Best Multifunction Tester UK: A Working Spark's Verdict

Quick answer

For most UK electricians the Megger MFT1741+ is still the best all-round multifunction tester: the most trustworthy no-trip loop test in the business, Type A and Type B RCD coverage, and Bluetooth download into certification software, with Megger's own UK service operation behind it. On a tighter budget the Kewtech KT66DL does the vast majority of the same job for mid-range money. For heavy commercial and industrial testing with hundreds of circuits to record, the Metrel MI 3152 is the data-handling king.

What actually matters when you're choosing an MFT

Every mainstream MFT sold in the UK is built to BS EN 61557 and will do the core 18th Edition test sequence: continuity (R1+R2), insulation resistance at 250, 500 and 1000 V DC, earth fault loop impedance, prospective fault current and RCD trip times. On paper they all pass. The differences that matter on site are these.

RCD types. Since BS 7671:2018+A2:2022, Type AC RCDs are effectively on their way out for new work. Regulation 531.3.3 requires the RCD type to suit the loads it protects, and with DC leakage from electronics everywhere, Type A is now the default and Type B turns up on EV chargers and drive-fed equipment. Any tester you buy in 2026 must test Type A properly. Whether it also does Type B is one of the main things separating the flagships from the mid-rangers, and if you're pricing EV charger installs it stops being optional.

No-trip loop accuracy. This is the single biggest real-world differentiator. A standard high-current loop test will trip a 30 mA RCD, so on protected circuits the tester uses a low-current method instead, and low-current tests are inherently noise-sensitive. Anyone who has watched a no-trip Zs reading wander between 0.4 and 1.1 ohms on the same socket knows the frustration. The better instruments manage this far better than the cheap ones, and it matters, because a flaky Zs reading against the maximum Zs values is the difference between signing a circuit off and chasing a fault that isn't there. Sanity-check any suspicious no-trip reading against Ze plus your measured R1+R2 before you start pulling boards apart.

Build quality. You want dials you can turn with gloves on, a case that survives being trodden on in a loft, and leads that don't fail at the strain relief in six months.

Calibration ecosystem. The scheme providers expect evidence of ongoing accuracy, and the accepted norm is annual calibration with a traceable certificate. All four big brands are covered by the UK calibration houses, but manufacturer-backed UK service matters when a unit fails, not when it's working.

Software and cert export. If your work is EICR-heavy, on-board memory and Bluetooth download are not luxuries. Typing two hundred readings from a soggy notepad into cert software at 9 pm is exactly how transposition errors end up on certificates.

Warranty. Check registration terms. Megger, notably, extends the warranty when you register the instrument, which tells you something about how they expect them to last.

The contenders

Megger MFT1741+: best overall

The Megger MFT1741+ is the tester I reach for and the one I've specified for test engineers on contract work. The two-rotary-dial layout is the best interface in the industry, fully usable with gloves on, and the IP54-rated case shrugs off the sort of abuse a food factory hands out.

The killer feature is the loop testing. It does both two-wire and three-wire no-trip methods, and the Confidence Meter shows you graphically how stable the reading is, so you know whether to trust that Zs or repeat it. Nobody else gives you that visibility. RCD coverage runs through AC, A and Type B, so EV chargers and drive-heavy plant rooms don't send you back to the wholesaler. Results store on board and push over Bluetooth into Megger's CertSuite certification software, and the instruments are serviced by Megger in Dover rather than shipped abroad.

The honest downside is money. This is flagship pricing, and if you do a handful of certs a month you are paying for capability you won't use. That buyer should read on.

Kewtech KT66DL: best value for money

The Kewtech KT66DL is the default recommendation I give domestic sparks, and I have never had one come back and complain. Kewtech is the UK arm of Kyoritsu, so the build is Japanese instrument-making rather than budget-brand plastic, and it's noticeably lighter around your neck than the Megger on a full-day EICR.

Its party piece is ATT, Kewtech's anti-trip loop technology, which is genuinely good: stable no-trip readings on RCD-protected circuits without the ritual of testing three times and taking the middle number. The auto RCD sequence runs the full set of tests from one press, which saves real legs-up-the-stairs time, and the DL model stores results and downloads over Bluetooth into cert software.

Limitations: RCD testing covers Type AC and Type A, so if Type B testing is on your horizon, this isn't your tester. For the domestic and light commercial spark it does 90 per cent of what the flagship Megger does for mid-range money, and that's why you see so many in vans.

Fluke 1664 FC: the one that won't let you cook the customer's telly

The Fluke 1664 FC has one feature nobody else offers and every one of us has needed at least once: Insulation-PreTest. If an appliance is still connected to the circuit when you go to do an insulation test, the tester detects it and stops before you put 500 volts through someone's brand-new smart TV. If you've ever had that sickening moment, you know exactly what that feature is worth.

Beyond that it's a proper flagship: an auto test sequence that runs the required tests in one operation, RCD coverage including Type A and smooth-DC Type B, and wireless results sharing to your phone through the Fluke Connect app. Build quality is classic Fluke, which is to say it will outlive the van.

