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How does the RCD work in my Caravan?


When you are at a campsite, the last thing you want is for your electricity to trip!

The kettle is boiling, kids are watching TV, food is heating in the microwave and it all comes to a halt. This article will help you to manage your electricity better and explain why your electricity may be tripping on your vacations.

Why does my caravan electricity trip?

There are two reasons why your electricity trips.

  1. You might be overloading your 230v electrics. This means you are asking one of the 230v circuits in your Caravan or Motorhome to manage too much power (Amps), usually caused by too many appliances / electrical devise on at once. This issue is managed by the MCB’s in your consumer unit.
  2. There is a circuit fault, often called an “Earth Fault” and can be caused by a faulty appliance or cable. This type of fault is serious, and can trip your caravan or motorhome, the site hook-up post or possibly a section of the site. This issue is managed by the RCD in your consumer unit. The RCD is usually a larger switch than the MCB or a different colour.

How to manage 230v Overloading

The trip switch is better known as “miniature circuit breakers” (MCBs). MCBs are like fuses in the sense that they can tolerate a small overload for a short period of time but will trip immediately with a large overload.

If you think of your house, you might have a rating of 80 or 100 amps. On a UK campsite it is usually a rating of 10 or 16 amps! With this lower amperage limit, you need to think before switching on all your appliances.

Here is a handy reference to give an approximate Amp rating for appliances that might be fitted into your caravan or motorhome:

Your 230v Appliances:

Fridge = 0.4 – 1.2A
Cooker Hob = 3.4A
Charger = 0.1 – 1.0A
Water Heater = 3.4A
TRUMA Combi E = 8.0A
ALDE = 3.0 – 13.0A

Please check your handbook to confirm the specific details for the appliances fitted to your vehicle.

Managing a situation where your RCD trips:

If your RCD trips, this is the signal for a potentially dangerous situation.

Remove everyone from your caravan or motorhome, remove the hook-up cable from the site post.

Contact the warden on site and seek professional advice.

How does an RCD system work?

You will have an RCD in your consumer unit & Earth cables throughout your vehicle.

The 230v flex in your vehicle has three core wires:

  1. Brown / Live Wire = This carries the 230v current to an appliance.
  2. Blue / Neutral Wire = Carries the current back from the appliance.
  3. Yellow & Green / Earth Bonding = Your Protection!

If a live wire contacts an appliance or part, the part can become “live”, potentially causing an electric shock. The Earth system enables the live feed to pass to Earth via the Yellow & Green wiring. When this happens the RCD will trip, indicating a serious fault.

In normal operation the current in the live and neutral wires should balance. The current level (measured in Amps) that flows down the live wire should return via the neutral wire from an appliance.

If current leaks away (ie goes to Earth), the RCD is triggered due to current imbalance. It is that imbalance sensed by the RCD, which then trips the supply, saving you from electrocution.

MCB Overload – Top Tips:

Before going away, look in your consumer box, identify your MCB’s.

Manage your 230v power consumption.

Items that produce heat use a lot more power! Think microwave, hairdryers, kettle…

Think 1000 watts equates to just over four amps at 230 volts!

RCD Trip – Top Tips:

Before going away, look in your consumer box, identify your RCD.

Connect to a 230v hook-up point, check that the test button next to your RCD works, and cuts the power.

A “live” wire fault will trip your RCD which can save you from an electric shock. For the RCD to do its job, the Earth cable system MUST be in an operational condition. This will be checked in your annual service or an EICR test (see more down below).

If you cannot identify and isolate the cause of an earth fault, do not continue to use the 230v hook-up.

The most important piece of advice here is to get your caravan or motorhome electrics checked by a qualified electrician.

Making sure your electrics are safe:

National Caravan Council (NCC), and The Electrical Safety Council recommend Caravans, Motorhomes and Campervans should undergo an EICR (Electrical Installation Condition Report) every three years. As an Approved Workshop, Bristol Caravans are qualified to complete this work for you. We suggest you book your EICR alongside your service ensuring ultimate safety before your holidays!

If you have a question, problem, or would like more information on EICR please give us a call. Contact us on 01454 612893 to book your EICR now!