Fire Rated Cables, Heavy Duty (750 V)


A fire survival MI wiring cable system designed for versatility and ultimate fire survival performance. Provides a solution to many difficult and demanding wiring installations making a permanent and dependable wiring cable system for all low and medium voltage applications. Safe in hazardous installations and radioactive environments. Exceeds all worldwide fire performance standards. The Pyro MI Cable System is suitable for domestic, commercial and industrial applications. The cables are manufactured, tested in accordance with LPCB and BS EN 60702-1, BS 8434-2, BS 5839-1 Clause 26.2 (Enhanced), BS EN 50267-1, and BS EN 50200 Class PH 120.

Pyrotenax Terminations are tested in accordance with BS EN 60702-2. Pyrotenax Terminations are certified for use in potentially explosive atmospheres. Glands - Baseefa08ATEX0327X and IECEx BAS 08.0107X Increased Safety Seals - Baseefa02ATEX0194U.

Features and benefits:

  • Pyro MI survives the fire test requirements for enhanced grade cables as defined in BS 5839: part 1.
  • Third party (LPCB) approval for categories C, W and Z in BS 6387.
  • Also attains categories C, W and Z of BS 6387 with one single cable sample.
  • The standard range of Pyro MI Cable provides a solution for almost all electrical circuits in the low voltage category.
  • Available with conductors from 1.0–240 mm². A light duty version is also available, specified separately.
  • Resistance to fire (950°C for 3 h – category C).
  • Resistance to fire with water spray (650°C – category W).
  • Resistance to fire with mechanical shock (950°C – category Z).
  • High operating temperatures and corrosion resistance.
  • Zero energy and non-ageing.
  • Great mechanical strength.
  • Small overall diameter.
  • Pliable.
  • Wiring cable and conduit combined.
  • High degree of electrical screening.
  • Radiation resistant.
  • Integral earth continuity.
  • CE marked.

With a basic inorganic construction of a copper sheath and conductors, together with a mineral insulant, the cable provides dependability, versatility and permanence. This construction, with the melting points of 1083°C and 2800°C for the copper and the insulant respectively, provides the unsurpassed fire survival properties which enable the cable to continue to carry current at temperatures in excess of 1000°C.

Pyro Twist Cables:

Pyro Twist is a range of communication and signal cables for life preservation and integrated building management systems. They have been developed from the proven characteristics of Pyro MI to maintain the security of vital signals in communication and data networks, particularly in hostile conditions.

  • Twisted conductor configuration with a solid copper screen.
  • Available in red (other colours available upon request).
  • Uses standard accessories for the equivalent Pyro MI Light Duty cable size.
  • Can be installed and terminated by following the normal procedures for Pyro MI Cable.
  • The twisted copper conductor configuration enhances the EMC noise rejection characteristics, reducing the possibility of system malfunction.
  • The exceptionally low impedance of the solid copper sheath provides a superior EMC screening than other cable systems.
  • Minimal smoke obscuration in the event of fire.

Seals and Insulators:

A seal is normally required at each end of a Pyrotenax MI Cable to provide a means of electrical connection. The Standard Brass 105°C Seal is suitable for the majority of general wiring applications. However since Pyrotenax Cables are used in a wide variety of environments, a comprehensive range of seals and insulators are available to suit every need. A complete termination comprises a seal to provide a means of electrical connection and a gland to secure the cable into the appropriate apparatus.

Externally threaded brass compression glands are available with ISO metric threads as standard. Other thread forms are available on request.

General information

Specification data - Heavy-duty mineral-insulated cables

Product Reference

Fire Rated Cables, Heavy Duty (750 V)


Extensive range available, consult literature and insert requirements.


Fire resistant seal

High temperature glazed insulator

Increased safety seal

Standard seal

Product Options


- Fire resistant seal:

When fire resistance is required, standard Pyrotenax 105°C seal Ref. RPS can be used provided that the standard PVC sleeving is replaced by silicon elastomer coated glass braided sleeving Ref. RZPS. Such seals will pass a circuit integrity test, essentially as given in BS 6387 for category C, with seals in a 950°C flame for three hours.

- High temperature glazed insulator:

For environments up to 250°C, a glazed insulator can be constructed as follows:

  • Use the brass screw on pot from a standard seal (ref RPS).
  • A cap or disc is not required.

- Increased safety seal:

Continuous operating temperature range -20°C to +85°C. Intended for use with type of protection 'e' in potentially explosive atmospheres. Available in plain and earth tail. Typical seal references: Plain-RPA2H6 20. Earth Tail-RPAL2H6 25.

- Standard seal:

Continuous operating temperature range - 80–105°C. These standard seals are suitable for all general wiring applications. Available in plain or earth tail. Typical seal references: e.g. Plain-RPS 2L2.5 20. Earth Tail-RPSL2L2.5 20. e.g. Plain-RPS 2H6 20. Earth Tail-RPSL2H6 20.