Limits first, because with electricity the limits are the point. I am a surveyor, not an electrician. On an EPC or a building survey I look at the consumer unit, note its type and apparent age, check the supply is present — and where anything looks wrong, the report says “electrician” and means it. Nothing here is an invitation to open a consumer unit or work on a circuit. This is a guide to the small family of instruments that let you make basic electrical checks safely — is this socket wired correctly, is there voltage here, is this battery flat — and to the instruments that only look like they do that job.
The most important idea comes from the trade: safe isolation. When an electrician needs a circuit dead, they don’t trust the switch, the label in the board, or a glowing pen. They prove their tester on a known live source (that’s what a proving unit is for), test the circuit with a two-pole voltage tester, then prove the tester again. Prove, test, prove. Every serious instrument in this guide serves that discipline, and HSE guidance note GS38 — the document specifying finger guards, insulated leads and barely-there probe tips — is the standard the good ones are built to.
And the neon screwdriver — the pocket screwdriver with the bulb in the handle that every toolbox in Britain seems to contain — works by passing current from the live part through your body to earth. It has no meaningful insulation category, it stays dark when the bulb fails or the contact is poor, and a dark bulb reads as “safe”. GS38 warns against them in terms. It belongs in the bin.
The one I’d buy
Kewtech KT1780
A proper GS38-style two-pole voltage and continuity tester from a respected UK test-gear brand, at a price that makes the neon screwdriver indefensible. LED voltage indication that works even with flat batteries, polarity, continuity with a buzzer, and a torch for exactly the sort of cupboard consumer units live in. This is the baseline instrument for anyone who ever needs to know whether something is live.
Typically £45–£60
Check price on AmazonHow I judge a voltage tester
Two poles, always. A two-pole tester measures between two points — live and neutral, live and earth — the way voltage actually exists. Single-pole devices (neon screwdrivers, and to a lesser degree non-contact pens) infer voltage from capacitive leakage, sometimes through you. The trade proves dead with two poles because a two-pole reading is a measurement; everything else is a hint.
GS38 features. Finger barriers on the probes, fully insulated leads, and exposed metal tips of 4mm or less (2mm is better). These details exist because the failure mode isn’t “wrong reading” — it’s a slipped probe bridging two terminals in a live board. If a tester’s marketing doesn’t mention GS38, its designers weren’t thinking about UK electricians.
Works when the batteries don’t. The best two-pole testers indicate voltage on LEDs powered by the circuit under test, so a flat battery can’t silently turn “live” into “dead”. Some — the Martindale VI13800 is the type specimen — contain no batteries and no fuse at all, which means nothing inside can fail towards a false “safe”. For a device whose whole job is telling you it’s safe to touch something, that logic matters more than any feature.
An honest CAT rating. Overvoltage categories describe where on the supply an instrument can safely face a transient spike: CAT II is appliances and socket outlets, CAT III is the fixed installation and distribution boards, CAT IV is the origin — the cutout, the meter tails. The voltage after the CAT matters too: CAT III 600V beats CAT II 1000V near a board. On premium brands the rating is independently certified; on £20 internet specials it is, at best, an aspiration printed on the case.
Provable. Whatever you buy must be checked against a known live source before and after the reading you care about. That can be a proving unit, and for anything beyond casual use it should be — which is why one is in this list.
