Downlights, dimmers & smart switching

Lighting Installation Sydney

Choosing the fittings is the easy half. The half that decides whether you are still happy in six months happens above the ceiling and inside the switch plate, where nobody looks until something buzzes.

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Insulation rating checked Dimmers matched to the driver Existing wiring assessed first

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370 °CWhat a halogen downlight can reach

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Above the ceiling

A downlight is the only appliance you deliberately bury in insulation

Everything else in a house is allowed to breathe. A recessed light is pushed up into a hole in the ceiling, surrounded by whatever is up there, and then left switched on for four hours an evening. That is why the interesting part of a lighting job is almost never the part you can see from the couch.

Fire and Rescue NSW is unusually direct about the older version of this. Halogen downlights, they say, generate very high temperatures that can reach up to 370 degrees, and if they are not correctly installed and maintained they can cause a fire. Their advice is to keep insulation off the lights and off their transformers, to avoid installing hard against structural timber, to make sure cooling air movement is not impaired, and to check periodically for debris and vermin damage. A ceiling full of fifty watt halogens is a ceiling full of small heaters aimed at timber and insulation.

The change that fixed most of this was not the lamp, it was the classification. Recessed luminaires now carry an abatement rating that states exactly what insulation is permitted to do around them, and the better ones can be abutted and covered completely. That single line on the box is what decides whether your ceiling insulation runs continuously or ends up with a hole cut around every fitting.

Which is why swapping a globe is only half a job. An LED lamp in a fitting rated for a halogen brings the heat down, and it leaves the classification, the transformer, the cut-out and the hole in the insulation exactly where they were.

The rating

What the letters on the box actually permit

Five classifications, and the difference between the bottom one and the top one is whether your ceiling insulation is continuous or full of holes.

Classification	May abut	May cover	What that means in a real ceiling
Non-IC, or unmarked	No	No	A clearance has to be kept and kept clear, so the insulation ends up with a hole around every fitting
CA80	Yes	No	Insulation can be packed against the sides, the top has to stay open
CA135	Yes	No	The same, at a higher temperature classification
IC	Yes	Yes	The ceiling can be insulated straight over the top of it
IC-F, also written IC-4	Yes	Yes	As IC, and sealed so insulation and debris cannot get inside the fitting

The numbers in CA80 and CA135 relate to the temperature classification rather than to a distance, so they are not a clearance you can measure with a tape. The line that matters to a homeowner is simpler: can insulation touch it, and can insulation go over it. Everything below IC answers no to the second question, and that answer has a cost.

Picture what a non-IC fitting requires in practice. A gap has to be maintained around it, permanently, in a space nobody visits. Ten of them across a living area is ten deliberate gaps in the insulation, in the ceiling, which is where a house loses and gains the most heat. The insulation installer and the electrician are almost never on site in the same month, so nobody sees the finished result as one system. Replacing non-IC fittings with IC or IC-F rated ones is one of the few jobs that improves safety and thermal performance at the same time.

Two related things are worth checking while the ceiling is open, and both come straight from the Fire and Rescue advice. Whether anything has been packed against or over the fittings since they went in, which happens every time a ceiling is re-insulated by someone who was not told. And whether there is debris or vermin damage up there, because nesting material against a warm fitting is exactly the combination the clearances exist to prevent.

Inside the switch plate

Whether you can have smart switches was decided when the house was wired

Not by the brand you buy, and not by the app. By which of two arrangements the original electrician used, decades before anyone sold a smart switch.

Scroll to see both arrangements →

What it means: a smart switch is a small computer, and a computer needs a circuit to draw power through even when the light is off. That takes an active and a neutral. Looped at the light, the neutral never reaches the switch plate, so there is nothing for the device to run on. Looped at the switch, everything it needs is already sitting behind the plate. Most Australian houses are the first kind, which is why so many smart switches are bought, opened and returned.

Looping at the light is the traditional Australian method and it is a perfectly good way to wire a house. The supply lands at the ceiling, the neutral connects straight to the fitting, and only the active goes down the wall to the switch and comes back up as a switched active. It uses less cable and it puts the joint somewhere accessible. Nobody was doing anything wrong. It just happens to be the wrong shape for a device that needs its own power supply.

There are three honest ways out and they cost very different amounts. Run a neutral to the switch, which is quick where the ceiling above is accessible and awkward where it is a slab, a cathedral ceiling or a top floor with no crawl space. Move the intelligence to the light instead, using a module that sits above the fitting and keeps the existing switch on the wall. Or use a device designed to work without a neutral, accepting that it powers itself by trickling current through the lamp, which is the same mechanism that causes ghosting.

The useful part is that none of this is a guess. Pulling one switch plate off the wall answers it for the whole house in about five minutes, and it is worth doing before the fittings are bought rather than after.

