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MI 3125 BT Combo Multifunction Tester

Metrel MI 3125 BT Combo Multifunction Installation Tester is the perfect tester for trainees / apprentices who need an easy-to-use, tough, forgiving machine. Target industries include: Electrical power systems, industrial systems, building‘s facility management, special installations / locations & general purpose system maintenance.

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740.40 incl. VAT)
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  • Competitive quote
  • Expert technical advice/demos
  • Trusted aftercare support




Metrel MI 3125 BT Combo Multifunction Installation Tester

Metrel MI 3125 BT COMBO is the ideal instrument for engineers who perform high volume testing or work regularly on TT and TN systems. Containing all necessary tests for installation safety testing, MI 3125 BT offers the brand new ability to test B-type (DC sensitive) RCDs.


Metrel MI 3125 BT Key Features:

  • Contains integrated characteristics of fuses and RCDs (including EV type) for the evaluation of line/loop impedance results
  • Bright graphic display: the backlight ensures that results, indications, measurement parameters and messages are clear, visible and easy to read
  • Clear PASS/FAIL: the red and green LEDs on either side of the display provide a clear PASS/FAIL evaluation of test results
    • Each test has its own individual help screen describing how to connect the instrument into the installation and how to perform a measurement
    • All the results can be quickly saved and referenced on the instrument and then downloaded via the MESM software.
  • Help screens: instrument comes complete with built-in help screens for referencing on site
  • Earth resistance measurement: instrument performs 3-wire earth resistance testing with two additional rods
  • Built-in fuse tables: this unique feature allows automatic evaluation of the line / loop impedance compared to the regulations
  • Online voltage monitoring: monitors all 3 voltages in real-time
  • Upgradeable: if changes occur to the regulations, upgrades can be made to the firmware to keep the instrument up to date
  • Polarity swap: automatic polarity reversal on continuity test
  • Insulation range: wide range of insulation test voltages from 50 V to 1000 V, reading up to 1000 MΩ
  • Trip Lock function: Zs (RCD) function performs a loop impedance test without tripping the RCD
  • Multi-system testing: tests on single and multiphase TT and TN systems
  • Built-in charger and rechargeable batteries: unit has a built-in charging circuit and comes complete with a set of rechargeable NiMH batteries
  • RCD auto: automated RCD testing procedure significantly reduces test time
  • B type RCD testing: is supported
  • BT connectivity: it enables BT communication with Android tablets and smart phones via built-in BT
  • PC SW Eurolink PRO: included in the standard set enables downloading of test results and parameters and creation of test reports


Metrel MI 3125 BT Measuring Functions:

  • Insulation resistance with DC voltage
  • Continuity of PE conductors with 200 mA test current with polarity change
  • Continuity of PE conductors with 7 mA test current (continuous measurement) without RCD tripping
  • Line impedance
  • Loop impedance
  • Loop impedance with Trip Lock RCD function
  • TRMS voltage and frequency
  • Phase sequence
  • RCD testing (general and selective, type AC, A and B)
  • Earth resistance (3-wire method)


What comes with the Metrel MI 3125 BT?

  • Instrument MI 3125BT COMBO PRO
  • Soft hand strap
  • Small soft carrying bag
  • Test lead, 3 x 1.5 m
  • Mains Plug Lead
  • Tip Commander, 1.5m
  • Test probe, 3 pcs (blue, brown, green)
  • Crocodile clip, 3 pcs (blue, brown, green)
  • Power supply adapter + 6 rechargeable batteries NiMH, type AA
  • USB cable
  • Metrel ES Manager BASIC license
  • Metrel aMESM PRO Android app
  • Short instruction manual
  • Calibration certificate


Metrel MI 3125 BT related product:



