Campervan Electrical System Diagram & Wiring Guide (Free MKGT PDF)

Designing a safe and reliable campervan electrical system can feel overwhelming – batteries, fuses, inverters, DC-DC chargers, solar panels, cable sizes, voltage drop, and grounding all need to work together properly. To make this easier, MKGT® has created a clear high-level wiring diagram and a set of free tools to help you plan and build your system the right way.

On this page, you’ll find the official MKGT campervan wiring diagram, a downloadable PDF version, and links to our technical guides and cable size calculators for 12V, 24V and 60V systems.

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Campervan Electrical System – Wiring Diagram

The MKGT® campervan wiring diagram below shows a typical layout for a modern 12V / 24V DC system. It includes the house battery bank, main fuse and isolator, DC-DC charger (for charging from the alternator), solar MPPT controller, inverter, positive and negative busbars and the 12V fuse box supplying your interior loads.

You can download the full high-resolution PDF here:

 📄 Download Campervan Wiring Diagram (PDF)

This diagram is a simplified, high-level view of how a campervan DC system should be structured. It is not a wiring standard on its own, but a practical reference showing correct component order and safe wiring principles.

What the diagram includes

• House battery bank (AGM, GEL or LiFePO4)
• Main fuse on the positive battery cable
• Battery isolator switch for safe shutdown and maintenance
• DC-DC charger for alternator charging from the starter battery
• Solar panels connected to an MPPT charge controller
• MPPT → battery wiring with low voltage drop
• Positive and negative busbars for clean distribution
• 12V / 24V fuse box feeding interior loads
• Typical campervan loads: lights, fridge, water pump, heater, roof fans, USB sockets
• Inverter DC wiring (for 230V AC output)
• Chassis and ground connections

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Choosing the Correct Cable Size

One of the most important parts of campervan wiring is choosing the correct cable size for each circuit. Undersized cables cause excessive voltage drop, hot cables and unstable equipment. Oversized cables increase cost and can make routing more difficult.

To help with this, MKGT provides free online cable size calculators:

• 2-Core Low Voltage Cable Size Calculator (0.5–4.5 mm²)
  Ideal for interior loads such as lights, pumps, fans, USB sockets and other low/medium-current devices.
  Open 2-Core Cable Size Calculator
• Battery Cable Size Calculator (10–95 mm²)
  Designed for high-current circuits such as inverters, winches, DC-DC chargers and starter cables.
  Open Battery Cable Size Calculator

Both calculators use system voltage, current, one-way cable length and allowed voltage drop to recommend a suitable MKGT cable size, and also show estimated voltage drop in volts and percent.

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Fusing and Protection

Every positive cable leaving the battery should be protected with a correctly rated fuse mounted as close to the battery as possible (typically within 15–20 cm). The fuse is there to protect the cable – not the device – in the event of a short circuit.

Typical fuse types used in campervans:

• Blade fuses (ATO/ATC) – small 12V circuits such as lights, pumps, USB sockets.
• MIDI / MEGA fuses – inverters, DC-DC chargers, main feeds.
• ANL fuses – very high-current applications, large inverters.

Our cable calculators can also be used as a reference to select a suitable fuse rating based on the steady-state current of each circuit.

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Grounding and Negative Busbar

For a clean and reliable campervan install, it is recommended to collect all negative returns on a dedicated negative busbar and then bond this busbar to the vehicle chassis at a single, solid connection point. High-current devices such as inverters and DC-DC chargers should be wired directly back to the battery negative or negative busbar with appropriately sized cable.

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Download Additional MKGT Technical Guides (PDF)

If you want more detail, you can also download our free technical guides with diagrams, example calculations and cable tables:

• MKGT 2-Core Cable Technical Guide (PDF)
  Explains voltage drop, cable sizing for 12V / 24V / 60V and typical current ratings.
  Download 2-Core Cable Technical Guide (PDF)
• MKGT Battery Cable Technical Guide (PDF)
  Covers 10–95 mm² battery cables, current capacity, application examples and best practices.
  Download Battery Cable Technical Guide (PDF)
• MKGT Campervan Wiring Diagram (PDF)
  High-resolution version of the diagram shown above, ideal for printing or using as a planning reference.
  Download Campervan Wiring Diagram (PDF)

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Recommended MKGT Products for Campervan Wiring

To build a safe and reliable campervan electrical system, we recommend using high-quality copper cable and properly rated accessories. Below are some popular MKGT products suitable for 12V / 24V campervan installations:

Low-Voltage 2-Core Automotive Cable (Interior Circuits)

• 0.75 mm² 2-Core Flat Twin Red/Black – up to approx. 14 A
  Ideal for short runs to LED lighting, USB sockets and small loads.
• 1.5 mm² 2-Core Flat Twin Red/Black – up to approx. 21 A
  Suitable for medium loads such as fridges, fans and pumps.
• 2.5 mm² 2-Core Flat Twin Red/Black – up to approx. 29 A
  Recommended for heavier interior circuits and slightly longer cable runs.

View the full range of MKGT 2-Core Flat Automotive Cable here:
MKGT 2-Core 12V Flat Automotive Cable Collection

Battery & Inverter Cable (High-Current Circuits)

• 25 mm² High-Flex Battery / Welding Cable – approx. 170 A
  Suitable for small inverters, DC-DC chargers and short high-current runs.
• 50 mm² High-Flex Battery Cable – approx. 345 A
  Common choice for 1500–2000 W inverters and heavy-duty starter cables.
• 70 mm² High-Flex Battery Cable – approx. 485 A
  Recommended for large inverters, powerful winches and long high-current runs.

Browse the full MKGT battery and welding cable range (10–95 mm²) here:
MKGT Battery & Welding Cable Collection (10–95 mm²)

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