Puesta a Tierra y Continuidad

Article 250 is one of the most-referenced articles in the code, defining the grounding electrode system, equipment grounding conductors, and bonding of metal parts so a ground fault becomes a short circuit the overcurrent device can clear.

When it applies

Article 250 governs every installation. Any time you have metal that could become energized during a fault, you are bonding it and providing a low-impedance return path so the overcurrent device can clear quickly.

Common mistakes

• Confusing grounding with bonding. Bonding ties metal together; the earth connection alone will not trip a breaker.
• Relying on the equipment grounding conductor as if it carried normal current. It is a fault path, not a neutral.
• Undersizing the equipment grounding conductor relative to the overcurrent device ahead of it.

In the field

On an industrial retrofit I traced a nuisance-trip complaint to a broken bonding jumper across a flex fitting. The fault path was running through conduit couplings with high impedance, so the breaker held long enough to energize a machine frame. I installed a proper bonding jumper, the impedance dropped, and the next fault cleared instantly. That is the whole point of the article: give current the fast, deliberate route home.