Caravans run on two separate electrical systems that work together: 12V DC for lighting, water pumps, and control circuits, plus 240V AC from mains hookup for sockets, heating, and high-power appliances. Getting the interaction between these two systems right is the key to safe, reliable caravan electrics.

What you'll learn: How to design a complete 12V 240V caravan wiring diagram, the role of each component in a dual voltage system, proper hookup panel wiring, RCD and MCB protection requirements, and how your converter/charger bridges both systems.

How Caravan Electrical Systems Differ from RVs and Boats

If you've read our RV electrical system design guide or boat wiring guide, you'll notice caravan systems have distinct characteristics:

240V AC is a primary power source - Unlike RVs that often rely heavily on 12V DC with occasional inverter use, caravans are designed around mains hookup. Most caravan parks provide 240V AC supply as standard.

Converter/charger is always present - The 240V supply feeds a converter that provides 12V DC power and charges the leisure battery simultaneously.

UK/European wiring standards apply - Caravan electrical installations must comply with BS 7671 (IET Wiring Regulations) and the specific requirements of BS EN 1648 for leisure vehicle installations.

Hookup panel is the central connection point - The mains inlet, RCD, and MCBs are housed in a dedicated hookup panel, not distributed throughout the vehicle like residential wiring.

The 240V AC Side: Mains Hookup System

Hookup Panel Components

The 240V system starts at the mains inlet and flows through these components:

Mains inlet socket - External weatherproof socket (typically blue CEE connector) where the hookup cable connects. This must be positioned so water drains away from the connection.

RCD (Residual Current Device) - The most critical safety component. The RCD trips within milliseconds if it detects current leaking to earth, protecting against electric shock. Caravans require a 30mA RCD as the first protective device after the inlet.

MCBs (Miniature Circuit Breakers) - Individual circuit protection for each 240V circuit. Typical caravan MCB ratings:

Circuit	MCB Rating	Cable Size
Sockets	16A	2.5mm²
Water heater	16A	2.5mm²
Heating (if electric)	10A-16A	1.5-2.5mm²
Converter/charger	10A	1.5mm²
Lighting (if 240V)	6A	1.0mm²

Earth bonding - All exposed metal parts of the caravan must be bonded to the earth terminal in the hookup panel. This includes chassis, metal sinks, taps, and any metal casings.

240V Circuit Wiring Rules

Cable specification: Use only flexible cable rated for the application. Three-core cable (live, neutral, earth) for all fixed wiring. All cables must be adequately supported and protected from damage.

Socket outlets: Must be shuttered type and positioned where they won't be exposed to water splashes. Keep sockets at least 300mm from the floor.

Isolation: The mains inlet must disconnect all live conductors (both line and neutral) when unplugged. Never wire the neutral as a switched conductor.

The 12V DC Side: Battery and Low Voltage System

12V System Components

Leisure battery - The heart of your 12V system. LiFePO4 batteries are the best choice for caravans due to their light weight and deep discharge capability. A 100-200Ah battery suits most touring caravans.

Converter/charger - Bridges the 240V and 12V systems. When connected to mains, it:

Powers all 12V circuits directly
Charges the leisure battery with a multi-stage charging profile
Automatically switches between mains-powered and battery-powered operation

12V distribution panel - Fused distribution for all DC circuits, typically blade fuses in a central fuse box:

Circuit	Fuse Rating	Wire Gauge
Interior lights	5-10A	1.0-1.5mm²
Water pump	10A	1.5mm²
12V sockets	10-15A	1.5-2.5mm²
Control panel	5A	1.0mm²
Fridge (12V element)	15-20A	2.5mm²
Awning light	5A	1.0mm²
Mover (if fitted)	30A+	6.0mm²+

For detailed wire sizing, see our wire gauge sizing guide.

Battery Charging Sources

A well-designed caravan has multiple ways to charge the leisure battery:

Mains hookup (via converter/charger) - Primary charging when on site. A quality multi-stage charger prevents overcharging and extends battery life.

Tow vehicle alternator - Charges while driving. Modern vehicles with smart alternators need a DC-DC charger rather than a simple split-charge relay. This keeps the battery topped up during travel.

Solar panels - Ideal for maintaining charge during extended stays. Even a modest 100-200W panel setup keeps a caravan battery healthy. See our solar panel sizing guide for detailed calculations.

