Dealing with the halogen downlight conundrum

The 2007 Wiring Rules introduced a number of installation directives for halogen downlights because of the high incidence of fires directly attributable to the extreme heat output from them igniting nearby combustible materials. One of these directives is to leave considerable clearance around them from all materials, including insulation. But this introduces the problem of potentially compromising a home’s thermal efficiency. How do electrical contractors deal with this conundrum?

The Preface of the 2007 Wiring Rules provides an important directive on the installation of recessed luminaires, in particular halogen downlights: “Requirements for clearances of recessed luminaires to combustible building material and thermal insulation have been critically revised.”

The EL001 committee who wrote the standard had expressed concern over the high incidence of fires caused by incorrectly installed recessed luminaires. Section 4.5.2.3 of the Wiring Rules now calls for recessed luminaires and their auxiliary equipment to be installed so as to minimise temperature rise and prevent the risk of fire, outlining a choice of products and/or installation procedures to mitigate the risk of fire:

• Option (a) - Use luminaires certified by the manufacturer to permit:
  • contact with combustible materials; or
  • covering by thermal insulation material;
• Option (b) - Install luminaires within a suitable fire-resistant enclosure; or
• Option (c) - Provide clearances from combustible and thermal insulating material as specified by the luminaire manufacturer; or
• Option (d) - Provide clearances from combustible and thermal insulating material as specified by Figure 4.7 of the Wiring Rules, which is 200 mm for halogen downlights.

This last option causes the conundrum. Some electricians may take the line of least resistance - leaving clearance around a standard fitting. It’s quick, easy and costs no more. However, this is not the most desirable option because of the significantly negative impact it has on a building’s thermal rating. It should be understood that this option was introduced by the standards committee to encourage the electrical industry, in particular manufacturers, to progress away from conventional halogen downlights that emit excessive heat and cause fires, and move towards options (a) or (b). The large clearance areas effectively make it difficult for downlight positioning in modern houses because option (d) cannot be deployed in a house with 450 mm spacings between the framing.

In researching this topic, I poked my head up in a few ceilings and found entire insulation batts near halogens pulled aside from them, leaving half-square metre holes in ceilings without insulation. While you’re crouched in a cramped space in a ceiling void, it’s probably much easier and quicker to just leave off half an insulation batt than it is to neatly trim a 200 mm radius clearance around a downlight. But multiply that by 10 or 20 for the average number of halogen downlights found in a home and you have a serious compromise to its thermal properties. That’s not to say that contractors do it haphazardly, but it’s easy to take the simple option if you’re not fully aware of the consequential thermal rating compromise.

The thermal insulation problem

Phil Alviano, the Sustainable Building Advisor of the Master Builders Association of Victoria, points out that the Australian standard for thermal insulation installation, AS 3999, allows no more than 5% of gaps in insulation, adding: “So leaving large holes around light fittings can severely compromise a building’s compliance to that standard.

“Due to time constraints, it’s often difficult for installers to achieve this standard. At best, 95% is what most installers can realistically achieve. So when an electrician comes along afterwards and pulls up batts to put downlights in, unless he puts them back and covers up the lights, the performance of the thermal insulation is often compromised. But if he covers them up with the insulation, the risk of fire increases, so it’s potentially a no-win situation.

“The thermal efficiency of a building is determined at the design stage by an assessor accredited by the Association of Building Sustainability Assessors (ABSA), who then gives it an energy rating. It doesn’t get inspected on completion of the building so, in reality, the actual thermal performance depends on not only the insulation installer, but everyone else who might have to work around the insulation, which almost always includes the electrical trades.

“In fact, an electrical installation can compromise a building’s thermal efficiency, not only by having to leave big gaps around downlights, but also by holes left around power, phone and antenna points when they’re installed. It’s not uncommon for a tradesperson to tear away insulation to route cables and fit off points, without adequately reinstating it.”

This month, the Building Code mandated measures to compensate reduction in insulation performance caused by the installation of exhaust fans and recessed downlights. Table 3.12.1.1a in the Code lists the amount of compensation required to offset reductions in ‘R’ insulation values. For instance, a 1% reduction in a building in a moderate climate would require a 20% increase in thermal insulation. And in extreme climates, a 5% reduction in insulation would require a 140% increase as compensation. The table’s explanatory notes state that a 1% reduction in thermal insulation in a 200 m² home equates to an exhaust fan in a kitchen, laundry and two bathrooms, and just 10 downlights with 200 mm insulation clearance. So if you’re installing a large number of halogens into a home or office, you’ll probably find that choosing option (d) could become far more expensive than options (a) or (b).

The 2007 Wiring Rules acknowledges this issue in Appendix E - Electrical Installation Requirements in National Building Codes, stating: “Of particular concern for electrical installations is the making good of service penetrations in building insulation, the installing of insulation around light fittings that emit heat and the applying of building insulation over electrical cables. The Guides to Volume 1 of the BCA and Volume 2 of the BCA contain advisory information drawing attention to providing adequate clearance between ceiling insulation and light fittings. Clause 4.5.2.3 of this Standard contains requirements for such clearances.”

