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ETCR · ETCR6920B Flexible Rogowski Coil Clamp Multimeter 0-10000A Φ300mm
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A flexible Rogowski coil instrument measuring AC current from 0 mA to 10,000 A through a 300 mm insulated loop, with AC voltage to 750 V, DC voltage to 1000 V, resistance to 2 kilohms and continuity, a multi parameter display, 600 stored readings over USB, and a mass of 266 g. The coil is a genuine capability that a rigid clamp cannot match. The listing publishes no measurement category rating, which on an instrument offering 1000 V is the thing to resolve before buying.
What the coil buys you
A conventional clamp meter works by closing a magnetic core around a conductor. That design is excellent and it has two structural limits: the core saturates as current rises, and the jaw has to physically open wide enough to go round the thing you are measuring.
A Rogowski coil removes both. It is a flexible winding with no iron in it, measuring the rate of change of the magnetic field around a conductor and integrating that to a current. With no core there is nothing to saturate, so the top of the range can be enormous, and because the coil is just an insulated cable it can be threaded into places a jaw cannot reach and then clipped into a loop.
That is why the specifications look improbable together: 10,000 A on an instrument weighing 266 g with a 300 mm loop. A rigid clamp built for that current would be a two handed object.
The practical cases are specific. A busbar in a distribution board, flat and wide, where no jaw closes. Four parallel cables feeding one large load, which you want to measure as a single current rather than four. A conductor in a crowded panel with no clearance to swing a clamp into position. In each of those the coil is not a convenience, it is the only way to take the reading. Our clamp meter comparison covers where rigid jaws remain the better choice.
It cannot measure DC current, and that is physics
Read the first bullet carefully and the asymmetry is there: AC current from 0 mA to 10,000 A, AC and DC voltage up to 750 V AC and 1000 V DC.
Current is AC only. Voltage is both. That is not an omission or a cheaper variant, it follows directly from how the coil works. A Rogowski coil produces a voltage proportional to the rate of change of current. A steady direct current has no rate of change, so the coil output is zero regardless of how many amps are flowing.
This matters because DC current measurement is exactly what a growing share of electrical work needs: solar arrays, battery systems, vehicle charging infrastructure, anything with a DC bus. For all of that you need a Hall effect clamp, and no flexible coil of this type will do it.
So the instrument is honest, but the honesty is easy to miss in a bullet that leads with versatile multifunction tool. If DC current is on your list, stop here.
The missing safety rating
| Specification | Published in the listing |
|---|---|
| AC current | 0 mA to 10,000 A |
| DC current | Not supported, inherent to the coil type |
| AC voltage | Up to 750 V |
| DC voltage | Up to 1000 V |
| Resistance | 0 to 2 kilohms, plus continuity |
| Coil | Flexible, fully insulated, 300 mm, 11.8 inch |
| Display | Multiple parameters simultaneously |
| Memory | 600 readings, USB transfer, 1.8 m cable supplied |
| Mass | 266 g, tool bag included |
| Measurement category rating | Not stated in the listing bullets |
| Measurement accuracy | Not stated in the listing bullets |
| Frequency range | Not stated in the listing bullets |
| True RMS | Not stated in the listing bullets |
The missing measurement category is the one to act on. CAT II, III and IV describe where on an electrical system an instrument is built to be used, and they exist because a fault upstream produces transient voltages far above the nominal figure. A meter rated CAT III 600 V is designed to survive those transients at a distribution board. A meter with no rating has made no such claim.
An instrument offering 1000 V DC and 750 V AC measurement invites use on exactly the systems where category matters most. The listing describes the coil as fully insulated and the design as safe, but safe is not a rating and insulation is not a transient withstand figure. Establish the category before using this anywhere beyond a final circuit.
Two further absences shape what the readings are worth. There is no accuracy figure, so a current value has no stated tolerance. And there is no true RMS claim and no frequency range, which matters because a Rogowski coil integrating a distorted waveform on a drive circuit will read quite differently depending on how the electronics handle it.
Who should buy it
Buy this for the coil. If your work involves busbars, parallel cable sets, crowded panels or currents beyond what a hand held jaw will take, a flexible coil instrument at this weight is a real capability and the 600 reading memory with USB transfer makes it a documentation tool as well.
Do not buy it for DC current, which it cannot do by design. Do not buy it as a general purpose multimeter, since resistance stops at 2 kilohms. And do not take it onto a distribution system on the strength of its voltage range alone, because the measurement category that would justify that is not published. Resolve that with the seller first, and treat the absence as a reason for caution rather than an oversight.
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Products shown because their documented specifications fit this guide. Price and availability are on Amazon and can change.
Frequently Asked Questions
Why can a flexible coil read 10,000 A when a normal clamp cannot?
Because it does not need an iron core. A conventional clamp meter closes a magnetic core around the conductor, and that core saturates at high current and has to be physically big to handle a lot of it. A Rogowski coil is a flexible air cored winding that measures the rate of change of the magnetic field instead, so it does not saturate the same way and it can be made long and thin. That is how a 266 g instrument with a 300 mm loop reads to 10,000 A.
Can it measure DC current?
No, and this is inherent rather than a cost saving. A Rogowski coil responds to a changing magnetic field, so a steady direct current produces no signal at all. The listing is consistent with this: it states AC current from 0 mA to 10,000 A, while voltage is given for both AC and DC. If you need DC current, this is the wrong instrument type, not just the wrong model.
What does the absent CAT rating mean?
It is the most important gap here. The measurement category rating, CAT II, III or IV, describes how much transient energy an instrument is built to survive at a given voltage, and it exists because a fault on a distribution system produces spikes far above the nominal voltage. This listing offers 1000 V DC and 750 V AC measurement with no category and no voltage withstand figure. Do not assume it is suitable for distribution panel work on the strength of its voltage range.
Where is a 300 mm coil genuinely better?
Around things a rigid jaw cannot close on: a busbar, a bundle of parallel cables feeding one load, a conductor you cannot get square access to, or a cable in a crowded panel where there is no room to swing a clamp. The coil is flexible and fully insulated per the listing, so it threads where a jaw will not go.
Is 600 stored readings useful?
It is a record rather than a logger. The listing states 600 stored readings transferred over a 1.8 m USB cable for analysis, saving or printing. That suits recording a set of measurements across a panel and producing a document afterwards. It is not continuous logging and the listing does not claim an interval or a timestamp.
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