Caída de tensión en tira LED: 12V vs 24V, NEC 411/725 y calibre
Calcula tiras LED de 12V y 24V con resistencia de cobre, NEC 411, NEC 725, IEC SELV/PELV y ejemplos reales.
Una tira LED es de baja tensión, pero en 12V el margen es pequeño. Si el extremo se ve tenue o cambia de color, revise primero la caída en cable, conectores y cobre de la tira.
Resumen
- 12V systems have a small voltage budget; 24V reduces current for the same watts.
- Calculate each branch from watts, volts, wire size, and one-way route length.
- NEC 411 and NEC 725 guide installation; voltage drop still needs math.
- Parallel home runs or two-end feeds improve long visual runs.
Caída de tensión en tira LED: 12V vs 24V, NEC 411/725 y calibre
Una tira LED es un circuito flexible con diodos emisores de luz. La caída de tensión es el voltaje perdido en la resistencia. Un circuito Class 2 viene de una fuente limitada.
Revise NEC 411, NEC 725 y NEC 110.3(B); en proyectos IEC, confirme SELV/PELV y las reglas locales de instalación.
En coves, muebles y letreros largos conviene dividir en ramales paralelos, alimentar por ambos extremos o acercar el driver.
Class 2 limita la fuente, pero no elimina la resistencia de cables, clips ni bornes del dimmer.
Comparación de tiras LED 12V y 24V
| System | Load | Example drop | Best use | Check |
|---|---|---|---|---|
| 12V single feed | 48W / 4A | 1.28V on 18 AWG, 25 ft | Short cabinets | NEC 411/725 |
| 24V single feed | 48W / 2A | 0.64V on same wire | Longer coves | Driver listing |
| Two-end feed | Current splits | Lower far-end drop | Continuous runs | Polarity and listing |
| Parallel home runs | Smaller branches | About 1% in example sign | Signs and retail | Terminal ratings |
| Daisy chain | Rising current path | Often high | Only short links | Connector amp rating |
Examples
Una tira de 48W a 12V consume 4A. Con 18 AWG cobre y 25 ft de ida, cae cerca de 1,28V, o 10,6%.
La misma carga de 48W a 24V consume 2A. En el mismo cable cae unos 0,64V, o 2,7%.
“For long LED runs, split current paths before blaming the driver. Four 30W branches usually beat one 120W daisy chain.”
— Hommer Zhao, Technical Director
Preguntas frecuentes
12V LED strip distance?
A 48W load at 12V draws 4A; on 18 AWG at 25 ft one way, drop is about 1.28V or 10.6%.
Why choose 24V?
For the same 48W, 24V uses 2A, so the same copper path drops about half the voltage percentage.
Which code sections matter?
Check NEC 411 for low-voltage lighting, NEC 725 for Class 2 circuits, and NEC 110.3(B) for listed instructions.
Can both ends be fed?
Yes when the strip manufacturer permits it and polarity is correct; it reduces current per path on long runs.
What target is reasonable?
Use 3% to 5% as a starting point, then tighten it if color or brightness uniformity is critical.
Antes de tender cable y cortar la tira, compare tensión, watts, calibre y distancia real en la calculadora.
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