Why Voltage Drop Occurs In LED Lighting Strips

Feb 13 10:21 2012 Chris Horridge Print This Article

Voltage drop is a common occurrence within all types of electrical installations. When it occurs within LED lighting strips is fully visible as the colour starts to fade towards the end of the strip. This article explains the causes and the remedies for it.

Voltage drop or 'volt drop' happens 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 lighting strips 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,Guest Posting 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 metre 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 be reduced to 0% if greater distances were incorrectly attempted and cause permanent damage to the LEDs.

Volt drop in single colour strips are barley noticeable, especially in shorter lengths. Colour changing strips are more visible when you turn the colour to white. If there is not enough voltage towards the end of the strip the clear white colour will turn pink towards the end of the line. This is because white colour 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 don't get enough voltage and become weaker, whilst the red colour 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 metre strip can have a maximum run of 10 metres, compared to the 60 LED (14.4W) per metre strip which can have a maximum run of 5 metres.

This does not mean you can't install longer runs of LED strip, it just means that you need to take a different approach. Single colour strips and colour changing (known as RGB) strips are different because colour 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 colour strips should be wired directly back to the power supply in 5 metre of 10 metre runs depending on the version of strip i.e. 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 usually 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 metres in length as long as the power supply was rated appropriately.

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

For longer runs of colour changing strip, you need to fit amplifiers every 5 or 10 metres. 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 colour 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.

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About Article Author

Chris Horridge
Chris Horridge

Written by Chris Horridge, resident lighting expert for downlights direct for more information about LED lights, LED strips and downlights, please visit http://www.downlightsdirect.co.uk/led-strip.html

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