almost certainly involve extensive use of LSZH cable. This will reduce the chance of toxic gases accumulating in those areas where personnel are working and the lack of corrosive gases where there are computer controlled systems will reduce the possibility of wires being damaged by fire resulting in a short circuit fault. Since the 1970s, the wire and cable industry has been using low-smoke, low-halogen materials in a number of applications. The introduction of a thermoplastic LSZH extended its use to accessories such as heat shrink tubing, labelling and fixtures. The objective was to create a wire and cable jacketing system that was not only flame retardant but also did not generate dense, obscuring smoke and less toxic or corrosive gases. In the military field its introduction was accelerated after 1982 following the dense black smoke emitted from HMS Sheffield after being hit by an Exocet missile in the Falklands war. Several fires, such as the King's Cross fire in London that killed 31 people in London's underground in 1987, increased the awareness of the contribution that wire and cable jacketing makes in a fire. As a result, there has been an increased use of LSZH cables. With an increase in the amount of cable found in residential, commercial and industrial applications in recent years, there is a greater fuel load in the event of a fire and LSZH systems have a major role to play in protecting the public. Several standards describe the processes used for measuring smoke output during combustion. For military applications Def Stan 02–711 in the UK and ASTM E662 in the US which are both based on an ASTM STP No. 422 pages 166–204, 1967 modified by AMTE, Portsmouth in the UK and superseded by E662 in the US. During these tests a specified material sample is standardised and then exposed to a radiant heat source; the optical density of the smoke given off is photometrically measured. There are various means of measuring optical density: peak smoke release rate, total smoke released, and smoke density at various points and durations during the test. Results must be below a certain value and the material must pass the burn test in order for the material to be labelled as low smoke. These tests are conducted under laboratory conditions and cannot claim to replicate the range of conditions expected in a real fire scenario. However they do provide