The comparison
| Model | Type | CAT rating | Typical price | Best for | |
|---|---|---|---|---|---|
| Kewtech KT1780 | Two-pole voltage & continuity | CAT IV 600V | ~£50 | The baseline safe instrument | View |
| Fluke T150 | Two-pole, LCD + resistance | CAT IV 600V / CAT III 690V | ~£120 | The trade’s daily driver | View |
| Fluke T6-600 | Open-fork FieldSense tester | CAT III 600V | ~£220 | Voltage readings without test leads | View |
| Martindale VI13800 | Fuseless voltage indicator | CAT IV 600V | ~£70 | Proving dead, nothing else | View |
| Martindale PD240 | Proving unit | — (240V DC source) | ~£65 | Prove–test–prove discipline | View |
| Socket & See SOK32 | Plug-in socket tester | — (230V socket) | ~£35 | Socket wiring checks in seconds | View |
| Fluke 1AC-II VoltAlert | Non-contact pen | CAT IV 1000V | ~£27 | Indication only — never proof | View |
| Kaiweets HT118A | Digital multimeter | Marked CAT III 1000V | ~£40 | Batteries and bench work, with caveats | View |
The picks in detail
Kewtech KT1780
Best overall — the two-pole tester to buy first, and my top pick above
Kewtech is the UK arm of Kyoritsu, a Japanese test-equipment firm electricians know well, and the KT1780 is their two-pole tester done properly: LED voltage steps from 12V to 690V, AC and DC with polarity, continuity with a buzzer, a probe-tip torch, and an IP64 body. The detail worth the money is that the voltage LEDs are driven by the circuit under test, so a flat battery degrades the extras, not the “is it live” answer. Owner feedback is consistent on the build feeling like an instrument rather than a gadget, and on the torch being more useful than it sounds — consumer units live in dark cupboards.
For
- Voltage indication works without batteries
- GS38-style probes, CAT IV 600V rating from a proper brand
- Continuity, polarity and a torch in one pocketable body
Against
- LED steps, not a numeric display — fine for presence, not measurement
- Costs more than the no-name testers it will outlast
Typically £45–£60
Check price on AmazonFluke T150
Best professional two-pole — the tester on most electricians’ belts
Walk onto any site and the yellow two-pole tester hanging off the electrician is more often than not a Fluke T-series; the T150 is the one with an LCD readout and resistance measurement on top of the LED bars. It adds a switchable load function that can trip an RCD and suppress ghost voltages, reads down to low AC/DC, and carries Fluke’s certified CAT III 690V / CAT IV 600V rating. Published feedback is what you’d expect of the brand: boring, in the best sense — it reads the same every time and survives being dropped. If testing were part of my job rather than the edge of it, this is where I’d spend.
For
- Actual numeric voltage and resistance readout
- Certified ratings, GS38-compliant probes, legendary durability
- Load function for RCD tripping and ghost-voltage suppression
Against
- Twice the price of the Kewtech for capability most non-electricians won’t use
Typically £110–£140
Check price on AmazonFluke T6-600
The premium pick — voltage and current readings through the fork, no metallic contact
The T6’s party trick is FieldSense: slide an insulated single conductor into the open fork and it displays actual voltage and current numbers without test leads touching bare metal. For electricians working through trays of cables it’s a genuine time-saver, and it still carries conventional leads for voltage, continuity and resistance. Two caveats from the spec sheet: FieldSense needs a single separated conductor — it can’t read through twin-and-earth sheath, where the fields cancel — and it’s a working-measurement tool, not a substitute for a two-pole prove-dead test. Professional overkill for basic checks, but if one tester has to do everything, this is the direction of travel.
For
- Numeric volts and amps through the fork, no bare-metal contact
- Also a conventional leaded tester; Fluke build and certification
- Current to 200A without breaking the circuit
Against
- Serious money; CAT III 600V (the T6-1000 goes higher)
- FieldSense can’t see through multi-core sheathed cable
Typically £200–£260
Check price on AmazonMartindale VI13800
Best dedicated voltage indicator — the purist’s prove-dead instrument
Martindale has been making safe-isolation kit since before it was called that, and the VI13800 is the philosophy distilled: no batteries, no fuse, no switch, no display — just LEDs at 50, 100, 230 and 400V driven entirely by the circuit under test. Nothing inside can go flat, blow or fail in a way that shows “dead” on a live circuit, which is precisely why this style of indicator is what electrical safety trainers hand out. It measures nothing and does nothing else; that single-mindedness is the feature. Paired with a proving unit (below, and Martindale sell them as a kit), it’s the textbook safe-isolation setup.
