Every sparky knows the job. The safety switch on the shop’s power circuit drops out twice a week, always after hours, never when you’re on site. You reset it, test it with an RCD tester, everything passes, and you leave. Two days later the phone rings again.

Intermittent earth leakage is one of the most expensive faults in Australian electrical work, because the cost isn’t in the repair — it’s in the return visits, the lost stock in a cold room, the production line that stopped, and the customer who starts to wonder whether you actually know what you’re doing.

The reason it’s so hard to pin down is simple physics. Under AS/NZS 3000, RCD protection is now standard across most final subcircuits, and a 30 mA device is permitted to operate anywhere between 50% and 100% of its rated residual current. That means a board sitting at 18 mA of standing leakage isn’t faulty — it’s just one kettle, one damp motor winding, or one extra inverter away from tripping. A pass/fail RCD tester will never show you that. You need to see the actual number, and you need to see it while the plant is running.

That’s exactly the job the Hioki CM4002 AC Leakage Clamp Meter was built for.

What the CM4002 actually does

The CM4002 is a dedicated true-RMS earth leakage clamp meter. Instead of measuring current in one conductor, you clamp all the live conductors of a circuit together — active and neutral on a single-phase final subcircuit, or all three phases plus neutral on a 415 V feeder. Under healthy conditions those currents cancel, and the meter reads close to zero. Whatever’s left over is the vector sum: current that has found a path back to earth. That’s the zero-phase current, and it’s the same quantity the RCD upstream is watching.

Six ranges span 6.000 mA, 60.00 mA, 600.0 mA, 6.000 A, 60.00 A and 200.0 A, with a defined accuracy range from 0.060 mA to 200.0 A. The bottom range resolves to 0.001 mA. That span matters more than it looks: the same instrument that resolves a microamp-level insulation problem in a control cabinet can also read the 80 A load current on the feeder beside it, so you’re not swapping tools mid-diagnosis.

Basic accuracy is ±1.0% rdg ±5 dgt from 45 Hz to 400 Hz across the 6.000 mA to 6.000 A ranges — comfortably inside the band where a 50 Hz Australian installation lives.

Readings you can defend, backed by IEC/EN 61557-13

Any clamp will show you a number. The question is whether that number survives scrutiny when you put it in a report.

Hioki designed the CM4002’s current transformer specifically to answer that. The core and shielding are built from high-permeability magnetic materials and the CT is wound with a uniform coil, and the instrument complies with IEC/EN 61557-13 Class 2, 30 A/m — the international performance standard written specifically for leakage clamp meters. Three practical consequences follow:

Position inside the jaw stops mattering. Sensitivity is uniform across the aperture, so a fat two-core bundle jammed against one side of the jaw reads the same as one perfectly centred. In a densely wired distribution board, “perfectly centred” is a fantasy.

Neighbouring busbars stop lying to you. Shielding blocks external magnetic fields, with the effect of a 400 A/m external field at 50/60 Hz specified at 4 mA or less. When you’re clamping a 15 mA leakage path 50 mm away from a loaded 415 V busbar, that specification is the difference between a diagnosis and a guess.

Inverter noise can be filtered out. A switchable low-pass filter with a −3 dB point at 180 Hz ±30 Hz strips high-frequency capacitive leakage from variable speed drives, solar inverters and switch-mode supplies. This is the feature that quietly earns its keep on modern sites. The EMC filters inside a VSD or a PV inverter dump genuine — but harmless — high-frequency current to earth. An unfiltered clamp adds all of it to the reading and sends you hunting a fault that doesn’t exist. With the filter on, the CM4002 sees the installation roughly the way a Type AC or Type A RCD sees it: at power frequency, where tripping decisions are actually made.

Ø40 mm jaw, built for real switchboards

The jaw opens to a Ø40 mm conductor diameter with jaw dimensions of 75 mm × 20 mm. That’s enough to take a three-phase-plus-neutral bundle on a submain, a large single cable, or several smaller circuits at once when you’re bisecting an installation to isolate the offending branch. Undersized jaws are the most common reason a leakage clamp ends up unused in the back of a ute — this one goes where the work is.

Catching the fault that only happens at 3am

This is where the CM4002 separates itself from a basic leakage clamp.

Fit the optional Z3210 Wireless Adapter and the meter gains Bluetooth®, connecting to Hioki’s free GENNECT Cross app on a phone or tablet. Two workflows open up:

Event recording. Set a leakage threshold and a recording window, clamp the meter onto the suspect circuit, and walk away. The instrument logs trip start times, trip stop times and maximum current values to internal memory — up to 999 events, over a recording period of up to 30 days (battery life permitting). You don’t need to stay connected to the tablet while it records. Come back, pull the data into GENNECT Cross, and you have a timestamped picture of an intermittent fault that no amount of standing in front of a switchboard would ever have given you.

