Short circuit loop impedance meter MZC-304F

MZC-304F short circuit loop impedance meter

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Sonel MZC-304F compact short circuit loop impedance meter with many measurement functions (replaces the MZC-304).

The presented model is one of the smallest instruments available on the market intended for short circuit loop impedance measurements in 230/400 V networks and continuity of protective and equipotential connections measurements. The MZC-304F meter performs short circuit loop measurements with a resolution of 0.01 Ω, also in the case of measurements in networks protected with RCD switches. With a backlit keyboard and display, the device can be used even in low light. The device has a sealed casing with IP67 protection, which is characterised by excellent resistance and ensures smooth operation even under adverse environmental conditions.

The device meets the requirements set out in standard EN 61557.


  • Fault loop impedance measurement with 0.01 Ω resolution.
  • Low-current impedance measurement in circuits protected by RCD ≥ 30mA with 0.01 Ω resolution (range of 180…270 V)
  • Operates in networks with voltages 220/380 V, 230 V/400 V, 240/415 V (operating range 180…460 V)
  • Operating voltage range: 180…270 V (for ZL-PE and ZL-N) and 180…460 V (for ZL-L).
  • Maximum measuring current: 7.6 A for 230 V (3×10 ms), 13.3 A for 400 V (3×10 ms).
  • Operating frequency 45…65 Hz
  • Calculation of Ik fault current.
  • Measurement with swapped L and N conductors.
  • Measurement of resistance (RS) and reactance (XS) components.
  • Low-voltage measurement of continuity of circuit and resistance.

Additional features

  • Contact electrode – quick testing of proper connection of PE conductor.
  • Voltage measurement 0…500 V.
  • Frequency measurement 45.0…65.0 Hz.
  • Memory of 990 measurement results, ability to transfer the data to a PC via Bluetooth.
  • Power supply: batteries (4 x LR14) or rechargeable batteries (4 x NiMH).


The instrument is dedicated to personnel performing measurements in single and multi-family buildings, office buildings, industrial plants and any other places equipped with low voltage electrical systems. In addition, the meter is intended for maintenance personnel working on objects, where fault currents reach 4.4 kA (measured according to EN 61557). MZC-304F is also a great tool for checking circuits additionally protected by residual current devices.