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Barriers and Isolators - Intrinsically safe

Barriers and Isolators - Intrinsically safe

Intrinsically safe (IS) systems provide safe operation of equipment in hazardous areas by limiting the amount of electrical energy in the circuit to levels where a fault cannot cause a spark that would ignite any explosive atmosphere that could be present. For an IS system to operate correctly, both the barrier or isolator and the devices in the hazardous area must be approved and designed to work together.

Barriers and Isolators both provide power limitations on an intrinsically safe circuit, but work in different ways. Barriers are the simpler, but require secure connections to a dedicated IS earth point. Isolators use more complex electronics but can operate earth-free and are more tolerant of supply voltage. Both Barriers and Isolators must be mounted in the safe area, but as close as possible to the hazardous area.


  BG3 Call Point  DB5 Sounder   DB6 Sounder  XB8 Beacon
Matching galvanic Isolator MTL5561 MTL5525 MTL5525 MTL5525
Number of circuits 2 1 1 1
Products per circuit 10 1 1 1
Maximum supply 35Vdc 35Vdc 35Vdc 35Vdc
Isolators per DX070 enclosure 4 4 4 4
Matching shunt barrier MTL7787+ MTL7787+ MTL7787+ MTL7787P+
Number of circuits 1 1 1 1
Product per circuit 10 1 1 1
Maximum supply 26.8Vdc 26.8Vdc 26.8Vdc 26.8Vdc
Barriers per DX070 enclosure 5 5 5 5
Description  Product Reference Catalogue Number
Isolating Interface & Housing to suit DB5 / DB7 / XB8 MTL5525 MTL5525
Isolating Interface & Housing to suit BG3 Call Point (2 Channel) MTL5561 MTL5561
Shunt Diode Barrier & Housing to suit BG3I / DB5 / DB7 MTL7787+ MTL7787+
Shunt Diode Barrier & Housing to suit XB8 MTL7787P+ MTL7787P+
DIN Rail Enclosure for Isolators and Barriers DX070 DX070


  • Isolators and barriers
  • IP65 protection
  • Multiple products per enclosure
  • 24Vdc operation
  • Matching range of MTL isolators and barriers to suit range of IS products
  • Enclosure can be used in most safe area environments
  • 4 isolators or 5 barriers can be fitted into the enclosure saving installation
  • 24Vdc systems to suit standard fire system operation