Photo drawing for routine inspections. Photograph the board, then tap measurement locations on the image and drop the live readings onto the photo. Work upstream to downstream, and the fault location builds itself visually as you go. You can export a PDF report on site, before you’ve left the customer’s car park — which does more for repeat work than any amount of marketing.

With the Z3210 fitted, GENNECT Cross will also display current harmonics up to the 30th order, along with content factor and total harmonic distortion — useful context when leakage and power quality problems are tangled together on the same site.

Prefer to leave the phone in your pocket? The Excel® Direct Input function types measured values straight into a spreadsheet on a connected device each time auto-hold captures a reading. For calibration technicians and facilities teams doing scheduled runs across dozens of circuits, that’s an entire transcription step — and an entire class of transcription error — deleted.

The details that matter on a long day

• Dual readout shows current and frequency simultaneously, so you can spot straight away when a reading is dominated by something other than 50 Hz.
• Auto hold waits for the value to stabilise, then locks it — for when the meter is at arm’s length inside a board and the display isn’t.
• Comparator gives audible and visual pass/fail against a threshold you set. Eyes stay on the work, not the screen.
• Max / Min / AVG / PEAK MAX / PEAK MIN capture, plus inrush current measurement for motor and transformer starts.
• 48 hours of continuous running on two AA alkalines (about 30 hours with the Z3210 fitted and communicating). Batteries you can buy at any servo in the country.
• −10°C to 65°C operating range — a roof cavity in a Mildura February, or a cool store in a Tasmanian winter.
• 400 g and 233 mm long, with the C0203 carrying case included.

Where it earns its keep in Australia

Electrical contractors tracing nuisance safety switch trips in retail, hospitality and residential switchboards — measuring standing leakage before it becomes a callback, and quantifying how close a board is running to its 30 mA limit.

Industrial maintenance teams on VSD-heavy plant, where the filter function separates genuine insulation degradation from the capacitive leakage that drives are supposed to produce.

Solar installers verifying leakage behaviour on grid-connected PV systems, where inverter EMC filters, long DC runs and damp roof penetrations all contribute earth current — and where the difference between a real AS/NZS 5033 insulation problem and normal system leakage needs to be established quickly.

Facility managers and safety officers building a documented leakage baseline across a site, so that next year’s figures mean something. Earth leakage current measurement is also used in in-service testing work under AS/NZS 3760 alongside insulation resistance testing, particularly on equipment where a standard insulation test isn’t appropriate.

TAFEs, RTOs and engineering departments teaching residual current theory with an instrument that demonstrates the concept properly — including why jaw position and external fields matter, using a meter engineered to defeat both.

Choosing between the CM4002, CM4003 and CM4001

The CM4002 and CM4003 share the same sensor, the same six ranges and the same IEC/EN 61557-13 Class 2 compliance. The differences are about where you work:

• CM4002 carries the higher safety rating — CAT IV 300 V and CAT III 600 V conductor-to-ground. If you work at the origin of an installation, at the main switchboard, or on service and metering equipment, this is the model to specify.
• CM4003 trades safety category down to CAT III 300 V but adds an analogue output (RMS and waveform) for feeding a recorder or Memory HiCorder, plus external DC power for unattended recording that outlasts a set of batteries.
• CM4001 is the entry point in the family, with a lower event memory capacity.

For general field work in Australian installations — where a 415 V three-phase system sits at roughly 240 V phase-to-earth, and where you’re regularly working upstream of the main switch — the CM4002’s CAT IV 300 V rating is the sensible default. As always, confirm the measurement category against your own risk assessment and the specific point of the installation you’re working on.

Ready to test out of the box

Every CM4002 ships with the C0203 carrying case, instruction manual, operating precautions and two AA alkaline batteries. Order the CM4002-90 if you want the Z3210 Wireless Adapter bundled from day one — for anyone doing intermittent fault work, it’s the version to get.

We’re a specialist test and measurement supplier, not a general tool shop. That means we can talk you through whether the CM4002 or the CM4003 fits your work, sort out calibration and recertification when it’s due, and keep you supplied with the accessories that actually get used. Got a leakage problem you can’t pin down? Talk to us before you order — we’d rather sell you the right instrument once.

