How to Install an Inverter in a Campervan: Step-by-Step
Installing a 230V inverter in a campervan is a two-part job: the DC side (connecting the inverter to your leisure battery) and the AC side (connecting the inverter output to your 230V sockets and consumer unit). Here is the full process.
Before starting, confirm you have chosen the right size inverter. See our inverter size guide if you are still deciding.
What you need
For the DC side:
- Inverter (Victron Phoenix, Renogy, or similar pure sine wave unit)
- DC cable: 16–70mm² flexible welding cable or battery cable, length = battery-to-inverter run
- ANL fuse holder + fuse (sized to cable ampacity)
- Lugs and crimping tool (hydraulic crimper for 16mm²+)
- Heat shrink tubing
For the AC side:
- 2.5mm² 3-core flex (brown = live, blue = neutral, green/yellow = earth)
- RCD (30mA, double-pole)
- Consumer unit or fused spur
- BS1363 sockets with back boxes
- Cable clips and trunking
DC installation
Step 1: Choose location and measure cable run
Mount the inverter as close to the battery or bus bar as possible — ideally within 1–1.5m. Each extra metre of DC cable adds resistance and costs you voltage under load. Mark the mounting location (a metal surface or substantial wooden panel), ensuring 50–100mm clearance on all sides for airflow.
Measure the positive and negative cable runs from the battery terminals to the inverter terminals.
Step 2: Size DC cables
Select cable cross-section based on inverter continuous rating and run length:
| Inverter | Continuous draw (12V) | Cable (up to 1.5m) |
|---|---|---|
| Phoenix 12/800 | ~75A | 16mm² |
| Phoenix 12/1200 | ~115A | 25mm² |
| 2,000W | ~185A | 35–50mm² |
| MultiPlus 12/3000 | ~250A | 70mm² |
For runs longer than 1.5m (each way), go up one cable size to limit voltage drop.
Step 3: Crimp lugs and prepare cables
Cut cables to length. Strip 15–20mm of insulation from each end. Crimp lugs using a hydraulic crimper — do not use a hammer crimp or pliers for cables above 16mm². Seal each lug with adhesive-lined heat shrink.
Step 4: Install ANL fuse holder
Mount the ANL fuse holder on the positive cable, within 300mm of the battery positive terminal. Do not insert the fuse yet — work with the circuit de-energised. Connect the battery-side cable to the fuse holder; leave the inverter-side cable connected to the fuse holder but fuse uninserted.
Step 5: Mount and connect the inverter
Mount the inverter to its location. Connect:
- Negative DC cable: Battery negative or bus bar → inverter DC negative terminal
- Positive DC cable: Fuse holder output → inverter DC positive terminal
Torque terminals to the manufacturer's specified torque. Loose DC connections at high current heat up and can cause fires.
Step 6: Insert fuse
With all DC connections made, insert the ANL fuse into the holder. The circuit is now live up to the inverter's DC input. Verify battery voltage is present at the inverter input (should match your battery resting voltage).
AC installation
Important: The AC output of an inverter is 230V — the same as mains power. Work carefully. Ensure all AC connections are made with the inverter switched off.
Step 7: Plan your AC distribution
Decide how many 230V circuits you need (typically: sockets, lighting if you use mains lighting). The inverter output connects to an RCD, then to your consumer unit or fused spur(s).
Step 8: Wire the RCD
Connect 2.5mm² 3-core flex from the inverter's AC output terminals (live/brown, neutral/blue, earth/green-yellow) to the RCD input. Connect a second 2.5mm² cable from the RCD output to your consumer unit or socket feeds.
The RCD must be installed before any sockets — it protects all downstream circuits.
Step 9: Wire 230V sockets
Run 2.5mm² 3-core flex from the consumer unit or fused spur to each socket position. Use proper recessed back boxes. Secure cable with clips every 150–250mm. In a campervan, all wiring runs should be protected from chafing — use trunking or conduit where cable runs alongside metal edges.
Step 10: Earth connection
Connect the inverter's AC earth terminal (marked PE or with an earth symbol) to the van chassis — a clean, paint-free chassis connection. This establishes the earth reference for your 230V system. See our campervan inverter earthing guide for full details.
Commissioning
With the inverter switched off:
- Check all DC connections are tight
- Check all AC connections are tight, with no exposed conductors
- Verify RCD is wired correctly (input from inverter, output to loads)
- Switch inverter on — confirm display shows battery voltage
- Plug a lamp or phone charger into a socket — confirm 230V output
- Test the RCD by pressing the TEST button — it should trip. Press RESET to restore.
FAQ
Do I need a fuse on the negative DC cable?
The ANL fuse goes on the positive cable only. The negative does not require a separate fuse — the positive fuse protects both conductors.
Can I connect the inverter to my existing van wiring?
The inverter needs its own direct cable run to the battery or main bus bar — you cannot tap into existing 12V circuits (lighting, cigarette sockets) for the DC input.
Do I need building regulations approval to install a 230V system in a campervan?
In the UK, a campervan is a vehicle and not subject to Part P building regulations. However, any 230V work should be carried out competently and is best inspected by a qualified electrician. For insurance and safety purposes, having the installation certified is recommended.