For
- Fuseless, batteryless — no silent failure to “safe”
- GS38-compliant probes, CAT IV rating
- Nothing to configure, nothing to misread
Against
- Indication only — no continuity, no numbers
- Costs more than the multifunction Kewtech
Typically £60–£80
Check price on AmazonMartindale PD240
The proving unit — the other half of proving dead
A proving unit is a pocket battery box that generates a known voltage — 240V DC here — so you can confirm your tester actually works immediately before and after relying on it. Without one, “the tester shows nothing” has two explanations, and one of them can kill you. The PD240 suits two-pole testers and indicators like the VI13800 and KT1780; electronic testers with higher ranges may want the dearer PD440S. It is the least glamorous item in this guide and the one that turns the others into a safe system.
For
- Completes prove–test–prove — the whole point of safe isolation
- Pocketable, simple, from the brand that defined the category
Against
- Single output voltage; check compatibility with electronic testers
- Feels dear for a battery box — until you need it
Typically £55–£75
Check price on AmazonSocket & See SOK32
Best socket tester — the one legitimate plug-in check anyone can make
This is the electrical check that genuinely is within a surveyor’s (or a landlord’s, or a house-hunter’s) remit: plug it into a 13A socket and three LEDs plus an audible tone report whether live, neutral and earth are where they should be — correct, reversed polarity, or a missing conductor. Socket & See is the UK specialist in these, and the tone-plus-lights system is quicker to read around a house than squinting at LED charts. Know the honest limit, printed on the device itself: no plug-in tester catches every fault — the classic miss is neutral and earth swapped — and it says nothing about the earth’s actual quality. A pattern of odd sockets is evidence for an EICR, not a diagnosis.
For
- Fast, safe, zero-skill wiring check on every socket in a house
- Audible tone means you don’t crouch behind furniture to read LEDs
- UK specialist brand used by the trade
Against
- Cannot catch every fault (N–E reversal, earth quality)
- Green lights get over-read as “this installation is fine”
Typically £25–£40
Check price on AmazonFluke 1AC-II VoltAlert
Best non-contact pen — useful indication, never proof of anything
Hold the tip near an insulated conductor and it beeps and glows if it senses AC field — no contact, no probes. The legitimate uses are real: which of these cables is the live feed, is this ceiling rose worth being careful around, did that fuse actually kill the lighting circuit. The 1AC-II is the one to buy over the £8 versions because Fluke fit a self-test that continuously verifies the sensing circuit, so a dead pen doesn’t sit there quietly reading “safe”. But a non-contact pen is single-pole indication by capacitive coupling, and screening or depth can silence it over a live conductor. It answers “might this be live?”, never “is this dead?”.
For
- Continuous self-test — the feature that justifies the brand premium
- Fast triage of cables, roses and switch drops without touching anything
- Pocket-clip small, batteries last ages
Against
- Indication only — can stay silent over screened or deep live cables
- Also chirps at static and induced voltage on dead conductors
Typically £22–£32
Check price on AmazonKaiweets HT118A
Best budget multimeter — for batteries and bench work, with clear-eyed caveats
Amazon’s bestselling budget multimeter class, and the HT118A is a fair representative: 6000-count auto-ranging display, True RMS, voltage, current, resistance, capacitance, temperature and continuity for the price of two rounds at the pub. For what I’d actually use a multimeter for — is the 9V battery in the damp meter flat, is this thermostat calling for heat, has this extension lead got continuity — owner feedback says it does the job perfectly well. The caveats: the CAT III 1000V marking on a £40 meter hasn’t been through the third-party certification a Fluke’s has, budget input protection is exactly where these meters save money, and the leads are not GS38 items. Bench and battery tool: yes, happily. Proving dead in a consumer unit: no — that’s what the two-pole testers above are for.
For
- Enormous capability per pound for low-energy work
- Auto-ranging and a big backlit display — easy for occasional users
- Fine for batteries, continuity, fuses, vehicle and bench jobs
Against
- CAT markings on budget meters are unverified claims
- Not a safe-isolation instrument; leads are not GS38
Typically £35–£50
Check price on AmazonWhat actually matters — and what doesn’t
Know where checking ends. Worth restating without the product talk. Legitimate territory for a surveyor, landlord or capable homeowner: is the supply present, does the socket tester show correct wiring, is the meter battery flat, does the pen suggest this cable is live so I’ll keep away from it. Electrician-and-EICR territory: anything involving opening the consumer unit, testing circuits, earth loop impedance, RCD performance, or deciding an installation is safe. An EICR — Electrical Installation Condition Report — is a few hundred pounds from a registered electrician, it’s already mandatory for private rentals in England, and no quantity of Amazon test gear substitutes for it. My reports flag electrical concerns; they never clear them.