The honest criticism is that the software side is less UK-certification-focused than Megger's CertSuite pipeline, so factor in how your results will actually get onto a certificate. It also sits at similar money to the Megger, so the choice between them usually comes down to PreTest versus the Confidence Meter.

Metrel MI 3152: the commercial and industrial data machine

The Metrel MI 3152 EurotestXC is the least familiar name on this list for a lot of UK sparks, and the most capable instrument here in raw functional terms. Colour touchscreen, programmable auto sequences, and a memory structure that mirrors the installation itself: site, distribution board, circuit, result. On a factory EICR with forty boards, that structured memory plus the free ES Manager PC software will save you hours of admin per visit, not per job. RCD coverage includes Type AC, A and B, and Metrel's optional adapters extend it into three-phase and EVSE testing.

Downsides, honestly stated: the learning curve is real, the touchscreen-driven interface is less pleasant with wet or gloved hands than a Megger dial, and because fewer UK sparks carry them there's less on-site folklore to lean on when you're stuck. This is a tester for people who test at scale. If that's you, nothing else here touches it.

Megger MFT1711: best first MFT on a budget

The Megger MFT1711 is the entry point to the MFT range and my usual answer for a newly qualified spark buying their first tester. Same rugged case and dial layout as its bigger brothers, and the core tests, loop, RCD including Type A, insulation, continuity, are done properly. What you give up is the memory, download and Type B capability, so results go down on paper. For domestic work and building experience, that's a perfectly good trade, and the money you save goes on the rest of the first-year tool kit.

Megger MFT-X1: the future-proof option

Worth a brief mention: the Megger MFT-X1 is Megger's newer flagship, built around updatable firmware so the instrument gains capability over its life rather than going stale. It covers the full RCD spread including Type B and adds 6 mA RDC-DD testing, which is directly relevant to EV charger verification. It is serious money and overkill for most domestic work, but if EV installation is a core part of your business it's the most future-proof box on this page.

Head to head

Tester	No-trip loop	RCD types	Memory / download	Best for
Megger MFT1741+	Excellent, Confidence Meter	AC, A, B	Yes, Bluetooth to CertSuite	Best overall
Kewtech KT66DL	Excellent, ATT	AC, A	Yes, Bluetooth	Best value
Fluke 1664 FC	Good	AC, A, B	Yes, Fluke Connect	Insulation PreTest, durability
Metrel MI 3152	Good	AC, A, B	Yes, structured memory, ES Manager	Commercial / industrial scale
Megger MFT1711	Good	AC, A	No	Budget first MFT

Verdicts by use case

The domestic sparky

Buy the Kewtech KT66DL. It covers everything a domestic installer and EICR contractor needs, the ATT loop testing is dependable, and the saving over a flagship pays for two or three years of calibration. Step up to the Megger MFT1741+ if your certificate volume is high enough that the CertSuite pipeline and the Confidence Meter earn their keep, or if EV chargers are creeping into your workload.

Commercial and industrial

The Metrel MI 3152 if your problem is scale and data, the Megger MFT1741+ if your problem is hostile environments and you value the interface, and the Megger MFT-X1 if EV infrastructure is a major revenue line. Type B capability is non-negotiable at this level; you will meet drive-fed and EV loads, and turning up without the means to test them is a bad look in front of a client.

First MFT on a budget

The Megger MFT1711 new, or a clean secondhand mid-range Megger or Kewtech with a fresh calibration certificate. Do not buy any secondhand tester without pricing in an immediate calibration and probably a new lead set; both together can eat a surprising chunk of the saving. And avoid grey imports whatever the brand, because the warranty and UK service support are half of what you're paying for.

FAQ

Do I really need Type B RCD testing?

For pure domestic work today, no, Type A coverage is the essential. But EV charger installations and anything fed through variable-speed drives can involve Type B devices or 6 mA DC detection, and if that work is in your plans, buy the capability now rather than replacing a tester in two years. Our EV charger testing guide covers what those jobs actually demand.

How often does an MFT need calibrating?

Annual calibration with a traceable certificate is the accepted industry norm and what the scheme assessors expect to see. Many of us also use a calibration check box between calibrations to prove ongoing accuracy, which is cheap insurance if your tester takes a knock mid-year.

Are cheaper MFTs accurate enough for EICR work?

If it's BS EN 61557 compliant and in calibration, its results are valid, and a calibrated budget tester beats an out-of-calibration flagship every time. What you're really paying for at the top end is repeatability on no-trip loop tests, Type B coverage, and a workflow that gets hundreds of readings onto a certificate without transcription errors. On EICR work, that last one matters more than people admit.

Is the times-5 RCD test still required?

Current Guidance Note 3 practice under the 18th Edition calls for the test at 1x the rated residual current, with the ramp test available as a diagnostic tool. The old half-times and five-times ritual is a habit from a previous era, though plenty of auto-test sequences still offer it.

Which tester holds its value best secondhand?

Megger, comfortably, with Fluke close behind. Kewtech units sell steadily at sensible money. Metrel's resale market in the UK is thinner, which cuts both ways: worse when you sell, but a genuine bargain opportunity when you're the buyer with cash for a lightly used MI 3152.