Situated in the City of London, this 26-floor building is the new HQ for Willis Group Holdings, one of the world's most important insurance businesses. As well as 44,129m2 of office floor space, the building also incorporates street-level shops and cafés.

The cables chosen for the Tower's fire detection and alarm system are (of a low firehazard type. This provided the required superior flame retardancy and circuit integrity.

The contribution of a material to a fire - including that of the cable's own construction - is measured as the reaction to it in terms of smoke opacity, the emission of hazardous gasses, heat release and flaming droplets. It is essential that the production of opaque smoke and other such harmful emissions is maintained as low as possible during a fire, so that building occupants can escape quickly and safely along designated exit paths. The low fire-hazard cables chosen for the Willis Tower provided the required reaction to fire.

Easy installation

The cable use in the Willis Tower was manufactured to BS 7629-1:2008 (Electric cables. Specification for 300/500 V fire resistant screened cables having low emission of smoke and corrosive gases when affected by fire. Multicore and multipair cables), and meeting the 'Standard' category of BS 5839-1:2002+A2:2008 (Fire detection and fire alarm systems for buildings - Code of practice for system design, installation, commissioning and maintenance).

This cable has also been third-party tested and approved by both the Loss Prevention Certification Board (LPCB) in the UK, and by the British Approvals Service for Cables (BASEC).

The electrical contractor involved in the Willis Tower project has also recently installed similar low fire-hazard cables in several other major commercial buildings, including the Bankside Two and Three buildings next to the famous Tate Modern art gallery, and the One Kingdom Street building at the Paddington Central development.

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