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⚠ The three rules of LED-strip power.
1. Never power a long strip from one end — the flex copper drops volts; the far LEDs shift color or flicker. Inject along the run.
2. Common ground between the supply, the strip and the microcontroller. A level shifter on the data line (3.3→5V) fixes most glitching.
3. Fuse the supply line near the PSU. Strips fail short; an unfused 5V 20A supply is a fire risk.
2. Common ground between the supply, the strip and the microcontroller. A level shifter on the data line (3.3→5V) fixes most glitching.
3. Fuse the supply line near the PSU. Strips fail short; an unfused 5V 20A supply is a fire risk.
Injection & wire guide
| Run length (5V, 60 LED/m) | Power injection | Feed wire (worst case) |
|---|---|---|
| ≤ 2 m | One feed at the start is fine | 18 AWG (0.75 mm²) |
| 2–5 m | Feed both ends | 16 AWG (1.5 mm²) |
| 5–10 m | Feed every 2–3 m + both ends | 14 AWG (2.5 mm²) bus, 18 AWG taps |
| 10 m+ | Split into segments with separate supplies, or inject every 2 m from a central bus | 12 AWG (4 mm²) bus |
Worked example
5m of 60 LED/m = 300 LEDs at 5V. Realistic animations (20mA): 6.0A = 30W. Worst-case full white (60mA): 18A = 90W. With 30% headroom: pick a 5V 12A (60W) supply for animations-only, or 5V 24A if full white is ever on the menu. Inject at 0m, 2.5m, 5m.
FAQ
How many amps does a 5m WS2812B strip draw?
300 LEDs: 6A realistic (animations) / 18A worst case (full white) at 5V.
How often should I inject power?
Every 2–3 meters at 5V for 60 LED/m, always at both ends. Voltage drop is the limit — not the supply.
What fuse should I use?
~20% above worst-case draw, within 15cm of the PSU. 300 LEDs full white = 20–25A fuse (or fused sub-branches).
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