Clause 4.5.2.3 also states that “recessed luminaires must be installed in a way that cooling air movement around the luminaire is not impaired by thermal insulation. Where thermal insulation is loose fill, a barrier or guard constructed of fire-resistant material shall be provided and secured in position to maintain the default clearance.”

Solutions to the conundrum

In a ceiling, combustible materials such as linings, joists, beams and ducting can be adequately dealt with through proper installation. But dust and leaves can build up around the fitting over time, as can debris and nests from vermin and birds, adding to the risk of combustion. In fact, there’s a well-documented case a few years ago in NSW of an electrical contractor’s own home burning down from a fire caused by a bird’s nest on top of a halogen downlight igniting and spreading through the roof.

So the area around downlights is often an uncontrolled environment, which is best addressed with a permanent fire break. That prevents debris in close proximity to the downlight from igniting, while allowing insulation to remain close to the downlights and therefore not compromise the thermal rating.

Downlight protection manufacturer Arrowform issues a warning to contractors who install halogen downlights that can emit considerable heat: “The default clearances of option (d) in the Wiring Rules - the provision of required clearances - also demand that extraneous factors such as debris and vermin are fully considered before this option is taken for a firebreak. In this application, a larger gap is a larger trap for loose combustibles. The Victorian manager of a large electrical contracting firm who manages installations throughout the state recently said to us: ‘If contractors use option (d), they haven’t done their homework!’

“Our advice to contractors is to always include combinations in their quotations that are designed to run cool enough to cope with all factors. Installers should also check fine print carefully to ensure they’re not using poorly designed downlights that require costly heat-forward lamp replacements in the future, in order to run cool enough. Property owners should be anticipated to use low-cost replacement globes over time, which would increase external temperatures. For example, only four hours of exposure to combustibles is enough for potential ignition at 140 °C.”

As a manufacturer of both ‘run-cool’ halogen downlights and heat shields and permanent fire breaks for conventional halogens, Arrowform has been researching various ways to prevent halogen downlights causing fires for many years. The company suggests that before contractors choose any of the downlight installation options, it’s important to ask several questions to ensure they’re making the right choices:

• Will the protection offered meet one of options (a), (b), or (c), in Clause 4.5.2.3, including all of the qualifying paragraphs?
• Do the installation instructions show protection against all of the common situations that the downlight can be subjected to, including future loose insulation, leaves, vermin and debris?
• Does the product include a genuine enclosure?
• Is the product made of enduring fire-resistant materials?
• What would it take to dislodge the downlight protection?
• Will the downlight require an expensive heat-forward replacement lamp in future to comply with the maximum surface temperatures required by AS/NZS 60598?

Getting answers to these questions should at least put the contractor in a more knowledgeable position about product choice and installation practices to not only minimise the risk of fire from an unguarded halogen downlight, but also enable them to confidently reinstate the thermal insulation around the fitting and not compromise the building’s thermal rating.

From my research, there are a number of products that can satisfy options (a), (b), or (c) of Clause 4.5.2.3 so that option (d) need not be considered. I’ve come across light fittings that reduce high-temperature globes to safe levels in ceilings, moulded plastic enclosures that house a halogen lamp and transformer, fire-resistant downlight covers that enclose lamps and ‘cones’ fabricated from intumescent material that fit over lamps. Using these sorts of products with downlights helps to minimise the risk of fires while retaining a building’s thermal rating.

Making the right choices

Arrowform adds another caution to installers: “Be aware that if any installation retains fire risk, you are basically carrying the risk of fire for the life of each downlight at your own expense. This leaves your licence, your insurance cover and your future at risk. Is there any point paying for just partial protection of high-temperature fittings and retaining the risk when you can provide full protection by making the right choice?

“How do you make the right choices? Obviously the quality of the installation depends on workmanship, but you can’t expect to achieve that without using trustworthy products. Only use downlight protection products certified by an accredited test laboratory to do all that the standard requires. Ask to see the certificate of approval to AS/NZS 3000:2007 Clause 4.5.2.3 with a unique approval number. Don’t forget to check for comprehensive instructions - they’re vital.

“If a contractor’s chosen downlight installation combination (light fitting, permanent fire break and installation procedure) allows them to be positioned largely where clients want them, doesn’t open up a client’s ceiling area to the living zone, minimises heat/conditioned air loss, doesn’t cause draughts, doesn’t allow noise transfer and prevents the ingress of pollution and insects, then it’s a professional installation that’s on track for many recommendations.”

Alviano adds a final word of advice, noting the degree of influence electrical tradespeople can have: “Electrical contractors should be more conscious of the impact their choices and installation practices have on the thermal efficiency of a building, making sure they’re fully aware of the options they have at their disposal and the subsequent benefits to their clients. They should also be aware of their power to persuade their clients on anything electrical. People typically view electrical tradespeople as the most knowledgeable people when it comes to electrical services. So, rather than just installing basic fittings, electrical contractors should be saying to their clients: ‘I can install this or that, but have you considered ‘XYZ’ that can give you all these extra benefits.’ I’m sure contractors would find their clients only too happy to adopt their recommendations when the benefits are spelled out to them.”