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What Is An RCD

This web page explains what an RCD is and answers basic questions about RCDs.

 

 

What Does RCD stand For?

RCD stands for Residual Current Device.

 

 

Why use RCDs?

RCDs protect against electrical shocks – death and injury.

 

 

What Is An RCD?

An RCD is an electrical safety switch that remove the electrical supply to an electrical circuit when the circuit is unsafe.

 

An RCD provides protection against shorts to earth, for instance if a you touch a live conductor or melt a kettle power cable such that the live and earth touch.

 

 

What Does An RCD Check?

An RCD compares the amount of electrical current flowing into an electrical appliance with the amount of electrical current flowing out of an electrical appliance. If the difference is too big the RCD trips.

 

You can't destroy energy (electrical current). The 'missing' electrical current flow is flowing somewhere, just not where it is supposed to flow, i.e. their is a major electrical fault.

 

 

Are RCDs A Legal Requirement In The UK?

Whatever the legal arguments it is good electrical practise to install RCDs.

 

Be aware their are many different answers to this simple question.

 

Yes. Explicitly required at new installations at places of work (17th Edition).

 

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.

 

No – domestic residences (probably!). Most electricians will not install new electrical circuits without an RCD; all electrical work has to be safe. Most electricians interpret that a safe electrical circuit has to have an RCD.

 

 

What Type of RCDs Are Available?

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.

 

 

How Much Are RCDs?

About £50 (January 2015).

 

 

What Do I Do If An RCD Trips?

Reset the RCD.

 

If the RCD trips again investigate why. How to investigate a tripping RCD

 

 

What Is The Difference Between A Fuse And An RCD?

A fuse checks for too much current. An RCD is not bothered about the level of current, just the difference between the current flow in and the current flow out.

 

 

What Is The Difference Between A Circuit Breaker And An RCD?

A circuit breaker checks for too much current. An RCD is not bothered about the level of current, just the difference between the current flow in and the current flow out.

 

 

How Do I Tell The Difference Between A Circuit Breaker And A RCD?

An RCD will have a small test button on the front – push the test button and the RCD should trip.

 

 

What Value Of RCD Should A Domestic RCD Be?

30 milliamperes.

 

This means the RCD will trip when their is a difference 30 greater than 30 milliamperes between the current in and the current out.

 

RCD Links

Judge Electrical RCD home page

 

How to reset an RCD

 

RCD tripping

 

RCD Images

 

Judge Electrical Limited
15 Mulberry Court, Huntington, York, YO32 9TU
Telephone 01904 764845 (Landline), 07919 033113 Mobile)
Email info@judgeelectrical.co.uk
VAT No. 852917405. Company Number 6359328