Earth test equipment specialists

Mitton Instruments specialises in manufacturing earth grid test equipment. Our equipment has been developed after many years of practical investigation and testing.

Our specialist equipment is designed for ease of use and understanding, robustness and above all, to work in the demanding environment of high voltage transmission and distribution systems.

earth grid test equipment


The ET1000 is a versatile 4-terminal earth tester suitable for the measurement of soil resistivity, earth electrode or grid resistance, conductor/joint resistance and primary plant bonding resistance.

The ET1000 is especially suited to soil resistivity measurements due to its multi-function, high resolution, high noise rejection and high voltage output feature (which is used to overcome high current electrode contact resistance in sandy or stony soils).

  • Range: 5 µΩ – 19.99 kΩ
  • Input impedance: 2 MΩ/220 kΩ
  • Output current: 65 mA/10 mA at 48 Vp/400 Vp
  • Micro-ohms: 1A output
  • Battery life approx 12 hrs
  • Test mode reversing dc
  • Dimensions: 270 x 240 x 125 mm
  • Weight: 1 kg

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Single Wire Earth Return Systems tester.

The ST1000 is designed to measure the earth electrode resistance of Single Wire Earth Return Systems. It uses the SWER transformer (isolation or distribution) load currents to provide the measurement signals and accepts two CT inputs and one voltage input.

Testing can be carried out with the SWER in service and no disconnection of earth electrodes is required.

  • Range: 10 mΩ – 1,999 Ω
  • Input voltage: 0 – 300 Vrms
  • Current inputs voltage range 3 Vrms
  • SLA battery
  • Dimensions: 270 x 240 x 125 mm
  • Weight: 1 kg

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M1000 Micro-Ohmmeter

The M1000 micro-ohmmeter is 4-terminal instrument designed primarily for switchyard use and features portability and high noise rejection.

Measurement of plant bonding and earthing conductor integrity can be carried out without de-energising the equipment. Low test current allows the use of long test cables to reach equipment.

  • Range: 0 µΩ – 200 Ω
  • Test current: 1 A max
  • Li-ion battery
  • Weight: 1 kg
  • Dimensions: 270 mm x 240 mm x 125 mm

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The Ultrahound is a highly directional and sensitive partial discharge/arc and corona detector. Electric discharges in air emit broad spectrum noise and using ultrasonic techniques the source of any discharge can be traced.

Electric discharging of outdoor power line components can cause radio and TV frequency interference or indicate possible future failure of equipment. The Ultrahound can be used from up to 30 m from the noise source. A separate short range direction wand is used for close inspection.

The Ultrahound may be used for a variety of situations, including:

  • Power line discharge & corona such as cracked insulators or bushings, faulty cable termination or damaged line hardware.
  • Partial discharge of equipment (e.g. power cables, bushings, generator housing) under HV test (laboratory or in the field).
  • Frequency Response: 37 – 43 kHz, with excellent out of band rejection
  • Highly directional dish enables accurate pin pointing of faults
  • Battery Powered (4 x AA)
  • Includes self test device for checking and training

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The LCI2000C injects a constant current into the earth grid. The test frequency is variable from 45 Hz to 65 Hz, in 1 Hz steps. This provides a unique test condition and the signal can be easily identified when combined with the TVM1100 Tuned Voltmeter. The earth grid characteristics including impedance, touch, transferred, step voltages and current splits can be determined.

An optional stepdown transformer is available to achieve test current.

Auto shut-off is a safety feature that ensures the injected current ceases should the injection circuit be interrupted.

The LCI2000C output is galvanically isolated from the input supply. All functions can be controlled via an integrated front panel.

See the equipment featured in T&D World

  • Input voltage range 100 Vac – 250 Vac
  • Output current 0.5 – 10A
  • Load Loop Impedance: 4 Ω – 150 Ω
  • Output voltage up to 220 Vac
  • Output power: 2,200 VA max
  • Output frequency 45 – 65 Hz
  • Optional GPS sync for current split phase measurements
  • Weight: 9 kg
  • Dimensions: 370 x 190 x 190 mm

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The TVM1100 is designed for use with the LCI2000C injection unit to detect the voltages generated by the injected current. Due to its excellent noise rejection very low levels of test voltage may be identified, even where the background noise levels is high. Such noise may result from residual voltage on the earth grid, electric field coupling or induction into test cables.

The TVM1100 has a high input impedance to ensure accurate reading of prospective touch, step and transferred voltages. It also has a switchable low input impedance (1 kΩ) to simulate a person’s body impedance. The TVM1100 includes a second input for a flexible or clamp CT to enable current splits and associated phase angles to be measured, as well as GPS tracking and data logging. The GPS facility is ideal for the earth potential rise traverse while the data logging enables any readings to be recorded.

  • Channel 1: 0 – 6.000 V; 0 – 60.00 V; 0 – 300.0 V (auto-ranging)
  • Channel 2: 0 – 3 V
  • Phase angle: ± 180°
  • Accuracy: 1% ± 2 counts
  • Frequency: 45 Hz – 65 Hz ± 1 Hz (in 1 Hz steps)
  • Input impedance: 2 MΩ /1 kΩ



We are currently unable to accept new customers.


We are currently unable to accept new customers.