a rectangle shape for example. Once the strips are positioned next to one another the light will appear seamless, like a fluorescent tube. The run could be over 100 meters in length as long as the power supply was rated appropriately.

Volt drop will occur slowly in the connecting power cables but as there are no LEDs or resistors etc draining the current, the volt drop will be barley noticeable. Thicker cables can be used to reach further distances.

For longer runs of color changing strip, you need to fit amplifiers every 5 or 10 meters. Amplifiers allow the strips to be powered indirectly from the power supply but also allow the signal from the controller to pass through the entire run of strips. This way when you turn the color to red for example, everything turns to red at the same time. The amplifiers power the strip, the power supply powers the amplifiers. Amplifiers can even be powered from their own separate power supply and you could have as many power supplies as you like on the same run. The power supplies can be positioned closer to the LED strip connection or wherever is most accessible.

For longer, more complicated runs we can supply our customers with their own easy to follow wiring diagram. The diagram illustrates how the power supply, strips and cables are connected together. As part for our LED Strip Fit brand, LED strips can be supplied to the exact lengths required; everything apart from the larger hard wired power supplies can be plugged into each, requiring no tools or electrical knowledge.