Voltage Drop 101: A Complete Guide to Outdoor Landscape Lighting

When designing or installing an outdoor landscape lighting system, one of the most overlooked but important factors is voltage drop. If you’ve ever noticed lights looking dimmer at the far end of your yard, uneven brightness, or fixtures that just don’t look right, chances are voltage drop is the culprit.

In this post, we’ll break down the basics of voltage drop, why it happens, and how to prevent it when working with low-voltage outdoor lighting systems.

What Is Voltage Drop?

Voltage drop occurs when electrical current travels through a wire and loses some of its energy due to resistance. The longer the distance and the thinner the wire, the more resistance—and the greater the drop in voltage by the time it reaches your fixtures.

For example:

• A 12V transformer sends out current.

• By the time it reaches a fixture 100 feet away, that fixture may only be getting 10.5V.

• The result? That light looks dimmer than the others closer to the transformer.

Why Voltage Drop Matters in Landscape Lighting

• Uneven Illumination: Fixtures at the end of the run may look dim compared to those near the transformer.

• Reduced Bulb Life: Some LED fixtures won’t run properly below their rated voltage.

• Energy Waste: You’ll be using more power to achieve less light output.

What Causes Voltage Drop?

1. Distance – The farther the fixtures are from the transformer, the more resistance builds up.

2. Wire Gauge – Thinner wire means higher resistance. Thicker wire (lower gauge number) reduces voltage drop.

3. Load – The total wattage of all fixtures on a run. More wattage = more current = more drop.

4. System Voltage – 12V systems are more sensitive to drop compared to 24V systems.

How to Minimize Voltage Drop

1. Use the Right Wire Gauge

   • For longer runs, use thicker wire (e.g., 10 AWG or 12 AWG instead of 14 or 16 AWG).

   • Always match wire size to distance and wattage load.

2. Shorter Runs

   • Keep wire runs under 100 feet if possible.

   • Split your runs so that no single run carries too heavy a load.

3. Balance the Load

   • Avoid connecting too many fixtures on one wire.

   • Distribute fixtures evenly across different runs.

4. Consider 24V Systems

   • A 24V system experiences less voltage drop than 12V, making it ideal for larger properties or longer wire runs. Make sure the lights are also rated to handle 24V or else it will burn out right away.

5. Hub Method Wiring

   • Instead of daisy-chaining, bring multiple wires back to a central hub near the transformer to balance voltage delivery.

Quick Example

• Transformer: 12V, 150W

• Run length: 100 feet

• Wire: 14 AWG

• Load: 80W

At the end of the run, fixtures may only be receiving about 10.8V—noticeably dimmer. Switching to 12 AWG wire or splitting the run can bring that voltage closer to 12V and restore brightness.

Voltage drop is a natural part of any low-voltage outdoor lighting system, but with the right planning, you can minimize it and keep your lights shining bright and evenly. Whether you’re a homeowner planning a DIY install or a professional designing a system, remember: distance, wire size, and load are the three keys to controlling voltage drop.