Grounding External Camper Batteries: A Step-By-Step Guide

Grounding an external battery on a camper is essential for safety and compliance. Proper grounding ensures that wiring failures do not raise the voltage to dangerous levels, preventing electrical hazards and fires. This involves connecting the negative terminal of the battery to the chassis of the vehicle, which serves as the return path for current. The specific process may vary depending on the type of camper and battery setup, and it is important to follow manufacturer guidelines and seek professional help if needed.

Grounding or earthing your camper

Types of Ground

There are two main types of ground: earth ground and chassis ground. Earth ground is a direct and physical connection to the planet Earth. In household mains systems, the third prong in a plug socket is physically connected to earth ground. Chassis ground, on the other hand, is a point in the vehicle chassis to which the negative terminal of the batteries is connected. This makes the van chassis the common return path for all return current to the battery.

AC Ground vs. DC Ground

It's important to understand the difference between AC and DC ground. In a DC system, all current should flow into the DC ground, whereas in an AC system, no current should flow into the AC ground during normal operation. This is because, in a DC system, the negative battery terminal (or "ground") is at the same electrical potential as the chassis.

Grounding in Campervans

When it comes to grounding in campervans, there are several key regulations to keep in mind, including BS 7671 (UK) and the National Electrical Code (NEC) (US). These regulations ensure that your grounding system is both safe and compliant.

For the DC system in a campervan, the negative terminal of your leisure battery and all 12V components should be grounded to the chassis. This can be done using a negative bus bar to consolidate connections, which is then wired back to the vehicle's chassis ground point.

The AC system, on the other hand, must be grounded separately to avoid cross-currents with the DC system. Use a dedicated AC ground point on the chassis for appliances like the inverter and consumer unit. It is crucial to install RCDs (Residual Current Devices) in the AC system to ensure safety, as they detect faults and disconnect power if a ground fault is detected.

Additionally, ground connections in campervans must be both permanent and accessible for inspection and maintenance. The correct colour for a dedicated ground wire is green and yellow, and the size of the wire should be appropriate for the system.

By following these guidelines, you can ensure that your campervan's electrical system is properly grounded, maintaining safety and compliance.

DC Ground vs AC Ground

Grounding or earthing your campervan is an essential step when setting up your electrical system. Proper grounding is a critical safety precaution as it provides an alternate pathway for electricity to follow if there is a fault in your system. This prevents wiring failures from raising the voltage to dangerous levels, thereby safeguarding your wires, appliances, and hopefully stopping a fire.

Now, let's delve into the differences between DC Ground and AC Ground:

DC Ground:

In a DC system, the negative terminal of your leisure battery and all 12V components should be grounded to the chassis of your campervan. This establishes the chassis as the common return path for all return current to the battery. A negative busbar is typically used as a common ground, consolidating connections for all DC components that require grounding. All DC grounds run to the negative busbar, which is then wired back to the manufacturer-assigned chassis ground point.

AC Ground:

For AC systems, such as shore power, it is crucial to ground them separately to avoid cross-currents with the DC system. This means that appliances like the inverter and consumer unit should have their own dedicated AC ground point on the chassis. The AC ground ensures that, in the event of a fault, electricity is directed away from your electrical system, protecting users and equipment.

Ground Fault Protection:

To further enhance safety, it is recommended to install RCDs (Residual Current Devices) in the UK or GFCIs (Ground Fault Circuit Interrupters) in the US for AC systems. These devices detect faults and promptly disconnect the power if a ground fault is identified. Similarly, for DC systems, fuses and circuit breakers are essential to prevent overcurrents in the event of a malfunction.

In summary, while both DC and AC grounds are vital for safety, they serve distinct purposes. The DC ground is the common return path for current in a DC system, while the AC ground provides a separate path for any faults in the AC system, ensuring the two systems remain electrically isolated.

Battery storage solutions

There are several ways to increase your battery storage capacity, especially if you are looking to be off-grid for extended periods of time. Here are some modifications (mods) that Recreational Vehicle (RV) and Truck Camper Magazine (TCM) readers have shared:

Wheel Well Area Battery Tray

This mod involves mounting a pair of identical batteries in the bed of the truck and connecting them with a large plug and cable. The auxiliary battery tray can be fabricated using angle iron and square steel tubing. It is important to ensure that the tray is securely mounted and that all connections are tightened. This mod can cost around $450 and may take 18-20 hours to complete.

