i am making a arduino project using 5v ws2812b 300leds/meter. Its going to be a motion activated led strip that runs along the side of the stairs. I will be using 3.5m of the led strip so 210leds at 60mA so if all white on full power they will consume 12.6 amps.

I have a 5v 40a meanwell power supply so plenty of overhead. I will put a 1000uf capacitor on the positive and ground leads of the wires just before they reach the leds and 480 ohm resistor on the data line.

I am concerned with voltage drop over 3.5 meters so i will run the wire along the led strip and inject power every meter. My question is what gauge wire should i be using?

The psu will be under the stairs so wire will be 5m long. I am worried about heat and would like some advice about any safety or fire concerns i should be thinking about.

Should there be a fuse in the circuit?

This is the best schematic i can find to show how its wired, where would the fuse go? Power is coming in from both ends of the led strip, would this suffice for a 3.5m strip

enter image description here

  • \$\begingroup\$ One chip consume 0.9-60mA, 300 LEDs will consume in max brightness 18A, 3.5 meters 63A. Thick wire you can not solder to strip, AWG#18 may be. Restrict brightness or make more connection points. \$\endgroup\$
    – user263983
    Apr 29, 2021 at 20:28
  • 1
    \$\begingroup\$ How is 300 LEDs/meter x 3.5 meters equal to 210 LEDS? There's a factor of 5 missing here. Did you mean 60 LEDs/meter? \$\endgroup\$
    – jcaron
    May 31, 2021 at 16:44
  • \$\begingroup\$ Do you plan on setting them to all white all together? if you want color or animation, you can get away with way less current, as long as you add something in code that stops them from accidentally be turned all on together. If you go that route, also add a fuse. \$\endgroup\$
    – Anas Malas
    Oct 5, 2022 at 6:13

2 Answers 2


My question is what gauge wire should I be using?

The recommended wire size for 13A is 19AWG (which is hard to find) so get 18AWG. 3.5m of 18AWG wire is about 0.12Ω, which would be about 1.5V of loss. So a larger size of cable or paralleling the wires (multiple strands of 18AWG) might be the best way to go.

Should you put a fuse in the circuit?

If you're worried about something shorting and heating up, then yes, put a fuse in. A 20A fuse would ensure that you don't blow the fuse but protect against short circuits.


It is usually recommended that you feed the power to the middle of long strips of LEDs. Or even to more than one point (for example both ends and the middle) in order to minimise the voltage drop along any one section of the run.

The advantages are that you can use thinner power distribution wires (the required total current is divided between the different sets of wires) and the illumination will be much more even.

The disadvantage is that you will have to run several power distribution wires.

  • \$\begingroup\$ How do you splice the wires to inject the led strip ? can you use them terminal blocks with the screws? \$\endgroup\$
    – stezoid
    Oct 28, 2019 at 19:10
  • \$\begingroup\$ @stezoid Most LED strips have places marked on them where you can cut safely. This should leave solder pads on each half of the cut so that you can make connections. If you google "cutting ws2812b led strips" you will find at least 3 videos and numerous links to web pages giving you full instructions. It is possible to buy solderless connectors to make the job easier. \$\endgroup\$ Oct 28, 2019 at 21:52

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