Technical Specifications

Specifications sourced from Hioki CM4002/CM4003 catalogue (rev. CM4002_CM4003E6-3ZE) and the Hioki global product page. Specifications subject to change by the manufacturer.

What is the Hioki CM4002 used for? The Hioki CM4002 is an AC leakage clamp meter used to measure earth leakage current in electrical installations without disconnecting conductors. Electricians clamp it around all live conductors of a circuit at once — active and neutral, or three phases plus neutral — and the meter reads the residual current returning to earth. Its main applications are diagnosing nuisance RCD and safety switch trips, establishing standing leakage baselines during routine inspections, and locating insulation faults in industrial and solar installations.

How does the Hioki CM4002 find the cause of a tripping safety switch? It measures the actual leakage current the RCD is responding to, in milliamps, while the installation stays energised. Because an RCD may operate anywhere between 50% and 100% of its rated residual current, a 30 mA safety switch can trip on as little as 15 mA of accumulated leakage. By clamping progressively downstream through a switchboard, an electrician narrows the leakage to a single final subcircuit. With the optional Z3210 adapter fitted, the CM4002 can also log up to 999 trip events over as long as 30 days, capturing faults that only appear overnight or under specific load conditions.

What is the lowest current the Hioki CM4002 can measure? The CM4002 has a defined accuracy range starting at 0.060 mA, with a best resolution of 0.001 mA on the 6.000 mA range. Its full span extends to 200.0 A across six ranges, so it covers both micro-level leakage detection and ordinary load current measurement.

Is the Hioki CM4002 compliant with IEC 61557-13? Yes. The CM4002 complies with IEC/EN 61557-13 at Class 2, 30 A/m — the international performance standard specifically for leakage current clamp meters. The instrument is also designed to EN 61010 for safety (as a type A current sensor) and EN 61326 for EMC.

What is the difference between the Hioki CM4002 and the CM4003? Both share the same sensor, six ranges and IEC/EN 61557-13 Class 2 compliance. The CM4002 has the higher safety rating at CAT IV 300 V / CAT III 600 V, making it the choice for work at the origin of an installation or on main switchboards. The CM4003 is rated CAT III 300 V but adds an analogue output for RMS and waveform recording, plus an external DC power input for long-duration unattended logging.

Can the Hioki CM4002 measure leakage on solar and VSD installations? Yes, and it includes a specific feature for it. Variable speed drives and PV inverters produce high-frequency capacitive leakage through their EMC filters, which inflates readings on an unfiltered clamp meter. The CM4002’s switchable low-pass filter (−3 dB at 180 Hz ±30 Hz) removes that high-frequency component, so the displayed value reflects the power-frequency leakage that a Type AC or Type A RCD actually responds to.

Does the Hioki CM4002 connect to a phone or tablet? Not on its own. Adding the optional Z3210 Wireless Adapter gives the meter Bluetooth® connectivity to Hioki’s free GENNECT Cross app for iOS and Android. From there you can view live readings, log events, display current harmonics to the 30th order, place readings onto site photographs, generate PDF reports on site, and push values directly into an Excel® file. The CM4002-90 model ships with the Z3210 included.

Does the Hioki CM4002 measure voltage? No. The CM4002 is a dedicated AC leakage current instrument and does not include a voltage measurement function. Electricians typically carry it alongside a multimeter or a multifunction installation tester rather than as a replacement for either.

What size cable does the Hioki CM4002 jaw fit around? The jaws accept conductors up to Ø40 mm in diameter, with internal jaw dimensions of 75 mm × 20 mm. That’s large enough for a three-phase-plus-neutral bundle on a submain, a single large cable, or several smaller circuits clamped together when isolating a fault by elimination.

The post Hioki CM4002 AC Leakage Clamp Meter — Find Nuisance RCD Trips Down to 0.001 mA appeared first on rapid-tech.

The Problem With Most Earth Resistance Testing on Australian Sites

Ask any sparkie who’s spent time doing earthing compliance work what frustrates them most and you’ll hear the same answers: cords that tangle the moment you unwind them, dry soil that means you’re hammering auxiliary rods in again and again just to get a usable reading, and the awkward conversation with a site manager about shutting down power to a server room or hospital wing — just so you can run a standard 3-pole test.

Then there’s the paperwork. Carrying a notebook in the field, scribbling down values, trying to reconstruct a compliant test record later from memory and mud-smeared handwriting. It’s slow, error-prone, and honestly unnecessary with modern equipment.

