Am I not understanding something correctly here?
I am looking to run WS2812B (5v, 60 LED’s/meter) around my bed and headboard, a total of 36 feet.
According to online calculators, I will need a power supply that puts out 40 AMPS. Other resources then say that 40 AMP’s require 8 AWG wire.
40 AMPs and 8 AWG wire just doesnt seem do-able or prudent. Am I not understanding something correctly? How do I get lights aroundy my bed without requiring a nuclear reactor in my house?
For that long of a strip, you will need to do power injection at multiple points. That is, adding additional power wires to the strip every 5 or so meters going back to the power supply (or power bus). Those thin strips just won’t carry that much power from one end to the other and you’ll get all sorts of unwanted effects (colors fade towards the end furthest from the power source).
You could have a pair of 8AWG power wires running along your strip from the power supply and tap into those power lines every x meters and tie it to your strip with 18-20AWG at the junctions.
But, that 40A is for full brightness of all 3 color channels at the same time (white). The vast majority of the time you’ll likely be running effects which require a fraction of that power. If you don’t intend to do white full brightness, you could put a power limit in the software of something like 20A and gauge your power cable accordingly. You will still need power injection for that length of strip no matter what. Those traces on the strip carrying power are tiny.
Yeah, not planning to do white, full brightness.
Well for a start 40A at 5V is only 80W. Not much power. 200W. Though yes, high current at that low voltage, make sure you fuse the power cables.
36ft is 2x 5m strips. Feed each strip at each end (4 sets of power connections). That’s only 10A required for each set of power wires. Much more manageable (17AWG / 1mm2).
EDIT: There’s some real world power requirement test data here: https://quinled.info/2020/03/12/digital-led-power-usage/ if you don’t plan on running 100% white all the time.
Are you getting 10A per 5M strip based on me not running white at 100% brightness?
And kind of off topic, but for bed lighting do you think I need 60 per meter, or could i get away with 30?
Nope, I was using your specified requirement. The data I linked to suggests 65W per 5m (130W total for two strips) at 100% RGB white.
The rainbow effect is only 50W for two 5m strips (2.5A rating ea for 4 sets of power wires).
There are also “Eco” strips that use less power. See the link.
How far away from the floor/ illuminated surface are the LEDs?
The further away they are the less LEDs/m you need to maintain even illumination. See: 30 vs 60 vs 90 vs 144 LEDs/m - quinled.info
About 8-10 inches from the floor/wall
30 LEDs / m should be ok for that.
If you find it isn’t you can always install a diffuser (you should have your LEDs in aluminium channel for cooling anyway).
Ohhh, I see. Feed strips at each end. So if the strip needs 20A and I feed it 10A at each end, the wires would only need to be sized to carry 10A. Gotcha.
So I picked up WS2812b, which chart shows at 47watt at full white.
47watts @ 5v is ~10A for 300 LEDS.
If I have 700 LEDS thats ~24amps for all of them.
If I inject power at 6 points in the 35meter run, I’d only need 4 ampacity wires for each; 6 just to be safe. Am I thinking correctly there?
Also I need to inject power and ground , correct?
Yes that’s correct and yes you need both power and return (ground).
P = U x I
So 40A at 5V is actually 200W, which is quite high.
Indeed it is. Not sure where my brain was.