Why do you need RCD protection?

Why do you need RCD protection?

RCD in fuseboard

A fuseboard with RCD protection

How does RCD protection work? To understand what an RCD does we must first understand what an electrical safety switch is. An electrical safety switch is a device that will cut off or divert the flow of electricity.

An RCD (Residual-current device) prevents current from flowing when there is more current passing through the live than the neutral. Energy cannot just ‘disappear’. If there is more flowing In than out, It must be going somewhere other than the neutral. An RCD will trip in this scenario as this means something is wrong.

Furthermore, if you have RCD protection you will not be protected from overcurrent or short circuits. An RCD must not be confused with ‘circuit breakers’ or more typically known as ‘circuit protection fuses’. If you have RCD protection It will only trip if there is an imbalance. A ‘circuit protection fuse’ will trip in a short circuit or overcurrent situation. That is the difference between the circuit breaker and RCD.

There are now devices that Include both and these are known as ‘RCBO’. More on that later.


Why is your RCD tripping?

Central heating

Central heating involves electric, water and metal pipes. A potential minefield and unsurprisingly is a very common cause of RCD tripping. Water can leak where it shouldn’t due to a leaky pipe into the central heating electrics. A common cause for an RCD tripping intermittently is when your boiler is firing up and water starts toflow. Or if your rcd tripping every few hours is due to the central heating. If your rcd keeps tripping randomly, rain can get into the flue and cause the RCD to trip. Condensation can be a big factor too.

What Is Earth Leakage Current?

Earth leakage current is an electrical current that is flowing to earth because of a fault in electrical wiring or fixtures and appliances connected too it. An earth leakage fault can be very frustrating and finding the causes of leakage current can be tricky. In a perfect world there would be no earth leakage in an electrical wiring system. In the real world it can be perfectly normal to expect some earth leakage current. Some causes of earth leakage current can be computers which is why in large offices rcd protection can be tricky. In domestic households, you will your rcd protection has a tolerance of 30 mA . This is 0.03 of an Amp. This doesn’t sound like much but it only takes 0.05 of an amp to kill. If you are having enough earth leakage that your rcd is tripping you need to call an electrician.


Are RCDs A Legal Requirement In The UK?rcd switch rcd protection

A common issue homeowners face when wanting to upgrade their electrics is the requirements of RCD protection. Aside from the legal standpoint, it is considered good practice to have RCD protection in your home. They save thousands of lives every year and help prevent electrocutions and electrical fires. As of the latest edition of the IET wiring regulations. Almost all new circuits or alterations to existing circuits will need to have RCD protection installed. Although this can be provided by ‘RCD plugs’ or ‘RCD sockets’. This is not a long-term solution and they are quite bulky and can look out of place in a modern home. If you have an outdated fuse board you will need to have your fuse board upgraded to accommodate RCD protection.

Yes – implied at HMOs and other rental properties.Landlords have a legal requirement to provide an environment that is safe, an RCD is a very good way of providing electrical safety.


What RCDs are there?

Fixed RCDs that fit in your consumer unit (fuse board).

Built in RCDs (socket) – part of an electrical socket.

Portable RCDs – can plug into any electrical socket.



Example of an RCB

What is an RCBO?

You may have heard of the term RCBO and been confused between an RCD and RCBO.  An RCBO stands for a residual current circuit breaker with overcurrent protection. They have been gaining traction over the past few years as they provide a much more convenient way to provide RCD protection while avoiding nuisance trips. It combines ‘miniature circuit breakers’ or what’s also known as ‘circuit protection fuses’ with RCD capability. It can detect earth faults and disconnect in the event of a short circuit and over current situation. The cons are that they are more expensive than having traditionally two RCDs and MCBs.


Can RCDs be relied upon?

The answer to the question is an astounding YES!! As long as you are pressing the ‘test’ button on your RCD regulary, nearly 100% of the time an RCD will activate in the event of a fault. RCDs are very sensitive devices which have parts inside that activate under very low tolerances. With age and corrsion it can cause parts to stick together inside the RCD which unfortunately means when it goes to activate, it cannot.

If you press the test button on your RCD roughly once every 3 months you will ensure smooth operation in the event of a fault. Furthermore, despite the reliability of RCD protection it is does not reduce the need to be careful around electricity. It is essential if you have any fault in your electrical wiring to call EDB Electrical Services to fix it.

How can I find out whether or not I have RCD protection in my home?

Go to your consumer unit (fuse board) and see if you can locate amongst the circuit breakers ‘T’ or ‘Test’ on one of the devices. Typically there will be a yellow button engraved with the letter ‘T’ with ‘Test’ above it. The RCD unit will often be more chunky than the surrounding miniature circuit breakers. Although It is possible you have RCBO in which case you should still see the ‘Test’ and button on the device. If you do not see any devices that fit the description mentioned then most likely you do not have fixed RCD protection. In which case it may be worth upgrading to have RCD protection installed. This may mean you need an electrical rewire. Electrical safety is important.