Low-Voltage Lighting

Article 411 covers lighting systems that run at 30 volts or less, supplied by a listed transformer or power supply from a normal branch circuit. Think landscape lighting, under-cabinet strips, and exposed low-voltage track and cable systems. Low voltage reduces shock risk, so some of these systems use bare or lightly insulated conductors.

The catch is current and power: even at low voltage, a shorted or overloaded conductor can get hot enough to be a fire hazard, so the article limits secondary power, requires listed supplies with built-in protection, and sets rules for burial, wet locations and keeping exposed conductors away from ignitable material.

When it applies

This covers lighting fed through a power supply or transformer down to 30 volts or less — landscape path lights, cove and under-cabinet strips, some track and display systems. The low voltage feels forgiving, but the article still governs the supply, wiring methods and how you protect the secondary conductors.

Common mistakes

• Treating the secondary side as unlimited — those conductors still need overcurrent and sizing appropriate to the load and distance.
• Undersizing the run and living with dim, flickering fixtures from voltage drop at the far end.
• Using a transformer or driver not listed for the wet or outdoor location it sits in.

In the field

On a landscape lighting job I always account for voltage drop across the whole loop before I set the fixtures. Low voltage does not mean low physics; a long thin run leaves the last light half as bright as the first unless you size the wire for the distance.