• Megger

Megger® BM400/2 Series

Insulation Continuity Testers


  • Analog and Digital display of data
  • Fully complies with the requirements of BS 7671, HD 384 and IEC 364
  • 1 mA insulation output current n 200 mA short circuit current output
  • Remote control switched probe
  • Optional RS232 port
  • Optional current clamp accessory
  • Waterproof and dustproof to IP54


The Megger BM400/2 Series of autoranging insulation and continuity testers, provides simplicity of use in a hand-held instrument designed to IEC1010-1 safety standards. The BM400/2 Series offers a range of single, dual and multi-voltage variants to fit specific applications. The insulation ranges output the nominal test voltage when loaded with 1 mA as specified within these standards. The continuity ranges have a short circuit test current of at least 200 mA. In addition to the insulation and continuity ranges, the BM400/2 series has a resistance range and 2 voltage ranges. The resistance range measures up to 100k ohm on the digital scale and up to 10 M ohm on the analog scale. Due to the low test voltage and current of this range, the instruments can be used to test circuits with sensitive equipment connected, without causing damage.

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Extensive use by electrical contractors

The BM400/2 series, designed for flexibility and versatility, has a wide variety of applications and is ideal for testing electrical installations to the British and International Wiring Regulations. Each instrument in the series conforms to the requirements of Table 71 A in BS 7671, and to VDE 0413 parts 1 and 4, HD384 and IEC364.

The BM400/2 series can be used in both the domestic and industrial contracting environments. Test voltages of 250 V, 500 V and 1000 V d.c. are available. A 250 V insulation test voltage is necessary to test low voltage circuits supplied by an isolating transformer. 500 V d.c. is the most commonly required voltage, since it is used to test all circuits except low voltage circuits with a nominal voltage up to and including 500 V. The 1000 V d.c. test voltage is used on circuits with a nominal voltage greater than 500 V and less than 1000 V.>/p>

The continuity ranges can be used to test the continuity of protective and ring final circuit conductors, and the polarity of the conductors.

The BM400/2 series instruments can also be used for insulation and continuity tests on transformers, motors, generators, domestic appliances, power tools, such as electric drills, and many other pieces of electrical equipment.

On high energy systems it is essential to use test leads with fused prods when measuring voltage. These are available as an optional accessory.

  • Literature
  • Specifications
pdf icon Description
++ BM400 Specification sheet
Insulation Ranges
BM400/2 500 V, 1000 V
BM401/2 500 V
BM402/2 500 V, 1000 V
BM403/2 250, 500 V, 1000 V
BM404/2 500 V
Measuring Range:
0,01 – 999 MΩ on all ranges (0 – 10 GΩ on analog scale)
Measuring Range: 0,01 – 99,9 Ω (0-50 Ω on analog scale)
±2% ±2 digits
Open circuit voltage: 5 V ±1V
Test current: 205 mA, ± 5 mA
Continuity Buzzer Operates at less than 5 Ω approx.
Measuring Range: 0,1 – 100 kΩ(0 – 10 MΩ on analog scale)
Accuracy: ±5%, ±2 digits
Open circuit voltage: 5 V ±1V
Short circuit current 20 μA, ±2 digits
Voltage (BM400/2, BM401/2, BM403/2 only)
Measuring Range: (i) 0 – 600 V DC (ii) 0 – 600 V a.c. (50/60 Hz) (iii) 0 – 450 V a.c. (400 Hz) (iv) 1,0 – 50,0 V AC/DC (0-500 V on analog scale)
Accuracy: <450 V DC or AC (50/60 Hz):± 1%, ±2 digits 1,0 – 50,0 DC or AC 2% ±3 digits>450 V DC or AC (50/60 Hz):± 2%, ± 2 digits AC at 400 Hz: ± 5% ± 2 digits
Default Voltmeter
The default voltmeter operates when an external voltage >25 V AC or DC is detected on any range except OFF and . If this voltage exceeds 55 V then insulation testing will be inhibited. When this occurs, all instruments, except the BM402/2 and BM404/2, will revert to the voltage range display. Reverse polarity d.c. will cause ‘- d.c.’ to appear on the voltage measuring instruments. The BM402/2 and BM404/2 will beep and flash ‘V’ on the display as a warning. If external volts are present, testing will be inhibited.
Auto Shut off
The instrument auto shut-off operates 5 minutes after the start of a test, on all ranges, except the insulation ranges where it operates after 12 minutes. This can be adjusted to 60 minutes for the voltage, continuity and KΩ ranges. Selecting an insulation range or off will revert the shut-off to 5 minutes.
Battery Type:: 6 x 1,5 V cells IEC LR6 type only.
Battery Life: 3000 5 second operations, at 1 kVworst case