In your motorhome's 230V consumer unit (the "mains power" side of things) there are two devices that act as your safety guardians: the RCD (residual current device) and the circuit breaker. They work silently, but they can prevent a fatal shock or a fire. Knowing them and checking them is part of travelling safely. Here's what each one does, without the jargon.
Your camper's 230V consumer unit
When you plug into the campsite's mains supply (230V), that current enters a small electrical panel before being distributed to the camper's sockets (see the electrical panel). In that panel you'll find the RCD and the circuit breaker, just as in your house.
The RCD: protects your life
The residual current device (RCD) monitors that all the current going in returns the way it should. If it detects a leak (for example, because current is escaping through a person who has touched something faulty), it cuts the power in milliseconds. It's what prevents electrocution. Its job is to protect you.
The circuit breaker (MCB): protects the electrical system
The miniature circuit breaker (MCB) protects the cables and wiring against overloads (too many appliances at once) and short circuits: it trips, cutting the power before the cables overheat and could cause a fire. Its job is to protect the system.
Why they matter and how to check them
- They're not optional: a 230V electrical system without these protections is dangerous.
- Test the RCD: it has a test button (T) which, when connected to the mains, should trip it; test it occasionally to confirm it's working.
- If they trip, there's a reason: don't bypass or disable them; find the cause (a faulty appliance, too much load, damp).
- If in doubt, call a professional: the 230V side is the most dangerous; have someone who knows what they're doing check it.
And the 12V side
The 12V (battery) side is protected with fuses, which serve a similar function to the circuit breaker against short circuits and overloads (see fuses and protection). Both worlds (230V and 12V) need to be properly protected.
In summary
The RCD protects your life (cutting power in the event of a leak to prevent electrocution) and the circuit breaker protects the electrical system (cutting power in the event of overloads and short circuits to prevent fires); both are essential in the 230V consumer unit. The step to take today: find your camper's panel, press the RCD's test button to confirm it trips, and if something trips frequently, find the cause without ever disabling the protections. Combine it with the electrical panel.