What Does “Low Voltage Size” Mean? A Simple Guide to Low Voltage Wiring
If you’ve ever worked with lighting systems, security cameras, or smart home setups, you’ve probably come across the term “low voltage size.” But what does it actually mean?
In electrical systems, low voltage size refers to the thickness (or gauge) of the wire used to carry low-voltage electrical current. Choosing the correct size is critical for ensuring your system runs safely, efficiently, and without voltage drop problems.
Let’s break down what this means and how to pick the right wire for your project. Our low voltage installation experts in San Jose ensure each project uses the correct wire size to maintain safety and efficiency.
Understanding Low Voltage
Low voltage typically means any system operating below 50 volts (V). Common examples include:
- Doorbells and thermostats (24V)
- Landscape lighting (12V)
- Security cameras and alarm systems (12V–24V DC)
- Smart home controls and sensors
- Ethernet and communication cables
These systems use less power than standard 120V household wiring, which makes them safer to handle — but they still require proper wire sizing to function correctly.
What “Size” Means in Electrical Terms
When we talk about “wire size,” we’re really talking about wire gauge, measured by the American Wire Gauge (AWG) standard. The smaller the AWG number, the thicker the wire.
For example:
- 12 AWG wire is thicker than 16 AWG wire
- Thicker wires can carry more current over longer distances with less voltage loss
So when someone asks about “low voltage size,” they’re referring to the wire gauge appropriate for the voltage, amperage, and distance of their circuit.
Why Wire Size Matters in Low Voltage Systems
Even though low voltage wiring carries less current, using the wrong wire size can still cause issues.
Here’s why proper sizing is important:
- Prevents voltage drop – If the wire is too thin or too long, the voltage reaching your device will be lower than expected.
- Improves efficiency – Correct wire size ensures consistent performance across your devices.
- Reduces heat – Thicker wires handle more current safely without overheating.
- Increases lifespan – Properly sized wires reduce stress on transformers, power supplies, and connected devices.
How to Choose the Right Low Voltage Wire Size
To select the correct low voltage cable size, consider three main factors:
- Voltage of the system – Common low voltage systems are 12V, 24V, or 48V.
- Current (amperage) – How much power your devices draw.
- Distance of the run – The longer the wire, the more resistance and voltage drop you’ll have.
A general rule:
- For short runs (<50 ft), 18 AWG is often enough.
- For medium runs (50–100 ft), use 16 AWG.
- For long runs (>100 ft), choose 14 AWG or thicker.
Always check your device manufacturer’s specifications or use a voltage drop calculator to find the ideal gauge for your setup. Understanding wire polarity is just as important as size. Learn which wire is positive in a low voltage circuit to avoid common installation mistakes.
Common Wire Sizes for Low Voltage Applications
| Application | Typical Voltage | Recommended Wire Size |
|---|---|---|
| Landscape lighting | 12V | 12–16 AWG |
| Security cameras | 12V–24V DC | 18–20 AWG |
| Doorbells | 24V | 20–22 AWG |
| Thermostats | 24V | 18 AWG |
| Smart home sensors | 12V–24V DC | 18–22 AWG |
| Low voltage LED strips | 12V | 14–18 AWG |
These are general recommendations — always verify with your installer or system manual for the safest results.
Avoiding Voltage Drop
One of the biggest challenges in low voltage wiring is voltage drop — when voltage decreases along the wire due to resistance.
To reduce voltage drop:
- Use thicker (lower AWG) wire for long runs
- Keep wire lengths as short as possible
- Split large loads across multiple runs
- Use a higher voltage system (for example, 24V instead of 12V) when feasible
These small adjustments help maintain consistent brightness, power, and reliability across your devices.
Low Voltage Systems in California
If you’re installing or upgrading low voltage wiring in California, remember that it’s regulated under low voltage (C-7) electrical licensing. Contractors must follow the California Electrical Code and NEC (National Electrical Code) for safety and compliance.
Certified low voltage professionals can design and install systems for:
- CCTV and security
- Access control
- Audio/visual networks
- Data cabling (Cat6, fiber, etc.)
- Smart home automation
Working with a licensed low voltage installer ensures your project is safe, efficient, and code-compliant. Knowing wire size helps you understand the broader purpose of low voltage wiring, especially when designing safe, energy-efficient systems.
Key Takeaways
- “Low voltage size” means the wire gauge used for low-voltage systems.
- The smaller the AWG number, the thicker the wire.
- Choose wire size based on voltage, current, and distance.
- Proper sizing prevents voltage drop, improves efficiency, and extends system life.
- Always follow local codes and standards when installing low voltage wiring.