Fire in the hole

There is an increasing awareness by builders, architects, surveyors, electrical contractors and, in particular, building inspectors of the fire protection needs of all recessed downlighter installations. In domestic housing, downlighters must have the correct protection added to ensure that the fire and acoustic properties of the ceiling lining are reinstated.

Standard protection

The need to provide fire protection in downlighter installations is well covered in regulations. Building Regulations Approved Document B (Fire) states: “If a fire-separating element is to be effective, then every joint, imperfection of fit or opening to allow services to pass through the element, should be adequately protected by sealing or fire-stopping so that the fire resistance of the element is not impaired”

The IEE Wiring Regulations 16th Edition BS 7671:2001 Section 527-02-01 says: “Where a wiring system passes through elements of building construction such as floors, walls, roofs, ceilings, partitions or cavity barriers, the openings remaining after the passage of the wiring system shall be sealed according to the degree of fire resistance of the element concerned.”

As a result of this growing awareness throughout the industry and its associated bodies, recent legislation and guidance is being more specific about light fittings and their penetration of the ceiling lining. For example, the DTI-sponsored Ensuring best practice for passive fire protection in buildings published last year states: “Lighting fittings and other penetrations through the ceiling must also have the same demonstrated standard of fire resistance and be appropriate for the type of ceiling.”

As now being highlighted by Building Regulations Part E, the ceiling membrane also has a critical role to play in maintaining the acoustic rating of the structure. Perforation of a ceiling will result in a downgrade of its acoustic properties and any downlighter fitted or its protection must be capable of restoring that rating.

Robust details, published in May 2004, contains information on separating floor structures that have undergone extensive sound insulation testing and can be used as an alternative to pre-completion testing. These only allow the use of downlighters and recessed lighting that have been satisfactorily assessed; are fitted to the manufacturer’s instructions in ceiling voids of over 75 mm; include no more than one light per two square meters of ceiling area; and must be protected to Part B. In the case of a timber floor, any protection must have been tested to BS 476 Parts 21 and 22. Fire and acoustic covers tested to Part 23 are not applicable to wooden floored structures.

Approved Document Part P, issued in July, becomes a legal requirement in January 2005. Regulation 4 (2) states that on completion of work the building should be no worse in terms of the level of compliance with other applicable parts of Schedule 1. These may include, but are not limited to, Parts B, E, F and J. For example, one or more perforations of a ceiling lining beneath a floor, made to accommodate recessed lighting or similar fittings, may have an adverse effect on that floor’s performance in terms of its resistance to fire and sound penetration. Due regard should therefore be paid to the guidance given in Approved Document B (Fire safety) on the performance of fire resisting and compartment floors, and Approved Document E (Resistance to the passage of sound). Installation must be by a competent person.

The revision of Approved Document B is expected to consider perforation of the ceiling lining in some detail.

Controlled lighting

This new focus on downlighter applications, plus the proliferation of their use and the numbers being fitted per room in new homes, has increased the attention paid to downlighter protection by Building Control. It is now quite common for 30 to 40 units to be fitted per new build property. This has resulted, quite properly, in unprotected downlighter installations being rejected by Building Control surveyors.

There are now regular instances of electrical contractors who, in order to comply with Building Regulations that are now being more strictly applied, are having to rework unprotected installations, very often at their own expense.

It is forecast that the use of downlighters will grow. They mix well with other lighting elements; create the feeling of space in a room; are efficient; quality brands have a lamp life in excess of 3000 hours; they give twice the light output of conventional lamps; and they are a very attractive solution to providing lighting schemes that conform to Part L of the Building Regulations.

Home help

For domestic applications, protection is provided by the use of lighting covers or the fitting of downlighters where the fire and acoustic protection is built into the light unit. The type of protection selected should be appropriate for the ceiling floor structure and capable of providing protection for the life of the installation. If fitted correctly, in the event of a fire this passive protection can prevent, or at least delay, the progression of lethal smoke and gas.

Some downlighters get very hot in use, with temperatures at the rear of the fitting exceeding 200ºC. Fire covers can protect the fitting from coming into contact with any flammable or insulating materials present in the void. Being manufactured from intumescent fibre material, they have good acoustic properties. However, they can be difficult to fit, can cause overheating of the lighting unit that can result in reduced lamp life, and if they are of a vented design to prevent this overheating they may lose their acoustic performance.

The simplest, most economical, quickest and safest – the protection having been properly installed – solution is to select from one of the ranges of downlighters now on the market that have protection built directly into the lighting unit. These will have been tested in representative ceiling/floor structures to BS 476 Parts 21 or 22. They will also have had a full acoustic test, both airborne and impact, and be capable of being in contact with materials in the void without creating a fire hazard or overheating problems.

The Snaplite low voltage range is manufactured under licence by Electro-Technik. This has inbuilt protection with fire ratings up to 1·5 hours, meets all the above test criteria, is simple to install from below and is approved by Lantac. Snaplite has been designed so that the increased use of insulation in the ceiling void will have no effect on its operation. The electronic transformer must, of course, be sited in an area of reasonable ventilation.

Another situation, very often overlooked, is when the rear of a downlighter projects upwards into an open roof space. Again, protection must be installed to prevent stored items in this area from coming in contact with the rear of the fittings and causing a fire hazard.

A number of serious roof fires have resulted from unprotected installations and consequential liability may rest with the installer. To comply fully with Building Regulations all recessed downlighter installations, whatever their application, must be protected by one of two means: either fitting an appropriately tested fire cover or installing products that include inbuilt protection.