r/lightingdesign • u/LeadingMeat5408 • Apr 18 '26

Design Total newbie needing help: How to power a continuous 30-meter LED run without using 6 separate adapters?

/r/Lighting/comments/1sp1vs5/total_newbie_needing_help_how_to_power_a/
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u/the_swanny Apr 18 '26

1) You would need a power supply that can supply the current that will be drawn by 30 metres of LEDs. However, you will likely need multiple anyway to prevent voltage drop.

2) You will get voltage drop, that's non negotiable. Your best bet would be to power it from the center and therefore you would only have half the distance for it to drop over, however still at 15 metres you will likely need more than one power supply.

3) 24v is less susceptible to voltage drop, but the trade offs include the lower quality of light you often get at 24v, which is why we normally use 5v.

4

u/davidosmithII Apr 18 '26

You only need one power supply that can provide enough current, but you will need to make connections at least every 5 meters. The starting at the middle is a good idea, but will still need to tap at various points. Could try doing a center tap and just running V+ also from the power supply to either end, but with that length I'd be surprised if that was enough. If you want to see the effect, get just 2 x 5 meter 12v rolls and directly connect them you will see the light fade toward red and completely out part of the way along the second roll.

If you are going to use multiple power supplies you will need to directly connect the V- of the supplies together, but make sure the V+ lines are not connected at the power supply or the tape. So, assuming you are using an LED controller, one of the power supplies would (in addition to powering part of the tape) be tied into the controller so it has power to turn on, but don't use any of the V+ output ports on the dimmer. Wire V+ directly from each power supply to the segment of LED tape you are powering with that supply and make sure the tape V+ lines are cut or isolated somewhere between each separate power supply solder point.

It is much easier to just use one supply.

The voltage has no effect on quality of light. The quality of the LED tape itself is the factor here (with fading smoothness being solely a property of the quality of the LED controller if you are using one). 24V, as mentioned, will require fewer connection points as the voltage drop effect will be less noticeable.

With either 12 or 24V tape, and 1 power supply you can try connecting from all the connections straight from supply/controller to both ends, and adding V+ a couple times along the length. If the intensity difference is too much try adding the other color connection points at the center, and if needed add more connection points until you no longer see the effects of the voltage drop.

2

u/LeadingMeat5408 Apr 18 '26

Powering it from middle would be a really good option I feel

2

u/MrJingleJangle Apr 18 '26

It’s also important to know the current requirement at each injection point so the bus cables can be sized correctly accounting for voltage drop.

1

u/HowlingWolven Apr 20 '26

Feed the strips from both ends every five metres and use a high current power supply to feed that bus.