Comparison Chart for: Metrel MI 3125 BT Combo Multifunction Tester

MI 3125 BTMI 3100 SEMI 3152MI 3155
Screen type
Monochrome dot matrix
Full colour dot matrix
Touch screen
Instrument control
Rotary switch
Push keys
3-wire Trip-Lock RCD function, with no reported RCD uplift
Hi current loop test for L-L and L-N testing and where there is no RCD
PFC and PSCC displayed with loop impedance
Operating frequency45Hz to 65Hz45Hz to 65Hz45Hz to 65Hz14Hz to 500 Hz
Earth loop impedance ranges
3-wire loop test
Fuse tables on-board for instant pass or fail
Z auto func., Ze, Zs, PFC, PSCC and touch voltage with the single press of test button
Ultra-low current test for vehicle charge point testing
Supports Hi resolution testing with A 1143 adapter
4-wire loop test for result close to the source of supply
50V, 100 V, 250 V, 500 V and 1 kV test voltages
2.5 kV test voltage
Applied voltage display
Insulation test ranges
Pass of fail against pre-set limits
AUTO L-PE, N-PE and L-N testing
Surge protection or varistor testing
Diagnostic tests PI and DAR
AC RCD rating 10 mA, 30 mA, 100 mA, 300 mA, 500 mA and 1000 mA
RCD Type A, Type AC, Type F
RCD Type B and Type B+ - pure DC
Standard or time delayed
RCD testing ranges
Portable RCDs type PRCD, PRCD-2P, PRCD-3P, PRCD- S, PRCD- S+ & PRCD- K
EV RCM / EV RCD 30 mA AC and 6 mA DC*
Phase or polarity0 / 1800 / 1800 / 1800 / 180
½I, I and 5I tests
Ramp test for RCD fault finding
Continuity and low R range
Auto RCD test for trip time and trip current displayed on a single screen, no scrolling
7 mA test current for continuity check through RCD & prolonged battery life
Adjustable Pass/ fail indicator light limits
Adjustable buzzer threshold
Pre programmed
User programmable
Testing TN and TT earthing systems
Testing IT, floating earth systems
Voltage, frequency and phase rotation range
0 V to 550 V AC resolution 1V
Single-phase TN/ TT systems displays L-N, L-PE , N-PE in single screen
3-phase TN/ TT systems displays L1-L2, L1-L3 , L2-L3 in single screen
True RMS measurement
Frequency0Hz to 500 Hz0Hz to 500 Hz0Hz to 500 Hz0Hz to 500 Hz
Phase rotation
Voltage Drop measurement
Power quality range
Active power (P), Apparent power (S) and Reactive power (Q)
Power factor, Total harmonic distortion (THD)
Voltage harmonics and THD
Current harmonics and THD
Earth electrode resistance range
3-wire technique
Selective method with 3-wires and clamp*
4-wire earth resistivity*
2 clamps contactless method*
Earth test set supplied
Active safety system
Auto-test inhibit
Auto- discharge
Auto PE test
Touch voltage monitoring
Results handling / on-board memory
On-board memory size3 levels / 1700 locations3 levels / 1700 locations8 GB8 GB
Memory management
Workspace manager
Full keyboard for labelling files and results in plain English
USB, RS232 and bluetooth® connectivityOptional accessory
QR and, or barcode scanner support*
FREE Electrical Safety Management Basic software license
Other benefits
Rechargeable batteries with on-board recharging
TRMS leakage and load measurement*
Illuminance measurement*
Cable tracing*
Insulation monitoring device testing - IT systems
First fault leakage current measurement - IT systems
Records visual inspection
Full set of test, download and recharge leads
Soft test and carry bag
Firmware user updatable for product’s lifetime
Safety ratingCAT IV 300 VCAT IV 300 VCAT IV 300 VCAT IV 300 V
* Tester enabled but optional accessories required


Accessory Code Description Price (Ex VAT)
A1003 Mains Plug £51.72 ADD
A1013 Crocodile Clip Black £7.95 ADD
A1015 Test Probe Blue £6.89 ADD
A1062 Test Probe Green £6.89 ADD
A1153 20 m Test Lead Black £49.82 ADD
A1154 4 m Test Lead Black £26.50 ADD
A1160 6 Cell AA battery charger £146.28 ADD
A1164 50 m Test Lead Black £79.50 ADD
A1169 Fast charger for 12AA/ 6 C Type £305.28 ADD
A1271 Soft carrying bag with shoulder strap £60.42 ADD
A1297 Crocodile Clip Brown £7.95 ADD
A1298 Test Probe Brown £6.89 ADD
A1310 Crocodile Clip (Blue) £7.95 ADD
A1296 Test Leads (Brown; Green; Blue) £46.64 ADD
CS2099 Eurocheck Field Calibrator £307.40 ADD