Is my RCD faulty?

The good news is: there’s most likely nothing wrong with your RCD. If the RCD (residual current device) is tripping, then it’s doing its job. Yes, it might be irritating, but the alternative could be disastrous.

Faulty appliance

The most common reason for an RCD to trip is a faulty appliance. Often, it will be an old or constantly used item. Kettles, hairdryers, and fridges are among the usual culprits.

So, you need to identify the appliance that’s causing the RCD to trip. If it’s happening rarely – just every now and then – think about what you’ve been using at those times. It could be a cake mixer or a ceiling fan, or a seldom-used heater.

If you know that a particular appliance is causing the RCD to trip, stop using that appliance.

On the other hand, the RCD might be tripping constantly. In this case, the cause might well be a frequently used item. This is how you find it:

  1. Unplug all electrical appliances.
  2. With the RCD switch off, plug in one item at a time, leaving a couple of minutes between each one.
  3. If the RCD trips, you’ve got your faulty appliance.

Faulty wiring

After testing your appliances, you may find that nothing is tripping the RCD. This could mean that there’s a fault in the electrical installation.

Damage to cables that are contained within walls and trunking can mean that there are escape routes for the electrical current. This will cause the RCD to trip. Cables can be damaged by nails and screws that are put into walls, and also by rats and mice, who chew them.

Sometimes, the RCD trips because of an accumulation of multiple ‘leaks’ – each one of which would not cause the trip by itself. The more circuits an RCD protects, the more likely this is to happen. If there’s a separate RCD for each circuit in your home, there’ll be a smaller amount of hardware for each to protect.

Test your RCD

We recommend that you test your RCD(s) every three months.

If you have only one RCD, turn on all lights, cooker, and a few other appliances. Press the button marked ‘Test’ or ‘T’, and the power in your home should switch off.

Multiple RCDs will be protecting individual circuits, so make sure that each one is correctly labelled. If you have an outdoor circuit, there’ll most likely be a separate RCD. You may also have a dedicated RCD for your lights, or for each storey of your property.

If the power does not switch off when you press the RCD test switch, give us a call on 01603 559 311.