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Residual Current Devices (RCD's)

· Electrician,Electrical,Electrician Cork

What is an RCD?

An RCD (Residual Current Device) is a safety device designed to protect people from getting fatal electric shocks from contact with live electricity. RCD’s also offer some level of protection from electrical fires caused by earth faults.


An example of an earth fault could be hitting a live wire when inserting a screw into a wall, or a faulty appliance overheating causing the electric current to flow to earth.


What does an RCD do?

An RCD switches off electricity automatically if there is a fault detected.

How does it work?

A residual current device will constantly monitor an electric current flowing through one or more electrical circuits which it is protecting. If the device senses electricity flowing in an unintended path such as to earth through an overheating appliance, the RCD will switch off the circuit reducing the risk of electric shock and potential fires.

What are the main types of RCD?

RCDs are there to help prevent electric shock in high risk areas such as kitchens, gardens and bathrooms, as such there are several different types which you should be aware of.

Fixed RCDs

Fixed RCD’s are installed in Fuse box’s and can monitor individual or groups circuits.

A fixed RCD provides the most protection as it monitors and protects all the associated wiring and sockets on a circuit, including appliances which are connected.

Socket-Outlet RCDs

Socket-Outlet RCD’S are sockets which have a residual current device built into them. A Socket- Outlet RCD only protects the person in contact with equipment or lead which is plugged into the said socket-outlet RCD.

Portable RCDs

Portable RCD’s plug into standard sockets. Users then plug various appliances into the portable RCD. They are useful when there are no fixed or socket-outlet RCDs available. As with the Socket Outlet RCD’s, portable RCD’s only protects the person in contact with equipment or lead which is plugged into the said portable RCD.

How much does RCD protection cost?

Portable RCD’s can be purchased for roughly €11.00

Fixed RCD’s will cost more than this and price will vary depending on the job and what is required.

Can I check myself if I have fixed RCD protection?

Yes, if you go to your fuse box and look for a push button with either “T” or “Test” This is part of the RCD, you can also reference the picture accompanying this post.

Final Notes

By having fixed RCD protection in your home, you are reducing the risk of electric shock and electrical fires.

Although RCD protection reduces your risk of electric shock and electrical fires, it is by no means a substitute to being vigilant.

Inspections: We recommend you have your wiring inspected at least every 8 - 10 years to ensure your home is electric safe.

If at any point you find a fault with your wiring or appliances, stop using whatever it is showing the signs of a fault immediately and contact either a registered electrician or

Testing: You should test all RCDs once every quarter both fixed and portable.

Manufacturers of portable RCDs recommend they are tested with every use.

Failed Test:  If one of your RCD’s does not switch off your electricity, then contact either a registered electrician or If it is a portable RCD get a new one.

If at you find a fault with your wiring or any of your appliances, stop using whatever it is, contact a registered Electrician or immediately either by chat or via

We take electrical issues very seriously and deal with them with a sense of urgency.

Our qualified, RECI registered and insured Electricians cover all of Cork City and surrounding areas.

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