• Megger

Megger® BMM501, BMM502 & BMM503

Insulation & Continuity Testers

Megger BMM80 Insulation & continuity testers


  • Options of 250 V, 500 V, 1000 V insulation ranges
  • 200 mA continuity range
  • Instant response “ZAP” buzzer
  • Voltage measurement to 600 V
  • MEGGER Intelligent Safety System
  • Patented backlit display
  • K Ohms range for servicing
  • Probe support for other measurements
  • Waterproof and Dustproof to IP54
  • Complies with the requirements of BS 7671 16th Edition, and EN61557


The MEGGER® BMM503 Insulation and Continuity tester provides all the necessary features for electrical installation testing and servicing needs. The instrument is microprocessor controlled to ensure outstanding performance with ease of use. For ultimate reliability, the BMM503 is waterproof and dustproof to IP54 and is supplied with a 3-year warranty.

The BMM500 series has been carefully designed to maximise features which are of real benefit to the electrical contractor or service engineer competing for business in today’s market.

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Intelligent Safety System (ISS):

With increased pressure of time to complete jobs it is inevitable that whilst performing tests on an electrical system mistakes will occasionally be made exposing the user to danger or under certain circumstances damaging the instrument. The BMM500 series incorporates Megger’s Intelligent Safety System which has been designed to ensure that such mistakes don’t become disasters.The ISS consists of:

A hands free 200 mA continuity test range meeting the
requirements of European legislation is also included to
ensure the accurate measurement of ring circuit final
conductors and primary and supplementary bonding. The
range has a facility to null the resistance of the test leads
ensuring that the measurement displayed is due entirely to
the conductors under test. A continuity buzzer is
incorporated and sounds when resistance’s below
approximately 5 Ω are encountered

  • Live Circuit Warning:

    Warns of accidental connection to a live circuit greater than 25 V on any range.

  • Safe Contact Detector:

    Prevents danger during continuity testing if contact is made with a live circuit and minimises the chances of blowing the instruments fuse.

  • Test Lockout:

    Prevents test being energised in presence of external voltages.

  • Default Voltmeter:

    Displays presence of dangerous voltages on connected circuit irrespective of instrument range selected.

  • Auto Discharge:

    Safely discharges connected circuits after insulation test. Instant Response “ZAP” Buzzer. The audible buzzer range is frequently used for checking for correct polarity in installed circuits and for point to point connectivity in servicing. It is vital that the instrument provides an instant response in such situations. Many insulation testers take up to 1 second to respond making them highly tedious and frustrating in use. The BMM500 series features specially designed “instant response” circuitry some 80 times faster than rival products, making the instrument a pleasure to use. The “Zap” Buzzer also features seven user selectable thresholds below which the buzzer will sound continuously. At values above the chosen limit the buzzer will sound an intermittent tone unless the value is above 3 kΩ in which case no sound will be emitted. This provides a useful audible approximation of the value being measured.

  • D.A.R.T. Display:

    The BM500 series incorporates a large backlit digital LCD display combining Digital and Analog Response Technology. The patented design provides the benefits of true analog clarity, (with its ability to spot an momentary insulation breakdown or poor continuity connection), with the stability and simplicity of a digital reading. The display is backlit enabling use in dimly lit areas, which is especially useful when the installation power is turned off for testing.

  • Insulation Testing:

    Instruments are available with either one, two or three insulation test voltages to suit all needs.BM503 = 250 V, 500 V, 1000 V BM502 = 500 V, 1000 V BM501 = 500 V Whichever model is chosen the ranges are capable of supplying 1mA test current at the minimum pass levels expressed by 16th Edition Wiring Regulations, (BS7671), IEC364, HD384 and VDE0413 Parts 1 and 4.

  • Continuity Testing:

    A hands free 200 mA continuity test range meeting the requirements of UK and European legislation is also included to ensure the accurate measurement of circuit final conductors and primary and supplementary bonding.

  • Test Lead Zeroing:

    The continuity range has a facility to automatically remove the resistance of the test leads from the measured value, a task that would normally have to be done manually. This ensures that the measurement displayed is due entirely to the conductors under test. The insulation and continuity ranges are augmented by a number of additional measurement ranges such as autoranging voltage measurement up to 600 V ac/dc, and Kilohms resistance measurement enabling component diagnostic measurements during servicing. Current may be measured by connection of an external mV output clamp such as the optional Megger MCC10.

  • Pouch:

    The BMM500 series has been designed to withstand the day to day handling and storage of a tool bag environment and also comes complete with durable carry pouch with provision for storage of all leads.

  • Additional Servicing Measurements:

    The BMM500 series supports the connection of virtually any mV probe. Such devices extend the range of possible measurements almost endlessly including such items as temperature probes, air speed indicators and high current clampmeters such as used in heating and ventilation (HVAC), and servicing.

  • Literature
  • Specifications
Insulation Ranges
Test Voltages : 250, 500, 1000 V
Measuring Range:
1000 V 0,01 MΩ to 10,000 MΩ
500 V 0,01 MΩ to 5,000 MΩ
250 V 0,01 MΩ to 2,000 MΩ
Test voltage accuracy: +15% maximum on open circuit
Test Current on load:

1mA at min. pass value of
insulation specified in BS7671,
HD384 and IEC 364, 2 mA max.

1000 V ±0,2% per 1000 MΩ, ±2% ±2 digits
500 V ±0,4% per 1000 MΩ, ±2% ±2 digits
250 V ±0,8% per 1000 MΩ, ±2% ±2 digits
Measuring Range: 0,01 Ω to 99,9 Ω (0 to 10 Ω on
analog scale)
±2% ±2 digits
Open circuit voltage: 5 V ±1V
Test current: 210 mA ±10 mA (0 – 2 Ω)
“Zap” Buzzer: Operates continuously at less than
selected limit or intermittent tone
above limit but below 3 kΩ.
(Silent above 3 kΩ)
Silent buzzer mode: Replaces audible tone with visual
indication on display when
measured value below selected
Measuring Range: 0,01 kΩ to 9,99 MΩ (0 to 100 MΩ on analog scale)
with Auto Ranging or Range Lock
Accuracy: ± 3% ± 2 digits
Open circuit voltage: 5 V ±1V
Short circuit current 25 μA ± 5 μA
Measuring Range: ±1V to ±600 V (0 to 1000 V on
analog scale)
Accuracy: 0 to 600 V d.c. or a.c. (50/60 Hz)
±2% ±3 digit0 to 600 V a.c. (400 Hz)
±5% ±3 digits
Measuring Range: ±0,1 mV to 1 ±999 mV(0 to 1000 mV on analog scale)
Accuracy: 0,1 mV to 10 mV d.c./ a.c.
(50/60 Hz)
±2% ±5 digits10mV to 1999mV d.c./a.c.
±2% ±3 digits0,1 mV to 10 mV a.c. (16-460 Hz)

±5% ±7 digits

10 mV to 1999 mV a.c. (16-460 Hz)

±5% ±3 digits

Probe Compatibility
Virtually any mV output probe may be connected to facilitate
measurements of other parameters such as temperature, humidity
etc. A unique probe offset adjustment facility is included.
Battery Type:: 6 x 1,5 V Alkaline cells IEC LR6 type
Battery Life: Typically 3000, 5 second 1 kV tests
Backlight User selectable LED backlight with auto turn off to save battery