RCD in Your Van: Not Optional, Here's Why

Here's what most DIY builders get wrong: they install the RCD after the inverter but forget to put one on the shore power inlet. You need protection on both sources. I wire mine as: shore power inlet → RCD → changeover switch → distribution. Inverter output → second RCD → same changeover switch. The changeover switch prevents backfeeding shore power from your inverter — which is both illegal and dangerous. In the EU, van electrical installations for habitation should meet IEC 60364-7-721 (caravans) or your national equivalent. In France, NF C 15-100 section 771 applies. In Germany, DIN VDE 0100-721. In the US, ABYC E-11 covers marine/vehicle 120V systems. Most countries require 30mA trip current for personal protection.

How an RCD/GFCI Actually Protects You#

An RCD (Residual Current Device, called GFCI in the US) monitors the current flowing out on the live wire and returning on the neutral wire. In a healthy circuit, these are equal. If current leaks through your body to ground — because you touched a live wire, or a faulty appliance has an internal short to its metal case — the RCD detects the imbalance and trips in under 30 milliseconds. At 30mA trip sensitivity, the current through your body stays below the threshold for cardiac fibrillation. Without an RCD, a fault in a 230V system can deliver 100-200mA through your body — enough to kill in seconds. In a van, the risk is heightened: you're often standing on wet ground, touching metal surfaces, and working in confined spaces. Every 230V circuit in the van needs RCD protection. No exceptions.

Wiring the 230V System Correctly#

My standard 230V layout for a van: Shore power inlet (blue CEE 16A socket, IP44 rated) → 30mA RCD (Type A, which also catches DC fault currents from electronic devices) → MCB breakers (one per circuit, typically 10A or 16A) → individual circuits. For the inverter path: inverter output → separate 30mA RCD → into the same distribution board through a changeover switch or automatic transfer switch. I run two or three 230V circuits: one for general sockets (10A MCB), one for a high-power outlet for tools or cooking (16A MCB), and optionally one for the battery charger (10A MCB). Use 2.5mm² H07RN-F flexible cable for all 230V runs — it's oil-resistant, UV-resistant, and rated for mobile installations. Regular household Romex/flat twin cable is not suitable for a vehicle that vibrates and flexes.

Testing and Maintenance You Shouldn't Skip#

Every RCD has a test button. Press it monthly — the device should trip instantly. If it doesn't, replace it immediately. I also carry a socket tester with RCD trip function ($15-25 from any electrical supplier). Plug it into each 230V outlet, press the test button, and it verifies the RCD trips at the correct current. After any modifications to the 230V system, I test insulation resistance with a multimeter set to the megohm range — between live and earth, neutral and earth. Anything below 1 MOhm indicates a potential fault. For shore power connections, always use a polarity tester before plugging in at a campground — reversed polarity at a poorly wired hookup post means your neutral becomes live, and your RCD won't help because the fault current path is wrong. A simple plug-in tester ($10) catches this before it becomes dangerous. I've found reversed polarity at two campgrounds in the last year alone.