There is a huge range of socket testers available on the market offering testing capability in a wide variety of domestic, commercial and industrial applications. These simple top ten questions and answers will help identify which is the best solution for your application.


1. I want to buy a Socket Tester, but there are so many available; how do I choose?

There is a huge variety of Socket Testers on the market. As a result, it can be challenging to choose which one is best suited to your application. Generally, Socket Testers can be split into three categories: Simple, Advanced and Professional. All socket testers will check that basic connections have been made correctly; however, advanced and professional socket testers will have more functionality with respect to earth testing.


2. So, which tests will a Simple Socket Tester perform?

All testers check that a socket is functioning; this includes checking for live and earth reverse, Live and Neutral reverse and that there is earth connected. However, they do not check if the socket is adequately earthed for safety. Some offer added features. This may include a buzzer in addition to LEDs to indicate a good socket, or they may show a combination of indicators to identify which particular fault type is present.


3. What is the difference between an Advanced and Professional Socket Tester?

The key differentiator is related to checking the effectiveness of the protective earth. Advanced testers usually indicate the range of the loop impedance value via LEDs – examples are the Martindale EZ165 and EZ365. Professional testers have the ability to show numerical values for earth loop impedance. A reliable earth loop impedance measurement is essential to ensure that over-current protection devices achieve a fast enough disconnection time to avoid electrocution.


4. I’ve heard there’s a test that no Socket Tester can perform. What is it, and why?

There is one fault that a socket tester and indeed no other piece of equipment can easily find, the swapping of the Earth and Neutral wires. This is because the earth and neutral are common at the substation (if not closer), so electrically, they are indistinguishable.


5. What is the “supply reversed” test on some socket testers?

This is a cross-polarity test. Although all socket testers are capable of identifying wiring faults at the socket, including Live-Neutral errors, they will not detect when the incoming supply polarity has been reversed. This serious fault condition where L-NE connections have been reversed at the supply and require a special additional test. The latest addition to the Martindale range, the BZ701, has this feature.


6. Will my Socket Tester test an RCD?

A socket tester will only check the functionality of an RCD in a circuit, the ability to trip. RCD testing requires the use of an RCD tester or multifunction installation tester with RCD test capability.


7. Does a Socket Tester help with 18th edition installation testing?

It’s important to appreciate that socket testers are not an alternative to the full verification of wiring installations. For testing installations, professional loop testers and multifunction testers suitable for carrying out all the tests needed to verify the safety of domestic, commercial and industrial wiring installations according to the 18th Edition Wiring Regulations are required.


8. In summary, what can I use a Socket Tester for?

A socket tester is a first-line indicator to identify potentially unsafe installations and wiring faults. Socket testers offer a fast and effective solution when properly specified. They can also be particularly useful as a service tool in identifying potentially unsafe conditions prior to carrying out work on existing electrical systems and equipment or before installing new appliances.


9. I need to check Industrial Sockets. Can a Socket Tester help?

Manufacturers such as Martindale, offer a full range of industrial socket testers, specifically for this application. These perform some of the basic tests similar to standard 13A socket devices but offer different pin configurations, different voltage levels, and three-phase checks.


10. Where can I find more information?

The Electrical Safety First guidance note Best Practice Guide 8 (version 2) “Selection and Use of Plug In Socket Testing Devices”, is an excellent source of information.