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I hope this is the right place for this!

I am trying to create addressable LED strip.

The strip will be 16m in total, running around the edge of the ceiling of the living room, like this:

LED coving

I am planning to daisy chain these strips together: WS2811 addressable LED strips

I have chosen WS2811 strips because these can be controlled by an ESP32 running WLED which can then be controlled by Home Assistant, which is ultimately how I want to run these. Also because WS2811 comes in 24V, whereas WS2812B only comes in 5V or 12V (as far as I know - please tell me if this is not correct!)

These WS2811 strips have a power consumption of 15W/m, so for 16m that would be a total of 240W. At 24V that is 10A.

I will need a power supply rated for at least 300W to give myself 20% overhead for safety.

I have three electrical questions, all safety related:

Question 1

I plan to power the 16m strip from both ends to avoid voltage drop and to avoid burning out the first LEDs in the strip. What does powering it from both ends do to the power supply? If I was powering it from only one end then I assume 240W would go in one end of the strip and travel 16m along the strip. If I power it from both ends will 120W go in each end and travel 8m along the strip to the middle? Is that right? Or is that not how it works? Most importantly, is doing it like this likely to be a fire hazard?

Question 2

My concern is that a 300W 24V power supply is pretty hefty and will get extremely warm. It is not going to be class II rated, so I would not be able to hide it in the wall without it being a fire risk. Are there any steps I can take to bury it in the wall without it being a risk? My primary concern here is not setting fire to my house. Hiding the ugly power supply comes second!

Question 3

Is there anything else I should be aware in terms of safety and not burning the place down?

Thank you in advance for any help!

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  • \$\begingroup\$ There's a lot there for others to deal with. But one thought I'd like to introduce to you is the idea of just using regular AC wiring in the walls (looking at your picture I can see you will NOT want to harm the walls but I'm addressing the heating issue you brought up.) You can just run the usual AC and lots of small AC-DC modules, one at each end of each strip. They should be reasonably efficient and dividing the dissipation like that will mean your 300 W is only 5 W here and 5 W there, which is not the same fire risk as 300 W right here. That way the fire risk is acceptably small. \$\endgroup\$
    – jonk
    Commented Nov 26, 2022 at 0:16
  • \$\begingroup\$ @jonk the risk will likely be a lot higher that way... also, 300w is not really much. Lots of small modules will be way worse in terms of efficiency, and it only needs one bad module to start a fire. The important thing here is to distribute the feed. I would not only power from 2 sides, but also feed from the middle (maybe several times) and use big enough wires so the voltage drop stays small and it also compensates for bad connections by having a bit of redundancy. \$\endgroup\$
    – Boldar
    Commented Nov 26, 2022 at 0:48
  • \$\begingroup\$ Also, why would the first leds burn out when powering from one side? That won't happen. What will definitely happen is that the last leds will be darker, and maybe the connector or traces will get damaged, although I think that is highly unlikely. \$\endgroup\$
    – Boldar
    Commented Nov 26, 2022 at 0:55
  • \$\begingroup\$ @Boldar could you explain why you think the fire risk would "likely be a lot higher" with Jonk's proposal? \$\endgroup\$ Commented Nov 26, 2022 at 1:04
  • \$\begingroup\$ Because you now have lots of cheap firehazard switching power supplies instead of one, and especially small, cheap ones are notorious bad and will likely lack basic protection, while it will be easier to get a decent 300w one \$\endgroup\$
    – Boldar
    Commented Nov 26, 2022 at 1:07

1 Answer 1

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Get a good UL rated switching supply and mount it in a proper steel NEMA enclosure, with appropriate input fusing, and output connections. Make sure the low voltage output wiring is adequate, and all connections need to be double checked to make sure they can't get loose or overheat.

NEMA Wall Mount Enclosures

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