How to Install an Inverter in a Van or RV (Step by Step)
Installing an inverter is one of the bigger wiring jobs in a van build — not because it's complicated, but because it carries the highest currents of any circuit in the system and needs to be done right. Here's the full process.
For choosing which inverter to buy, see best inverter for RV & van builds and what size inverter do I need?. For how to wire 120V outlets from the inverter, see how to wire an inverter in a van.
What you need
- Pure sine wave inverter (sized for your loads)
- Heavy gauge cable (see sizing below)
- ANL fuse holder + fuse (sized to the inverter's input current)
- Ring terminals — large, correctly sized for your cable gauge
- Hydraulic or heavy-duty cable crimper
- Heat shrink tubing
- Main battery disconnect switch (recommended)
- 120V outlet boxes and Romex/THHN wire for the AC side
Step 1: Choose the location
Mount the inverter as close to the battery as possible — ideally within 3 feet. Every foot of cable at inverter-level currents costs you in cable cost, weight, and voltage drop.
Location requirements:
- Ventilated — inverters generate heat under load; don't mount in a sealed box
- Accessible — you'll want to reach the on/off switch and indicator lights
- Away from flammables — keep clear of foam insulation, fabric, or anything combustible
- Stable — mounted solidly; vibration can loosen terminals over time
Step 2: Size your cables
Inverter cables carry the highest current in a 12V system:
| Inverter wattage | Max DC amps | Max cable run | Minimum cable |
|---|---|---|---|
| 1,000W | ~90A | 3 ft | 4 AWG |
| 1,000W | ~90A | 6 ft | 2 AWG |
| 2,000W | ~175A | 3 ft | 2/0 AWG |
| 2,000W | ~175A | 6 ft | 4/0 AWG |
| 3,000W | ~265A | 3 ft | 4/0 AWG |
Use fine-stranded welding cable rather than stiff battery cable — it's much easier to route through a van build without cracking the insulation.
Use the same heavy gauge for both the positive and negative cables.
Step 3: Fuse at the battery — within 12 inches
The inverter fuse must be within 12 inches of the battery positive terminal. A short circuit on an unfused cable at 175A will cause a fire before anything else fails.
ANL fuse sizing: 125% of the inverter's max input current.
- 1,000W inverter (~90A max): 100–125A ANL fuse
- 2,000W inverter (~175A max): 200–250A ANL fuse
- 3,000W inverter (~265A max): 300A+ ANL fuse
Mount the ANL fuse holder on the positive cable between the battery terminal and the inverter.
This fuse is your fire protection
The most common van electrical fire cause is unfused or under-fused large cable. The inverter cable carries more current than any other wire in the system. Don't skip the ANL fuse or mount it far from the battery.
Step 4: Add a disconnect switch (recommended)
A battery disconnect switch on the inverter positive cable lets you fully isolate the inverter when not in use, eliminating standby draw and providing a safety cutoff. Blue Sea Systems makes excellent rotary disconnect switches rated for high current.
Mount it in an accessible location — near the inverter, or at a convenient panel location.
Step 5: Connect the DC side
- Connect the negative cable from the inverter to the main negative bus bar (not directly to the battery negative terminal — route all negatives through the bus bar)
- Run the positive cable from the battery positive, through the ANL fuse holder, to the inverter positive terminal
- Torque the terminal bolts to spec — inverter terminal connections that work loose under vibration are a fire risk
Step 6: Wire the 120V AC output
The AC side carries 120V — treat it with the same respect as household wiring.
Option 1: Single outlet or outlet box — run standard 12 AWG Romex or 12 AWG THHN wire from the inverter AC output to a weatherproof outlet box. This is the simplest approach for a single outlet near the inverter.
Option 2: Mini breaker panel — for multiple outlets in different locations, run the inverter output to a small AC breaker panel (Siemens, Square D — 4 or 6 space). Each circuit gets its own 15A or 20A breaker and runs to outlets in different areas of the van. This is the right approach for a build with outlets in multiple locations.
For the full 120V outlet wiring guide: how to wire 120V outlets from an inverter.
GFCI protection: Install GFCI outlets or a GFCI breaker on any circuit in a wet area — kitchen, bathroom, outdoors. Required by NEC for safety; standard for any build.
Step 7: Ground the inverter chassis
The inverter chassis (the metal body) must be connected to the system's main negative bus bar or battery negative with a short ground wire. Without this, the chassis can become energized in a fault — a shock hazard.
Step 8: Test
Before energizing the system:
- Confirm all connections are tight
- Confirm the ANL fuse is installed
- Confirm the disconnect switch is off
- Turn the disconnect on, then the inverter on
- Check the display — it should show battery voltage (~12.8V for a resting LiFePO4 battery)
- Plug in a small load (phone charger or lamp) and confirm it works
- Check for any unusual heat at connections after 10–15 minutes of operation
Standby power draw
Most inverters draw 5–15W in standby (inverter on, no load). For a build where you leave the inverter on 24/7, that's 120–360Wh/day of wasted power. Use the disconnect switch or the inverter's remote on/off to turn it off when you're not using AC power.