I'm setting up new strip lights in my room, and I'm upgrading from solid color to individually addressable, and I'm not very good at dealing with power while making sure that nothing gets damaged. I know how to program the arduino and solder so I won't need any help with that. I plan to either use around 42 feet of these, but if those ~750-900 lights are too much to handle for the arduino, then I'll use these. I have an Arduino Nano, 2 Unos (one of them is an Elegoo), and an Elegoo Mega 2560. The strip lights have pre-wired in and out connectors so you can chain them together, and they have extra wires to add voltage at the end of each strip. I'm really excited about this project and since I don't have a job it's not a cheap project either, so I want to make sure i do this safely and correctly. What precautions and things (like fuses, resistors, ect) should I get to make this and how should I go about wiring this stuff. I can provide any extra needed information as requested
Read the information a bit down. It tells, 5 volt supply, 20, 40 or 60 mA per LED depending on how many colours are On.
The total current depends on how many LEDs are active at the same time. Calculating 900 x 0.06 A = 54 Amps calls for a giant power supply. That can't be what You must go for.
One tip: For long chains input current regularly, not only at the ends. Use a "solid" supply line along the strip. Know that both +5 and GND needs the same thinking.
You need to think through the patterns You intend to run.
I read that stuff, but I didn't fully know what that entails. So would 450 lights be more realistic (it would probably be around 350-400 lights after cutting to the right size of my room)
I don't fully understand Your question. The advice given still stand: You need to consider the amount of LEDs being activated at the same time.
Depending on how You generate the patterns different amount of controller memory will be needed. If for example a for loop generates the signals not much memory is needed. If tabells with patterns are used more memory will be needed. How much depends on what You want to show.
Regarding the power supplying know that several supplies can be used having their negative wire wired together. The LEDs being incapsulated power feeding must be applied to the ends.
I don't really have an estimate of how many LEDs are going to be on at once at a time other than "all" because what I'm going for is to use them for different things when I feel like it. I now understand how hard it is to get that much power as well.
For the power stuff, you insert parallel voltage to the +5v in different spots in the chain right? And for ground, it all needs to go to the same thing right?
Let me rephrase that, I never expect to have more than 10% of the LEDs to be white at any given time, closest to that is a light blue.
Another thing is that would it be possible to have 3 different power supplies, one for each strip, but still have the one Arduino control all 3 of them (I'm not worrying about ram rn)
Okey. Go for a 10 or 20 Amp, 5 volt power supply.
You can start some limited testing using one strip. Having a DMM, digital multimeter You can inspect the voltages and check the voltage at various points. Then add the next strip and check.
Okay, the only thing that loss in voltage does is make the lights not as vibrant later in the chain correct? Does it damage anything if you lose voltage?
Sorry for being stupid at this
Yes. Reading my previous reply there's no problem to use one power supply.
Yes. Usually the illumination goes lower if the power injection is insufficient.
Damages..... As I've got it, never heard about smoke signals...
Not at all. Every beginner is ignorant in the beginning. That's what this forum is her for, helping members to learn and grow.
Thank you for your help. I will get the lights and a power source, and in the meantime I will be doing more research about this. I'll let you know how things turn out 
54 amps times 5V = 270 W.
Half if this will be converted to heat in the current limiting resistors... (the 12V ledstrips that are addressable in blocks are way more economic... ).
The other half will still be 135W of led light.
That will be pretty bright...
Good that OP already chosecto go for 10% of max brightness.
54 amps would be a current that might easily cause a fire in case of a short cut. This thing needs a proper fuse! And that may not even work since a resistance of 0.1 ohm is sufficient to keep the current below 50 amps...(still generating 250W in that 0.1 ohm).
I was talking with my dad and he brought up that even just 20a would probably destroy the lights. Is this true, and if so why do the WS2812B LEDs take so much power
Current (xxxA) is pulled by the LEDS, not pushed by the power supply.Its just ‘available’.
The only damage caused by a ‘too big’ power supply is to your wallet, and anything that falls across the +/- conductors that might draw more current than the supply or conductors can ‘push’.
Actually what you'll notice is that the LEDs will start to show a reddish hue. That's because there are individual red, green and blue LEDs in each unit, and the red one operates on a lower voltage than the others, so if the voltage dips, you lose the green and blue first.
And "why do the WS2812B LEDs take so much power?" Because you have a lot of them!
I think I'm not using the strip lights for the intended purpose. Thank you all for the help and information, I'm just going to buy some segmented ones that already come with everything needed
You have two options:
- plan for worst case scenario: 300 LED's per strip would require 18A (300 x 60 mA per LED). This is best practise, which covers all LED's full on white.
- Pick what you want and risk blowing a power supply.
Pick a fuse rated 20% lower than the max supply rating, then only item 1. and the physical wires are at risk.
Who said pile on?! I'm in! Just kidding. Once you solve the power-over-15-meters, you will need to address timing and memory usege. The Uno and Nano can handle around 600 neopixels before memory issues happen. Timing - sending 24-bit color signatures to each individual pixel and to the end of a long string starts missing pixels or mixing colors... I am not saying it can not happen, because you have seen massive, private, light-shows, but those things are not usually made in a hobby shop, but purchased at thousands of Swiss Franc. The COTS (commercial-off-the-shelf) products that only need power and a battery for the remote control are quality, flexible, IP67 and have sticky tape on the back. They can be hidden from view and any of their patterns and colors can be called up with the remote. Have fun with it!