Martindale EZ150 Socket Tester with Earth Loop Impedance

In-Depth Look

The Martindale EZ150 is a plug-in socket tester that can be used alongside a multifunction tester. It provides a fast first look at socket condition without the setup time and calibration of a full loop impedance measurement with a multifunction instrument.

Fault Detection

Martindale lists the wiring faults the EZ150 detects as phase-neutral reverse, phase-earth reverse, phase fault, neutral open and earth open, plus under and over voltage. It also shows the earth loop impedance in one of six bands, from 0-1.7 ohms up to 200-500 ohms, using LEDs rather than a numeric display. This gives an indication of the fault before further investigation with a full instrument.

T-Safe Non-Trip Technology

The T-Safe technology is the EZ150’s main feature. When performing the earth loop impedance check, the test current is carefully controlled to remain below the trip threshold of installed RCDs. Some loop testers can trip 30mA RCDs, cutting power to the circuit. T-Safe is designed to avoid this, allowing loop impedance measurement across a full installation without interrupting supply to sockets or appliances. This is useful in occupied homes, offices and multi-unit properties.

Limitations

The EZ150 is a supplementary tool, not a substitute for a full EICR with a calibrated multifunction tester. It does not replace a Fluke or Megger instrument for ring circuit continuity, insulation resistance, or full Zs measurement. Its value is speed: plugging the EZ150 into each socket on a visual inspection tour gives an instant fault indicator before committing to a full electrical test.

Verdict

The Martindale EZ150 goes beyond a basic pass/fail socket tester. Its wiring fault detection, earth loop impedance bands and T-Safe non-trip technology make it a useful pre-screening tool for quick socket checks on occupied premises. It gives an indication only and does not replace full testing.

How It Compares

The Martindale EZ150 is a plug-in 13A socket tester powered from the socket itself. Three LEDs show wiring conditions: live and neutral reversed, live and earth reversed, a live fault, an open neutral and an open earth. A second group of three LEDs indicates the earth loop impedance as one of six bands, from 0 to 1.7, 1.7 to 5, 5 to 10, 10 to 100, 100 to 200 and 200 to 500 ohms, with a tolerance of plus or minus 10%. It also flags under-voltage below 195V and over-voltage above 270V, and it is rated CAT II 300V.

Its T-Safe feature checks loop impedance without tripping 30mA RCDs and RCBOs. Martindale describes it as the first socket tester to include earth loop impedance.

The EZ150 is a quick screening tool. It can show up a problem during a visit, but it does not replace an electrical installation condition report, known as an EICR, or any formal testing. Those need a calibrated instrument and a competent person.

A plug-in tester suits spot checks, such as when you move into a property or before plugging in a tool. It is not a substitute for periodic inspection. Treat any warning as a reason to stop using the socket and ask a qualified electrician to investigate. Keep the tester dry and clean, and do not use it if the case is cracked or the pins are damaged.

Common Questions

What does a basic three-light socket tester not tell me? It checks for a limited set of wiring faults. It does not show whether the earth path is good enough for a protective device to operate quickly in a fault, because it does not measure impedance. This is the gap the EZ150 narrows by showing a band.

What do the loop impedance lights mean, and is this a full test? The lights show which of six bands the loop impedance falls into. It is an indication, not a full test. Formal testing needs a calibrated instrument and a competent person, who compares readings with the limits for the protective device on the circuit.

Why does a loop tester sometimes trip an RCD, and how does T-Safe avoid that? A loop test works by driving a current through the earth path, and if that current is large enough it can look like an earth fault to a 30mA RCD or RCBO, which then trips. T-Safe is Martindale’s patented method for checking loop impedance in bands without tripping these devices, so a protected circuit can be checked without it cutting out.

What should a landlord do after a fail light? Stop using the socket and call a qualified electrician. A fail light on this tester points to a problem but does not diagnose it, and it does not replace an EICR. Follow the manufacturer’s instructions and use a competent person where required.