Checking that the protective devices of a low-voltage installation clear a short circuit in time means measuring the fault loop impedance and knowing the prospective short-circuit current, ideally without taking the installation out of service. The AMZC-304 measures ZL-PE, ZL-N and ZL-L from 0.13 to 1999 Ω per EN 61557 with 0.01 Ω resolution and ±(5% m.v. + 3 digits), calculates the prospective short-circuit current up to 40.0 kA, measures without tripping RCDs of 30 mA or more from 0.5 Ω and verifies protective conductor continuity with ±200 mA, in an IP67 housing that stores 990 results and sends them over Bluetooth.
AMZC-304 key data
- Loop impedance: ZL-PE, ZL-N and ZL-L from 0.13 to 1999 Ω per EN 61557 (1.2 m leads), 0.01 Ω resolution and ±(5% m.v. + 3 digits), with the RS and XS components.
- Measuring current: the AMZC-304 drives a maximum of 7.6 A at 230 V and 13.3 A at 400 V, in three 10 ms pulses.
- No RCD tripping: ZL-PE from 0.5 Ω in circuits with RCDs of IΔn ≥ 30 mA, in the 180 to 270 V range, with accuracy from ±(6% m.v. + 5 digits).
- Short-circuit current: calculated from the impedance and the rated voltage and displayed from 0.110 A to 40.0 kA (up to 24.0 kA in no-trip mode).
- Continuity: protective and equipotential conductors with ±200 mA per EN 61557-4, from 0.12 to 400 Ω with ±(2% m.v. + 3 digits); low-current resistance up to 1999 Ω.
- Networks: 220/380, 230/400 and 240/415 V, with an operating range of 180 to 270 V (ZL-PE, ZL-N) and 180 to 460 V (ZL-L), 45 to 65 Hz; voltmeter from 0 to 500 V.
- Memory and communication: the AMZC-304 stores 990 results and transfers them to the PC over Bluetooth.
- Ruggedness: IP67 housing, CAT IV 300 V (CAT III 600 V) with double insulation, four AA batteries or NiMH accumulators and operation from 0 to +50 °C.
Advantages
Loop with 0.01 Ω resolution
The standard-current 2p measurement covers 0.13 to 1999 Ω per EN 61557 with ±(5% m.v. + 3 digits), using up to 13.3 A at 400 V (7.6 A at 230 V) in three 10 ms periods.
Without tripping RCDs
The low-current mode measures ZL-PE from 0.5 Ω in circuits protected by RCDs of 30 mA or more, with the installation in service and no outages.
Fault current at a glance
From the impedance and the rated voltage, the meter calculates the prospective short-circuit current from 0.110 A to 40.0 kA and separates the resistance RS and reactance XS components.
Continuity per EN 61557-4
Protective and equipotential connections are verified with a ±200 mA current from 0.12 to 400 Ω, and resistance with low current up to 1999 Ω.
Applications
- Verification of short-circuit protection in residential and office buildings.
- Industrial plants with fault currents up to 4.4 kA.
- Circuits protected by RCDs, measured without causing trips.
- Continuity checks of protective and equipotential conductors.
About the product
The AMZC-304 is one of the most compact loop meters in its class: 220 × 102 × 61 mm and about 0.8 kg, powered by four AA batteries or NiMH accumulators. It works in 220/380 V, 230/400 V and 240/415 V networks (180…460 V range) at 45…65 Hz, measures voltage from 0 to 500 V and frequency, and supports measurement with the L and N conductors swapped.
It complies with the EN 61557 series and the CAT IV 300 V (CAT III 600 V) category with double insulation. The 990-result memory downloads to the computer over Bluetooth, where the reader software archives and documents the verifications; the WS-05 UNI-Schuko adapter speeds up measurements at socket outlets.
Available accessories: WS-05 adapter with angular UNI-Schuko plug, 1.2 m test leads (red, blue and yellow), pin probes, crocodile clip, carrying case, straps, batteries and a factory calibration certificate; optionally the WS-03, WS-04 and WS-07 adapters, AGT three-phase adapters from 16 to 63 A and 5, 10 and 20 m leads.
Technical specifications
| Loop impedance | 0.13…1999 Ω per EN 61557; resolution from 0.01 Ω |
| No-trip mode (RCD) | From 0.5 Ω in circuits with RCDs ≥30 mA |
| Measuring current | Max. 13.3 A at 400 V; 7.6 A at 230 V (3 × 10 ms) |
| Short-circuit current | Calculated: 0.110 A…40.0 kA; RS and XS components |
| Continuity | ±200 mA per EN 61557-4; 0.12…400 Ω |
| Voltage and frequency | 0…500 V; 45.0…65.0 Hz |
| Memory and interface | 990 results; Bluetooth |
| Safety | CAT IV 300 V (CAT III 600 V); IP67 |
| Loop accuracy | ±(5% m.v. + 3 digits); no-trip mode from ±(6% m.v. + 5 digits) |
| Operating range | 180…270 V (ZL-PE, ZL-N); 180…460 V (ZL-L) |
| Power supply and environment | 4 AA batteries or NiMH accumulators; 0…+50 °C |
Frequently asked questions
How accurate is the AMZC-304 and what current does it use to measure the loop?
With standard current the AMZC-304 measures from 0.13 to 1999 Ω per EN 61557 with 0.01 Ω resolution and ±(5% m.v. + 3 digits), driving a maximum of 7.6 A at 230 V or 13.3 A at 400 V in three 10 ms pulses. In no-trip RCD mode it measures from 0.5 Ω with accuracy from ±(6% m.v. + 5 digits).
Can it measure with long leads or with a socket adapter?
Yes. The AMZC-304 range per EN 61557 starts at 0.13 Ω with the 1.2 m leads, 0.17 Ω with 5 m, 0.21 Ω with 10 m, 0.29 Ω with 20 m and 0.19 Ω with the WS-01, WS-05 and WS-07 adapters, always up to 1999 Ω.
Which networks can it measure in?
In 220/380 V, 230/400 V and 240/415 V networks with working voltages from 180 to 460 V and a frequency of 45 to 65 Hz.
Does it trip RCDs while measuring?
Not in RCD mode: the low-current measurement avoids tripping RCDs of 30 mA or more, keeping the installation in service.
Does it calculate the prospective short-circuit current?
Yes. From the measured impedance and the rated voltage it indicates 0.110 A to 40.0 kA, with the resistance and reactance components.
Does it withstand site conditions?
Yes. The sealed IP67 housing, backlit keyboard and AA battery power make it fit for outdoor and harsh environments.
