Cable Size Calculator

Cable Size Table

Why Cable Size is Important

Choosing the correct cable size for your electrical setup in a campervan, RV, or motorhome is crucial for several reasons:

1. Safety: Undersized cables can overheat and potentially cause electrical fires. Properly sized cables ensure safe operation of your electrical systems.
2. Efficiency: Proper cable sizing minimizes voltage drop, ensuring that your electrical appliances and devices receive the power they need to operate efficiently.
3. Performance: Electrical components, especially sensitive electronics, require stable voltage levels to function correctly. Adequate cable size helps maintain these levels.

Critical vs. Non-Critical Circuits

When planning your electrical system, it's essential to distinguish between critical and non-critical circuits. This distinction helps determine the acceptable voltage drop and, consequently, the appropriate cable size.

Critical Circuits (3% Voltage Drop)

Critical circuits are those that require a stable and consistent voltage to operate correctly. These circuits should not experience more than a 3% voltage drop to ensure reliable performance. Examples of critical circuits in a campervan include:

• Main Power Feeders: The primary cables supplying power from the battery to your distribution panel.
• Inverters and Chargers: Devices that convert DC power to AC power and charge your batteries, requiring precise voltage regulation.
• Navigation and Safety Lights: Essential for safe driving and visibility, especially at night.
• Sensitive Electronics: Equipment such as GPS units, communication devices, and other electronic gadgets that require stable voltage.

Non-Critical Circuits (10% Voltage Drop)

Non-critical circuits can tolerate up to a 10% voltage drop without significantly affecting performance. These circuits typically power less sensitive or non-essential equipment. Examples of non-critical circuits in a campervan include:

• General Lighting: Interior and exterior lights that are not crucial for safety or navigation.
• Appliances: Items such as fans, heaters, refrigerators, and small kitchen appliances.
• Water Pumps: Used for sinks and showers, which do not require precise voltage regulation.

How to Choose the Right Cable Size

To choose the right cable size for your application, follow these steps:

1. Determine the Current Flow: Identify the current (in amps) that your circuit will carry.
2. Identify the Circuit Type: Decide if the circuit is critical (3% voltage drop) or non-critical (10% voltage drop).
3. Measure the Cable Length: Measure the total length of the cable run, considering the round trip distance (from the power source to the device and back).
4. Consult a Cable Size Chart: Use a cable size chart, like the one provided in this guide, to find the appropriate cable size based on the current, circuit type, and cable length.

By carefully selecting the correct cable size, you can ensure the safety, efficiency, and performance of your electrical systems, whether they are critical or non-critical.