Meet the latest additions to the Martindale socket tester family: The BZ701, EZ165 & EZ365 Socket & Supply Testers

over 2,000,000 Check Plugs

have been manufactured to date – our best estimate!

Why test sockets?

A socket tester is used to test whether a wall socket is correctly wired and also check for common faults such as no earth connection and short circuits.

Sockets are the most common source of electrical power in homes and commercial buildings. However, it is not uncommon to find sockets damaged, broken or inadequately wired.

Suitable for use as a first line indicator to identify potentially unsafe installations and wiring faults.

For use prior to carrying out work on existing installations or connecting new appliances, or to identify socket outlets which may require a more detailed inspection as part of periodic inspection and testing.

Socket testers offer a fast and effective solution.

training and support

Choosing the right socket tester

The CP501 Check Plug and BZ101 Buzz-It are the UK’s favourite socket testers designed for easy verification of wall socket wiring.


Unlike most other socket testers, not only does the Martindale BZ701 detect 28 socket wiring fault conditions and check the mains voltage level, but it also safely detects Line-Neutral reversal (cross polarity) at the incoming supply. The BZ701 offers advanced 13A socket testing capability in a wide variety of domestic, commercial and industrial applications.


The EZ165 gives quick & easy mains socket polarity and earth testing with the ability to detect 28 fault conditions and check the mains voltage level. It can also show how safe the earth wiring is by carrying out a non-trip earth loop test and indicating its value in 6 discrete ranges. A low earth resistance is essential for safety disconnection devices to work properly and prevent electrocution when faults occur.


The EZ365 can detect 28 fault conditions, mains voltage level and perform a non-trip earth loop test. It also has the ability to check for L-NE polarity swap at the incoming supply and can be used to trip test 30mA RCDs. The L-NE cross polarity test detects a serious fault condition that cannot be identified by normal socket testers and is easily activated by using the touch pad on the EZ365.

Indicates a functional socket
Indicates 28 fault conditions
Detects presence of earth
Extra 4mm Earth Connection
LED Indication
Audiable indication
Display range of earth loop impedance values
Live neutral polarity check
30mA RCD trip check
High & Low Voltage Indication


– Indicate functional socket

– Detect line / neutral reversal

– Detect presence of earth


– Indicate functional socket

– Detect line / neutral reversal

– Detect presence of earth

– Display range of earth loop impedance values


– Indicate functional socket

– Detect line / neutral reversal

– Detect presence of earth

– Display the numerical value of earth loop impedance

What do they do?

Our socket testers can accurately indicate up to 28 faults, the most common of which can be interpreted from the quick key on the front of the tester with further details clearly shown on a useful instruction card supplied with all Martindale socket testers.

For more information on advanced and professional socket testers as defined by the Health & Safety Executive, read our article on how to choose the right socket tester for the job.

What don't they do?

It’s important to recognise that although socket testers can be used for detecting first line fault conditions, they are not an alternative to full verification of wiring installations. For full verification it’s necessary to follow the inspection and testing procedures set out in BS 7671, using a full set of test instruments complying with the relevant parts of BS EN 61557, typically with a multifunction electrical tester such as a Martindale ET4000.

Find out more about our socket testing range

Martindale Classic Check Plug Socket Tester


Martindale Buzz-It Socket Tester with Audible Buzzer


Martindale Socket & Supply Tester


Martindale Socket & Non-Trip Earth Loop Tester


Martindale Socket, Earth Loop
& RCD Tester


Martindale Socket Tester with Earth Test Point



To supplement our website, which provides information on all of our socket testers, we’ve created additional guides related to the subject.

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