Earthing system verification is a non-negotiable part of Australian electrical compliance work. Under AS/NZS 3000 (the Wiring Rules), electrical installations must have effective earthing to protect people from electric shock and equipment from fault damage. Soil resistivity surveys are required before grounding system design on commercial and industrial builds. Periodic testing of existing installations is required for ongoing compliance, particularly in facilities covered by AS/NZS 3017. The stakes are real — and your test instrument needs to be up to the job every single time.

The HIOKI FT6041 Earth Tester was engineered to address every one of these pain points directly.

Six Measurement Methods. One Instrument.

Most earth testers on the market do the basics — 3-pole testing, maybe a 2-pole continuity check. The FT6041 goes considerably further, covering the full range of measurement scenarios encountered in real Australian electrical work:

3-Pole Method — The standard fall-of-potential method for precisely measuring ground resistance. Delivers results in just 6 seconds, with accuracy of ±1.5% rdg. ±4 dgt. across the core measurement range. Suitable for general electrical installation testing and compliance verification.

4-Pole Method (Wenner’s Method) — Essential for soil resistivity measurement prior to grounding system design on new construction projects. Geological conditions vary dramatically across Australian regions — sandy coastal soils behave very differently to dense clay or rock formations inland. Getting this right upfront saves time, money, and compliance headaches later.

MEC (Measuring Earth with a Clamp) — HIOKI’s standout capability. The MEC function — Measuring Earth with a Clamp — augments the 3-pole method with a clamp sensor to measure only the current flowing through the specific electrode under test. The result: you can measure earth resistance on live systems without disconnecting a single wire and without shutting down power. For data centres, hospitals, manufacturing facilities, and any other site where power interruption isn’t an option, this is a genuine game-changer.

3-Pole Method with 4-Terminal Measurement — When you’re dealing with very low resistance ground systems — sub-ohm values on bonded structural steel or reinforced concrete installations — this method delivers the precision required.

2-Clamp Method — For multi-point earthing systems where multiple parallel grounds are installed, the 2-clamp method lets you test individual earth electrodes in a network without disconnecting them from the system.

Low-Resistance Measurement — A built-in continuity check function using 4-terminal or 2-terminal measurement, covering ranges from 0.00 Ω to 3000 Ω. Ideal for confirming continuity of bonding conductors immediately after completing ground resistance testing — keeping your workflow tight.

Built to Survive Australian Jobsites

Anyone who’s used an entry-level earth tester in the field knows the anxiety of a $400 instrument sitting in the dirt on a wet construction site or getting covered in red dust on a regional job. The FT6041 is built like it expects to be treated badly.

IP67 Rated for Dust and Water — Completely sealed against dust ingress and protected against immersion in water to 1 metre depth. Mud splatter, rain, puddles — wash it off with water when you’re done. The EN60529-certified IP67 rating covers both the main unit and its sealed connectors.

-25°C to +65°C Operating Range — Australian conditions are extreme in both directions. Whether you’re working through a Queensland summer on an exposed substation site or doing winter commissioning work in alpine Victoria, the FT6041 keeps operating without complaint across its full temperature range.

1-Metre Drop Resistance — With the protector fitted, the FT6041 withstands a 1-metre drop onto concrete. This isn’t a marketing claim — it’s tested to the standard. For an instrument regularly carried up ladders, across scaffolding, and in and out of site vehicles, this matters.

30 V RMS Ground Potential Tolerance — In environments where stray ground potentials are present — near power distribution infrastructure, industrial plant, or high-voltage installations — the FT6041 continues to deliver stable readings with an allowable ground potential of 30.0 V RMS. Live wire warning activates automatically when ground potential is detected.

Designed to Cut Time on Site

Every minute saved on a measurement job is money back in your pocket. The FT6041 has been purpose-designed to eliminate the time-wasters.

Cord Winding That Actually Works — The measurement cables (included 25m yellow, 25m blue, and 50m red cables) are fitted with winders that retract cleanly without tangling or twisting. This sounds like a small thing until you’ve spent 10 minutes straightening knotted cables in a muddy paddock.

100 kΩ Maximum Allowable Electrode Resistance — In dry or rocky Australian soils, getting good auxiliary electrode contact is a persistent challenge. The FT6041’s 100 kΩ maximum allowable resistance for auxiliary grounding electrodes means a single insertion is usually sufficient — no repeated pouring of water around the rods, no repeat insertions trying to hit a usable resistance value.

Earth Nets Module for Concrete Surfaces — Not every measurement location has accessible soil. The included L9846 Earth Nets Module provides a flat-surface electrode alternative for hard-standing concrete areas. Open the module, make contact with the surface, add a splash of water, and take the reading. No drilling required.