Designing Your 12V 240V Caravan Wiring Diagram

Step 1: Map Your Electrical Loads

List every electrical device in your caravan and note whether it runs on 240V AC, 12V DC, or both:

12V DC loads (typical):

LED ceiling lights (2-5W each)
Water pump (30-50W)
12V sockets for USB charging
Control panel and status lights
Awning light
Toilet flush pump
Fridge 12V element (for travel)

240V AC loads (typical):

Mains sockets (for kettles, phone chargers, hair dryers)
Water heater element
Space heater (if electric)
Fridge 240V element (when on hookup)
Converter/charger (feeds the 12V system)

Step 2: Plan the 240V Distribution

Start from the mains inlet and work through the protection chain:

Mains inlet receives hookup cable
RCD provides earth leakage protection for the entire 240V system
MCBs protect individual circuits
Circuits run to sockets, water heater, and converter/charger

Key safety point: The converter/charger must be on its own MCB circuit. If the charger trips its breaker, your 12V system switches seamlessly to battery power.

Step 3: Plan the 12V Distribution

From the leisure battery or converter output:

Main fuse at the battery positive terminal
Bus bar or distribution panel for positive connections
Individual fused circuits to each 12V load
Negative bus bar for all return connections
Single ground point back to battery negative

For proper fuse sizing and placement, every positive wire must be fused at its power source.

Step 4: Design the Changeover System

The converter/charger handles the transition between mains power and battery power:

On hookup: Converter supplies 12V DC to all circuits and charges the leisure battery. 240V circuits are live.

Off hookup: Leisure battery powers all 12V circuits. 240V circuits are dead (no power).

Important: Never attempt to back-feed 240V into the system using an inverter connected to the mains inlet. If you want 240V from battery power, install an inverter on the 12V side with its own dedicated 240V circuit, completely isolated from the mains hookup wiring.

Step 5: Document Everything in VoltPlan

A complete 12V 240V caravan wiring diagram should show:

Both voltage systems clearly distinguished
All protection devices (RCD, MCBs, fuses) with their ratings
Cable sizes for every run
The converter/charger as the bridge between systems
Battery charging sources and their connections
Earth bonding connections

Open VoltPlan and start designing your caravan wiring diagram - it's free for personal use. Use our pre-built templates to get a head start, then customise for your specific caravan layout.

Common Caravan Wiring Mistakes

Skipping the RCD - A 30mA RCD is mandatory for caravan installations. It's the single most important safety device in your 240V system. Without it, a fault could be lethal.

Wrong cable type for 240V - Domestic cable (T&E / twin and earth) is not suitable for caravan use. Use flexible cable rated for mobile installations.

No isolation between mains and inverter circuits - If you add an inverter, its 240V output must never connect to the mains hookup wiring. A fault could energise the hookup cable and endanger others on the park.

Undersized cable for the mover - Caravan movers draw 30A or more. Undersized cable overheats and can cause fires. Always use the cable size specified by the mover manufacturer.

Poor earth bonding - Every piece of exposed metalwork must be bonded. A loose or missing earth bond means the RCD may not trip when needed.

No diagram documentation - Caravan electrics are complex enough that working from memory is a recipe for mistakes. A clear wiring diagram makes future maintenance and fault-finding far easier.

Safety First: When to Call a Professional

While this guide covers the principles of caravan electrical design, 240V mains wiring is potentially lethal. If you're not confident working with mains electricity:

Have a qualified electrician inspect your work before energising the system
NCC Approved Workshop scheme provides certified caravan electrical installers
Annual habitation checks should include electrical testing

A professional sign-off gives peace of mind and may be required for insurance purposes.

Next Steps

Ready to design your caravan's electrical system?

List all your 12V and 240V loads
Choose your leisure battery - LiFePO4 is recommended for new installations
Plan your charging sources (hookup charger + solar + alternator)
Start your caravan wiring diagram in VoltPlan - free for personal use

A properly designed dual voltage system gives you the best of both worlds: reliable 12V power for off-grid freedom and full mains convenience when connected to hookup. Take the time to plan it right, and your caravan electrics will be safe, reliable, and easy to maintain for years of touring.

12V 240V Caravan Wiring Diagram: Dual Voltage System Guide