The rules:

- All power values are taken from the Real-World Power sheet from https://quinled.info
- We're going to calculate with a nominal current (RGB White 50% value) (See Article: https://quinled.info/2020/03/12/digital-led-power-usage/)
- An edge injection point can do about 4Amps and a middle injection point about 8Amps (See Article: https://quinled.info/should-you-replace-wires-on-led-strip/)
- A power injection wire should not have more then 10% voltage drop on that wire. (Voltage drop calculator https://www.rapidtables.com/calc/wire/voltage-drop-calculator.html)

Scenario 1: 5v, 20m/64ft, ws2812b, 60LEDs/m
Scenario 2: 12v, 20m/64ft, ws2815, 60LEDs/m
Scenario 3: 24v, 20m/64ft, ws2811, 720LEDs/m COB LED strip

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SCENARIO 1: 5v - 20m/64ft
5m/16t nominally uses: 35w
20m/65ft nominally uses: 140w at 5v!
Recommended Power supply = 140w + 20% = 168w (so probably get 200w)

Watts to Amps:
140w / 5v = 28Amps

!! Added end injection vs video! For 5v strip to make sure there is no drop during nominal usage it's best to have a front + end injection for each 5m strip!
*notes injection point*
*front* |strip| *middle* |strip| *middle* |strip| *middle* |strip| *end*

front = 4Amps
1st Middle = 8Amps
2nd Middle = 8Amps
3rd Middle = 8Amps
end = 4Amps
Max delivery potential: 4+8+8+8+4 = 32Amps!

Fusing:
4Amp should get 5Amp fuse
8Amp should get 10Amp fuse

front = 1m
1st Middle = 6m
2nd Middle = 11m
3rd Middle = 16m
end = 21m

front = 20AWG/0.51mm2
1st Middle = 12AWG/3.30mm2
2nd Middle = 10AWG/5.26mm2
3rd Middle = 8AWG/8.36mm2
end = 10AWG/5.26mm2
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SCENARIO 2: 12v - 20m/64ft
5m/16ft uses 50w
20m/64ft uses 200w
Recommended power supply 250w+

Watts to Amps:
200w / 12v = 16,66Amps

*notes injection point*
*front* |strip| middle |strip| *middle* |strip| middle |strip| *end*

front = 4Amps
middle = 8Amps
end = 4Amps
Max delivery potential: 4+8+4 = 16Amps

front = 1m
middle = 11m 
end = 1m

front = 20AWG
middle = 12AWG
end = 20AWG

end (16m) = 14AWG

Fusing:
4Amp should get 5Amp fuse
8Amp should get 10Amp fuse

Alternative option: (controller in the middle option!)
*notes injection point*
#notes Data+GND connection#
#front# |strip| *middle* |strip| middle |strip| *middle* |strip| end

Middle1 = 8Amps
Middle2 = 8Amps
Max delivery potential: 8+8 = 16Amps

Middle1 = 6m
Middle2 = 6m

Middle1 = 16AWG/1.30mm2
Middle2 = 16AWG/1.30mm2
(extra wire for data+GND to front 11m)
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SCENARIO 3: 24v - 20m/64ft 
5m/16ft uses 60w
20m/64 uses 240w!
Recommended power supply 240w * 1,2 = 288w (so get a 300w)

Watts to Amps:
240w / 24v = 10Amps

**Cheat mode on!** (The bare minimum...)
5m uses 45w
20m uses 180w
180w / 24v = 7,50Amps

*notes injection point*
*front* |strip| middle |strip| middle |strip| middle |strip| *end*

front = 4Amps
end = 4Amps

front = 1m
end = 1m

front = 20AWG/0.51mm2
end = 20AWG/0.51mm2
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Scenario 3 ULTRA MODE: !100% RGB WHITE ALL THE TIME!
5m is 112w
20m is 448w
Recommended Power Supply is 448w + 20% = 537w (but around 500w is likely fine since we are calculating a max usage scenario)

Watts to Amps:
448w / 24v = 18.66Amps

*front* |strip| middle |strip| *middle* |strip| middle |strip| *end*

front = 4Amps
middle = 8Amps
end = 4Amps
Max delivery potential: 4+8+4 = 16Amps (close enough!)

front = 1m
middle = 11m 
end = 1m

front = 20AWG/0.51mm2
middle = 16AWG/1.30mm2
end = 20AWG/0.51mm2
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Do I need multiple data connections?
(See Article: https://quinled.info/2021/03/23/max-amount-of-addressable-leds/)
Scenario 1: yes we need 2 (2x 600LEDs)
Scenario 2: yes we need 2 (2x 600LEDs)
Scenario 3: No... 1x 5m = 100 addressable zones x4 = 400 zones!

33R resistor mode
(See Article: https://quinled.info/data-signal-cable-conditioning/)
2-wire + separate data = 249R (default mode)
3-wire cable = 33R