Added Batteries to Basement

This modification involves upgrading the camper's electrical storage system by adding more batteries in a climate-controlled space, such as the basement. Absorbed Glass Matt (AGM) batteries are recommended for their ability to provide high discharge rates and accept high charge currents. It is important to reinforce the structure to safely support the weight of the batteries. This mod includes building a new switch panel and ensuring balanced wiring for equal load distribution during charge and discharge cycles. The total cost for this mod was $1,350 and it took 30 hours to complete.

Generator Compartment Repurposed into Battery Box

If your camper came with a built-in generator that is no longer in use, you can repurpose the generator compartment into a battery box. This involves adding a floor across the opening and building a framed basement for additional depth and volume. It is important to ensure that the framed box is securely hung and sealed to the underside of the camper floor. This mod took ten hours to complete and cost $100.

Using a Generator Compartment for Battery Storage

If you have an unused generator cabinet, you can convert it to hold additional batteries. This involves connecting the generator leads with battery terminals and drilling an access hole in the battery compartment. Reinforcing the floor pan with additional hold-down bolts is necessary to support the weight of the batteries. This mod provides increased battery storage capacity while still leaving space for other items such as a tool bag.

Battery Quick Disconnect and Upgrade

This modification involves creating a battery box that sits over the wheel well with a high-rating connector and cable. The box is designed to be easily placed and removed, making it convenient for loading and unloading the camper. The box can be extended to hold additional batteries, and external connector ports allow for future expansions such as solar or wind power sources.

Grounding the chassis

Identify the Grounding Point:

Firstly, you need to identify the grounding point on your campervan's chassis. All vehicles have pre-built ground points on the chassis. Search for your specific van model's ground points, which are usually accessible and not hidden behind cladding or insulation.

Prepare the Chassis:

If you prefer to create a new ground point, you can do so by sanding down the paint on an interior part of the chassis to expose the bare metal. Drill a hole at this point, and apply dielectric grease or Vaseline to prevent corrosion and enhance the electrical connection.

Install a Grounding Bolt:

Screw a bolt into the hole you drilled, followed by a nut and an external tooth lock washer. This assembly will serve as your new ground bolt. Ensure that the connection is secure and tight.

Connect the Grounding Cable:

Use a dedicated grounding cable, typically green and yellow, to connect the negative terminal of your leisure battery to the chassis ground point. The cable size should be appropriate, typically no smaller than one size smaller than the largest wire in the system or your battery cable.

Consolidate Connections with a Busbar:

Instead of running appliances directly to the ground point, consider using a negative busbar as a common ground for all DC components. Connect all the DC ground wires to the negative busbar, and then run a wire from the busbar to the chassis ground point.

Ensure Accessibility and Compliance:

It is important to ensure that your ground point is easily accessible for future inspections and maintenance. Additionally, comply with electrical regulations such as the BS 7671 (UK) and the National Electrical Code (NEC) (US) for grounding in campervans. These regulations provide specific guidelines for grounding connections, cable sizing, and safety measures.

By following these steps, you will effectively ground the chassis of your campervan, ensuring a safe and functional electrical system during your camping adventures.

Ground wire colours

The ground wire colours vary depending on the region and the electrical code being followed. Here are the standard ground wire colours for some commonly used electrical codes:

US National Electrical Code (NEC)

According to the NEC, the protective ground wire colour is green, green with yellow stripes, or bare copper. This code also mandates that the neutral power conductor be white or grey, and that hot (active) wires can be black, red, or blue.

IEC (International Electrotechnical Commission)

The IEC colour code for the protective ground wire is green with a yellow stripe. This code is followed by most European countries.

UK

The UK previously had its own domestic colour codes but now follows the IEC colour codes for AC branch circuits.

Canada

In Canada, the protective ground wire is green or green with yellow stripes, similar to the US NEC. The neutral wire is white, and the hot (live or active) single-phase wires are black and red.

It is important to note that working with electrical wiring can be dangerous and should be left to licensed professionals who are knowledgeable about electrical safety standards and practices.

Frequently asked questions