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LED Strip Light Voltage Drop, What is Voltage Drop?

LED Strip Light Voltage Drop: What is LED voltage Drop and how to fix it.

One of the most important things to consider when installing LED Strip lights is the effect of what is called “voltage drop”. Basically, the longer the length from a light to the transformer, the lower the resulting voltage. Our LEDs require 12 volts at the light fixture itself; any LED strip lights that are installed a few feet away from their power source, but very long strip light lengths call for careful voltage testing at the strip.

Example: If you are running over 40 feet of ColorBright™ LED strip light, or are using a long length of wire from the power source to the strip, the LEDs on the end of the strip may appear dimmer than the LEDs near the front. You would need to cut the strip at about 24-28 feet and insert another 12V DC with a solderless connector. The below diagram is from Elemental LEDs, and provides an example of how to do a long LED installation.


voltage drop for 12v led strip lights

Maximum current - amps - through a 12V circuit in combination with size (AWG) and length of wire


To figure out which gauge wire you should use, see the chart below.

In an electrical system, the conductors should not be sized with voltage drops exceeding 3%. For a 12V system, the maximum voltage drop should be less than 12 (V) x 3% = 0.36 (V).

The table below can be used to determine the combination of maximum current through a 12V electrical wire, size (AWG) and length of cable.

voltage drop and wire gauge size calculation for 12v LED strip lights

Note! Failure to use an adequate size may result in fire. Always secure a wire with a fuse.

1 ft (foot) = 0.3048 meters

Wire Gauge Design Procedure

1. Calculate the total length of the wire from the source to the device and back again.
2. Determine the amount of current in the wire.
3. Correct wire gauge is in the intersection of amps and feet seen above.

Note! The wire size is required for a 3% voltage drop in 12 Volt circuits. Oversize the wire if the voltage drop is critical.

VOLTAGE DROP AUTOMATIC CALCULATOR HERE --> http://www.supercircuits.com/resources/tools/voltageDrop

Tips on how avoid Voltage Drop in LED Strip Lighting

There ar a few things you can do to avoid voltage drop in some situations. Voltage drop will vary based on the brand and power consumption of the LED strip lights. 12V LED strips dent to lose voltage faster then 24V, so if you are looking for longer runs, but have power supply concerns (you can only install one), we would recommend going with the 24V strips. 

Here are a few things you can do:

1. Install the LED strip lights in parallel from the power unit itself

If you needed 50 feet of 24V Ultrabright LED strip lighting in bar or patio, we would recommend installing the power unit in the middle of the run and having one 25ft section running from the power supply to the left, and one 25ft section going to the right. Since they are both hooke dup independently, there is less of a chance of voltage drop than if you were to run 50ft in series.

2. Use seperate power supplies in different areas

The Long Beach Airport installed a long run of our LED strip lights and had to use (2) power units on each side of the run. The strip is not connected in the middle and you can see there is no visible voltage drop.

Long beach airport terminal LED install by Flexfire LEDs

3. Run extra wire in parallel

Run an extra wire of 12 or 24 V form the power unit (high gauge wire) and reattach it to the next run of LED strip lights to insert more power into the line.

If you have questions or comments on an install, our project design team would love to assist you!

Please call us 925-273-9080 or email Info@flexfireleds.com