Kiểm tra khoảng hở đèn âm trần (downlight)

How this is calculated#

A recessed luminaire, usually a downlight, sits in the ceiling with its body in the roof space. Its heat has to go somewhere, so AS/NZS 3000 sets which classes may go where and how close insulation may come. The class is the symbol on the luminaire or its box.

The tool first reads the marking. A luminaire marked to the 2001 standard is read as its current class: an IC-F as IC-4, a CA 80 as CA90. Then it checks the class against the list for your country and installation. A New Zealand home may take CA90, CA135, IC and IC-4. An Australian home may take Do-not-cover, CA90, IC and IC-4. Other buildings add Non‑IC and Do-not-cover, and New Zealand adds CA135.

Next it checks the insulation you plan against the class. IC and IC-4 may be covered. CA90 and CA135 may have insulation against their sides but not over the top. Do-not-cover may be near insulation but not touch it. Non‑IC is not tested with insulation, so the tool warns when insulation is present even kept clear.

Where insulation is kept clear and the maker gives no distance, the tool gives the default clearances of the standard for a lamp up to 100 W, for the dimensions its drawing shows for the class. Above 100 W there are no defaults: use the maker's distances or a luminaire certified for the condition. Last, it says whether the roof space needs the warning sign.

Worked examples#

• A CA90 downlight with insulation against its sides. The luminaire is Permitted in a New Zealand home. Insulation may abut it but not cover it, the space above stays clear, and the roof space needs the sign.
• An old IC-F downlight under insulation. The marking reads as IC-4, so the luminaire is Permitted and may be covered. No sign is needed if every downlight in the space is IC or IC-4.
• A CA135 downlight in an Australian home. The luminaire is Not permitted and fails: CA135 is not on the Australian list for any installation.
• A 50 W Non‑IC downlight in a shop. The luminaire is Permitted in a non‑residential building. Insulation must stay clear by the default clearances, with a fixed guard where it is loose.
• A downlight with no marking. The luminaire is Not permitted and fails: with no class and no stated clearances, it should not be installed.

Limits#

The tool reads the class and the clauses. It does not test a luminaire or check the maker's instructions, which take the place of the defaults. It does not size the lighting circuit or check its cable in the insulation; use the correction factors tool for a cable run in insulation. Spotlights that heat the surface they light follow Table 4.2, which the tool does not check.

See also: Downlights and insulation: IC-4, CA90 and Non‑IC, Downlights in an insulated ceiling and Lighting lumen method.