Current ratings and voltage drop for low voltage LED power supply cabling

01 May 2022 | all notes

WS2812B-controlled LEDs run on a supply voltage of 3.5 - 5.3V DC. Assuming you have a sufficiently strong 5V power supply, how much of an extension chord can you get away with between the supply and the LEDs?

As an example use case I had four NeoMatrix 8x32 RGB matrices where at any given time a total of 126 pixels were lit up, with RGB mixing never having more than two of the basic colors fully lit:

Max consumption = 1024 * 1mA per-pixel baseline + 126 * 40mA LED consumption ~ 6 Ampere total

Typical extension chords with a 5.5/2.1mm plug use either 20 or 22 AWG copper wires. For each type of wire there is a fixed voltage drop per Ampere per meter (see RapidTables voltage drop calculator). Maximum current rating depends on many other factors (type of insulation, number of cores etc), but if a cable’s rating is in the ballpark of the values below it should be alright:

AWG mm^2 Ohm / km DC Voltage drop (two-way total!) Current rating: very very conservative Typical Max. Current Load Rating (up to 3 cores) Single core
20 ~ .5 33 .066V per Ampere per meter 1.5A 5A 6A
22 ~ .3 53 .1V per Ampere per meter .92A 3A 5A

Product examples:

2.1mm or 2.5mm pin?

jemenake says:

A 2.1mm receptacle:

A 2.5mm receptacle: