For a permanent van build, the answer is almost always: hardwire the inverter. Here's why, and the cases where a plug-in approach works.
Hardwired inverter
How it works: Heavy gauge cable runs directly from battery positive (through a large fuse/breaker) and battery negative to the inverter's DC terminals. The inverter is mounted permanently in the van.
Advantages:
- Lower resistance = less voltage drop under load = more efficient operation
- Can support large inverters (1,000W, 2,000W, 3,000W+) — plug connections can't safely handle the current
- Cleaner installation, secured mounting
- Easier to integrate with a master switch or remote panel
Cable sizing for hardwired installation:
| Inverter size | Full load current | Minimum cable (3 ft run) | Minimum cable (6 ft run) |
|---|---|---|---|
| 1,000W | ~90A | 1/0 AWG | 2/0 AWG |
| 2,000W | ~175A | 2/0 AWG | 4/0 AWG |
| 3,000W | ~260A | 4/0 AWG | 4/0 AWG |
Always fuse within 18 inches of the battery positive terminal. Fuse rating should be 125% of the inverter's maximum DC input current.
Plug-in inverter
How it works: The inverter connects via a 12V socket (cigarette lighter), Anderson connector, or SAE connector rather than being wired directly to the battery.
12V socket (cigarette lighter): Most are fused at 10–20A, limiting you to 100–200W. Fine for a small inverter charging a laptop or phone while driving, but not for any serious van electrical work.
Anderson SB50 or SB175 connector: A heavy-duty connector rated for 50A or 175A. Some van builders use these for a portable inverter that can be moved between vehicles. Works well for up to 500W (SB50) or ~2,000W (SB175). Adds a small voltage drop at the connection.
Anderson PowerPole: Smaller connectors for lower current — not suitable for inverters above ~200W.
When plug-in makes sense
- Portable inverter for on-the-go use: A small (150–400W) inverter that you use occasionally while driving, then store when not needed. A 12V socket or SB50 is fine.
- Temporary setup or van conversion in progress: Plug-in while you build out the full system.
- Dual-vehicle use: Anderson connector allows the same inverter to move between a van and a tow vehicle without rewiring.
When you must hardwire
- Any inverter over 500W
- Any inverter that will be used regularly or full-time
- Any inverter integrated with shore power (inverter/charger with ATS)
- Any inverter powering a fixed induction cooktop, microwave, or AC outlet panel
Related
Frequently Asked Questions
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Roam Wired
Roam Wired turns campervan research into practical plans. We publish transparent guidance, a free electrical design tool and marketplace resources for UK and US van builders.
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