CAT ratings, decoded once more. The category is about transient spikes, not steady volts: mains circuits carry brief multi-kilovolt transients from switching and lightning, and the closer to the supply origin, the fatter the spike. CAT II covers plug-in appliance level, CAT III fixed wiring and distribution boards, CAT IV the supply side — cutout, tails, meter. An instrument facing a transient beyond its category can flash over internally, and with your hand on it. For anything used near a consumer unit, CAT III 600V from a certified brand is the sensible floor — and certification (a genuine UKCA/CE backed by TUV, UL or similar marks) is what separates a rating from a sticker.
What the marketing pushes that you can skip. For basic checks: True RMS (matters for distorted waveforms in industrial settings, not for “is this live”), 20,000 counts (precision beyond any question you’re asking), Bluetooth apps and data logging. The unglamorous things — lead quality, finger barriers, fused or current-limited design, a self-test, a case that survives the van — are where the money should go. A £50 two-pole tester with GS38 leads is safer and more useful than a £50 multimeter with a spec sheet the length of this page.
One tester does not make you an electrician. The trade joke about the most dangerous thing on site being a labourer with a multimeter exists for a reason. The instruments here answer narrow questions safely. The moment the question becomes “why is it wired like this?” or “can I move this?”, the answer is a registered electrician, and in England any notifiable work falls under Part P of the Building Regulations besides.
Questions I get asked
Can I use a multimeter to check if a wire is live? A quality multimeter set to AC volts can read voltage, but electricians don’t prove dead with one, and the reasons apply double to amateurs: a multimeter left on ohms or amps and touched to a live circuit can fail explosively; a wrong range, a flat battery or a broken lead can all read “0V” on a live conductor; and budget meters lack certified input protection. A two-pole voltage tester has one job, fails safe, and costs less than the multimeter’s replacement fuses. Use the multimeter for batteries and continuity; use a two-pole tester for “live or dead”.
What voltage tester do electricians actually use? A GS38-compliant two-pole voltage indicator or tester — the Fluke T-series, Kewtech, Martindale and Di-LOG units you see on every site — proved against a proving unit before and after each test. That’s the safe-isolation procedure the industry codified after too many people trusted a switch or a screwdriver bulb. Non-contact pens are carried too, but for triage, never for proving dead.
Are non-contact voltage testers reliable? They’re reliable at what they do — sensing the AC field around an unscreened live conductor — and unreliable as a safety decision, because absence of a beep is not absence of voltage. Screened cable, metal capping, depth, even probe orientation can silence one over a live cable, and conversely induced voltage makes them chirp on dead conductors that run alongside live ones. Buy one with a self-test (that’s the case for the Fluke over the bargain bin), use it to decide where to be careful, and never let it tell you something is safe to touch.
Do I need a proving unit? If a tester’s reading will ever be the reason you touch a conductor, yes. The logic is unforgiving: a tester that shows nothing is either reading a dead circuit or is itself broken, and you cannot tell which without a known live source. A proving unit is that source in your pocket — no hunting for a live socket that may itself be on the circuit you just isolated. For plug-in socket checks and battery testing you can live without one; for anything resembling isolation, it’s the cheapest life insurance in the toolbag.
If the state of a property’s electrics is the real question, that’s survey territory. On an EPC assessment I inspect what’s visible — consumer unit, meter, heating controls — without testing circuits, and a building survey will tell you plainly when an installation needs an EICR from a registered electrician — get in touch. And if you’re assembling a survey bag, there are more field-kit guides.
Small print. This guide is general information, not electrical advice or training; electricity can kill, work on fixed installations is a job for a registered electrician, and in England notifiable electrical work falls under Part P of the Building Regulations. Prices are indicative, move constantly and were checked at the time of writing; the linked page always shows the current price. As an Amazon Associate I earn from qualifying purchases.