6-Second Measurement Time — Full 3-pole measurement in 6 seconds. Combined with auto-hold to capture the reading and continuous measurement mode for monitoring, the FT6041 keeps your workflow moving.

Wireless Data Capture and Reporting

The FT6041 supports the optional HIOKI Z3210 Wireless Adapter (available separately or as part of the FT6041-90 and FT6041-92 KIT variants), enabling Bluetooth connectivity to iOS and Android devices.

Paired with the free GENNECT Cross app, the system allows you to:

• Automatically capture readings when auto-hold activates — no manual transcription
• Attach site photos and handwritten annotations to measurement records
• Overlay measurement values directly on site photographs and drawings
• Export completed reports to Excel for inclusion in compliance documentation packages

For electrical contractors managing compliance documentation under Australian workplace health and safety requirements, this is a significant time-saver and substantially reduces the risk of transcription errors.

Available Model Variants

For most Australian electrical contractors who need the MEC function for live-system testing, the FT6041-91 or FT6041-92 KIT is the recommended configuration.

TECHNICAL SPECIFICATIONS

WHY CHOOSE US FOR YOUR HIOKI FT6041

We supply HIOKI test and measurement instruments with the same level of technical support you’d expect from a specialist calibration and compliance background — not a generic electronics reseller. When you order the FT6041 through us, you’re getting:

• Genuine HIOKI product supplied through authorised Australian distribution channels
• Pre-sales technical advice to ensure you select the right variant (FT6041, -90, -91, or -92 KIT) for your specific application
• NATA-accredited calibration services available if your instrument requires a calibration certificate for compliance documentation
• Fast Australian dispatch — no waiting on international freight for your core test instruments
• Ongoing support from a team that understands Australian electrical compliance requirements, not just the product specs

Query: What is the HIOKI FT6041 used for?

Answer: The HIOKI FT6041 is a professional earth resistance tester used for verifying the safety and compliance of grounding systems in electrical installations. It supports six measurement methods: standard 3-pole ground resistance testing, 4-pole soil resistivity measurement, MEC clamp-on live-system measurement (without disconnecting electrodes), 4-terminal low-value resistance measurement, 2-clamp multi-electrode testing, and low-resistance continuity checks. It is widely used by electrical contractors, facility maintenance teams, and commissioning engineers for compliance work under Australian electrical standards.

Query: Can you test earth resistance without disconnecting the ground wire?

Answer: Yes. The HIOKI FT6041’s MEC (Measuring Earth with a Clamp) function allows earth resistance measurement on live systems without disconnecting any grounding electrodes. A clamp sensor detects only the current flowing through the specific electrode under test, isolating it from other parallel grounds. This capability is essential for testing in facilities such as hospitals, data centres, and industrial plants where power interruption is not possible. The optional FT9847 and CT9848 clamp sensors (included in FT6041-91 and FT6041-92 KIT) are required.

Query: What IP rating does the HIOKI FT6041 have?

Answer: The HIOKI FT6041 Earth Tester carries an IP67 rating to EN60529. This means it is completely protected against dust ingress and can withstand immersion in water to 1 metre depth. It is also rated for operation across a temperature range of -25°C to +65°C and withstands a 1-metre drop onto concrete when the protector is attached — making it suitable for demanding outdoor and construction site use.

Query: What is the difference between the FT6041 and FT6041-91?

Answer: The standard FT6041 includes the main instrument plus a full set of measurement cables, auxiliary earthing rods, the L9846 Earth Nets Module, carrying cases, and batteries. The FT6041-91 includes everything in the standard kit plus the FT9847 Signal Induction Clamp and CT9848 Clamp-On Sensor, which are required to use the MEC (live-system clamp) and 2-clamp measurement functions. The FT6041-92 KIT adds the Z3210 Wireless Adapter to the FT6041-91 configuration for Bluetooth data transfer.

Query: How do you measure soil resistivity with the HIOKI FT6041?

Answer: The HIOKI FT6041 measures soil resistivity using Wenner’s 4-pole method. Four auxiliary electrodes are inserted into the ground at equal spacing, and the instrument injects a test current between the outer two electrodes while measuring the voltage across the inner two. The instrument calculates soil resistivity from these values. This measurement is used during the design phase of grounding systems to determine the electrode configuration required to achieve the target earth resistance, accounting for the specific geological conditions at the site.

The post HIOKI FT6041 Earth Tester | Ground Resistance Meter | Buy Australia appeared first on rapid-tech.