Cordones y Cables Flexibles

El Artículo 400 cubre los cordones y cables flexibles que conectan equipo móvil — los tipos SO, SJO, SPT y similares, con una gran tabla de construcciones, aislamientos y ampacidades. Te dice qué cordón está clasificado para uso rudo, lugares húmedos o servicio extra rudo.

Su mensaje más importante es lo que el cordón NO puede hacer: no puede sustituir el cableado fijo de una estructura, no puede pasar por paredes, techos o pisos, y no puede ocultarse ni fijarse a superficies del edificio como cableado permanente. El cordón es para flexibilidad y desconexión, no para ahorrarse el costo de un circuito adecuado.

When it applies

Article 400 covers flexible cords and cables like SO, SJ, and SPT. The core idea is that flexible cord is for things that move, vibrate, or need frequent disconnection, not as a substitute for fixed building wiring.

Common mistakes

• Using cord as permanent wiring, running it through walls or ceilings in place of a raceway. That is a classic violation.
• Sizing the cord for the load but ignoring the ampacity reduction when conductors are bundled or the cord is long.
• Leaving a cord unprotected where it passes through an opening and letting the edge chafe the jacket.

In the field

In a plant I found extension cord stapled along a wall feeding a permanently mounted machine, run right through a knockout. That cord was doing a raceway's job and the jacket was already worn at the metal edge. I pulled it out and ran proper conduit to the machine. Flexible cord earns its place where equipment actually flexes or gets unplugged; bolt something down and it deserves real wiring.