Low Voltage Wire Gauge & Length Calculator
DC & AC Power Calculator (1V–50V, 0.1A–50A) – Supports 30AWG to 12AWG Wire, Up to 150 Feet
Demystifying Wire Gauge Selection:
Simple Guide to Sizing Wires for Low Voltage Projects
Practical Wire Gauge Examples:
Real-Life Calculator Demonstrations
Terms and Notes
Voltage
:
This calculator supports both AC and DC circuits. If your power source is a battery, consider using its nominal voltage for calculations. For example, if using a 12V DC car battery, consider using 12V as the nominal voltage. Keep in mind that a car battery reading below 12V typically indicates a low charge (around 25%) or a potentially faulty battery. Therefore, 12V is a reasonable calculation value.
When a 12V DC car battery is running (engine on and alternator charging), the voltage should typically be between 13.7V and 14.7V.
A healthy 12V car battery when the engine is not running should typically read between 12.6V and 12.8V when fully charged.
Here’s a general guide:
- 12.6V – 12.8V → Fully charged
- 12.4V – 12.5V → ~75% charged
- 12.2V – 12.3V → ~50% charged
- 12.0V – 12.1V → ~25% charged
- Below 11.9V → Likely discharged or bad battery
Using a lower or nominal voltage, such as 12V instead of 13V-14V, in calculations, result in a more conservative estimate. According to industry standards, the wire should be able to handle worst-case scenarios. If the system operates at a higher voltage, the voltage drop is reduced, allowing for potentially longer wire runs. As long as the amp load remains below the wire’s maximum amp rating, the selected wire gauge should fall within industry standards for a safe and acceptable operating range.
End Voltage
:
End voltage is the amount of voltage that reaches the device after traveling through the wire. The longer the wire, the more resistance it has, which causes a voltage drop. This means the voltage at the start of the wire is higher than at the end. If the voltage drops too much, the device may not work properly or may not have enough volts to power up.
Max Length One-Way
:
The distance from the power source positive terminal (+, hot, live, PWR) to the load (device), excluding the return path through the negative terminal (-, ground, common, or neutral). The total distance, including both the positive and negative paths, is referred to as the round-trip length, which is twice the one-way distance.
Amp Rating
:
The maximum amount of electrical current (in amperes) that a specific wire gauge (measured in American Wire Gauge, or AWG) can safely carry without overheating.
80% Rule
:
Refers to the recommendation that a circuit should not be loaded to more than 80% of its maximum rated capacity.
Fusing Current
:
The minimum current (amps) that causes a fuse to blow.
Preece ≈10s
:
The wire can withstand short durations of increased amperage (up to the Preece value) without melting or degrading before the fuse blows, which can help improve safety, and reduce fire hazards.
