manufacturing a mineral-insulated cable that would compete with the Pyrotenax product. The manufacturers of the products "Bicalmin" and "Glomin" eventually merged with the Pyrotenax company. The Pyrotenax company introduced an aluminum sheathed version of its product in 1964. MI cable is now manufactured in several countries. Pyrotenax is now a brand name under nVent (formerly known as Pentair Thermal Management). Purpose and use MI cables are used for power and control circuits of critical equipment, such as the following examples: Nuclear reactors Exposure to dangerous gasses Air pressurisation systems for stairwells to enable building egress during a fire Hospital operating rooms Fire alarm systems Emergency power systems Emergency lighting systems Temperature measurement devices; RTDs and Thermocouples. Critical process valves in the petrochemical industry Public buildings such as theatres, cinemas, hotels Transport hubs (railway stations, airports etc.) Mains supply cables within residential apartment blocks Tunnels and mines Electrical equipment in hazardous areas where flammable gases may be present e.g. oil refineries, petrol stations Areas where corrosive chemicals may be present e.g. factories Building plant rooms Hot areas e.g. power stations, foundries, and close to or even inside industrial furnaces, kilns and ovens MI cable fulfills the passive fire protection called circuit integrity, which is intended to provide operability of critical electrical circuits during a fire. It is subject to strict listing and approval use and compliance Heating cable A similar appearing product is mineral-insulated trace heating cable, in which the conductors are made of a high-resistance alloy. A heating cable is used to protect pipes from freezing, or to maintain temperature of process piping and vessels. An MI resistance heating cable may not be repairable if damaged. Most electric stove and oven heating elements are constructed in a similar manner. Typical specifications Advantages The metal sheath and solid filling of MI cable makes it mechanically robust and resistant to impact; an MI cable may be struck repeatedly with a hammer and still provide adequate insulation resistance for a circuit. Copper sheathing is waterproof and resistant to ultraviolet light and many corrosive elements. MI cable is approved by electrical codes for use in areas with hazardous concentrations of flammable gas in air; an MI cable will not allow propagation of an explosion inside the copper tube, and the cable is unlikely to initiate an explosion even during circuit fault conditions. Metal sheathing will not contribute fuel or hazardous combustion products to a