What Is Voltage Drop?

Voltage drop is defined as the amount of voltage loss that occurs through all or part of a circuit due to impedance. Wires, electrical components, and virtually anything carrying current will always have inherent resistance, or impedance, to current flow.

How can voltage drop affect an LED lighting system?
The importance of voltage drop for LED based lighting is that an LED requires a minimum amount of current to properly light. Less than the minimum current can cause an LED to flicker, operate less brightly, or shift in the color. This is often noticed in longer runs of LED tape light. The result is a perceivable shift in color or brightness difference in the LEDs on one end compared to the other.

How can customers avoid voltage drop effects with Diode LED solutions?
This may be best demonstrated with an example using Diode LED Tape Light. The specifications show that it can run up to 40 feet. Let’s make that work using the simple steps below.

1. Calculate the wattage required.
The specifications state that the Diode LED Tape Light uses 2.09 Watts per foot. Diode LED tests the voltage drop within products and designates maximum runs. If you stay within the tested maximum run length, simply calculate the wattage per foot or per fixture to determine the proper driver capacity. The maximum run of 40 feet will require at least 83.6 Watts to properly power the LED tape light array. (2.09 Watts per foot x 40 feet = 83.6 Watts)

2. Identify proper wire gauge to run between the driver and LED luminaire.
Diode LED products will only work as specified provided there is 3% or less drop in voltage between the Driver and the LED lights. The degree of voltage drop is determined by four main factors: voltage input (12V or 24V), wire run length, wire gauge, and total fixture load used by the lighting (Watts & amps).

An electrician or installer can use the chart below to determine the proper wire gauge for the installation. If in our example the driver is installed 20 feet from the Diode LED Tape light the second chart shows that the correct wire gauge is 16 AWG.

Voltage drop charts for Diode LED LED tape lights can be found on their product pages.

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