Dimming

Four symptoms, and none of them mean the lamps are faulty

Dimming an LED is not the same problem as dimming a filament, and almost every complaint traces back to that one difference.

Flicker, worse the lower you go

A leading edge dimmer chops the start of each half cycle. A filament has enough thermal inertia to ignore that completely. An LED driver is a switching power supply trying to hold a steady current, and below about half brightness it starts losing regulation.

Trailing edge dimming cuts the end of the cycle instead, with a softer ramp and no inrush spike, which is what an LED driver is built to accept. Most flicker complaints are a leading edge dimmer left in place through an LED upgrade.

An audible buzz from the dimmer or the fitting

Usually the same root cause seen from another angle. The sharp current spike at the start of each half cycle excites something mechanically, either in the dimmer or in the driver, and you hear it.

It is not dangerous and it is not a sign the fitting is about to fail, but it is a reliable sign that the dimmer and the driver were never meant to work together.

A faint glow when the light is off

Called ghosting. A dimmer with no neutral behind it has to power its own electronics somehow, so it draws a tiny current through the lamp itself. A filament never showed it. An LED driver stores enough of it to light up.

Long runs and two-way switching make it worse. The fixes are a neutral at the switch, a dimmer that behaves better on that circuit, or a bleed device at the fitting.

It drops out, or refuses to start at low level

Minimum load. Older dimmers were designed around filament lamps and often need something like 40 to 60 watts before their own electronics behave predictably. Eight LED downlights might total 60 watts. Six might total 48.

So a circuit that worked perfectly for years can become unstable the day it is converted, purely because the load fell through the floor of what the dimmer needs.

There is one shortcut through all of this. Every reputable LED driver manufacturer publishes a list of dimmers their product has been tested against, and that list is the only reliable answer to the compatibility question. A fitting sold for a dimmed circuit with no such list behind it is telling you something.

The work

What most lighting jobs actually are

Four categories cover nearly everything, and the difference between a cheap version and a good one is rarely the fitting.

Halogen to LED, done properly

Not a lamp swap. The old fitting and its transformer come out, an LED unit with an abatement classification suited to your ceiling goes in, and the insulation is made continuous again rather than worked around.

Where the new cut-out is a different diameter to the old one, that gets handled at the same time, which is usually cheaper than discovering it afterwards.

New points, pendants and wall lights

Adding a light where there is not one is an access question before it is a lighting question. A pitched roof over a plaster ceiling is straightforward. A slab, a cathedral ceiling or a top floor with no crawl space is a different conversation and a different price.

Pendants over an island or a table also need the fixing point thought about, because plasterboard alone will not carry a heavy fitting for twenty years.

Dimming and smart control

Starting from what is behind the switch plate rather than from a catalogue. If there is a neutral, smart switches are simple. If there is not, the choice is running one, moving the control to the light, or accepting the compromises of a no-neutral device.

Where dimming is the goal, the dimmer is chosen against the driver's published compatibility list, not by matching brands and hoping.

Switching that suits the room

Two way switching at both ends of a hallway or a staircase, splitting one overloaded switch into separate circuits so the room is not all on or all off, and putting the switch where people actually reach for it rather than where the cable happened to land.

It is the least glamorous item on this page and the one people mention most afterwards.

Compliance

What we will not do to your ceiling

Licence 387609C Level 2 accredited & insured

We will not push insulation back over a fitting that is not rated to be covered, and we will not leave one buried if we find it that way. If a ceiling has been re-insulated over non-IC fittings at some point, that gets reported rather than quietly restored, because the clearance exists for a reason and the next person up there will assume it was correct.

Fittings are selected with the abatement classification stated in the quote, so the rating is a decision rather than a detail discovered on the day. Where a fitting is unmarked, it is treated as though it may be neither abutted nor covered, which is the safe reading rather than the convenient one.

All of it is certified as electrical work. We lodge a Certificate of Compliance for Electrical Work within 7 days of the compliance test, which since 1 July 2026 goes through the BCNSW eCert portal. Where a lighting job needs its own circuit, or the board has no spare way, that becomes a switchboard upgrade and is quoted as such rather than absorbed.

Good to know

Lighting questions

Can I just put LED globes in my halogen downlights?

You can, and it will cut the heat and the running cost, but it does not finish the job. The fitting itself keeps the classification it was built with, so if insulation had to be held clear of it before, it still has to be held clear of it now. The transformer stays where it is, the cut-out stays the size it is, and the gap in your ceiling insulation stays exactly as big as it was. Replacing the whole fitting with one rated for insulation contact is what actually closes that gap.

What does IC rated mean, and do I need it?

It is the abatement classification, and it says what insulation is allowed to do around the fitting. Non-IC means insulation must not abut it or cover it, so a clearance has to be kept forever. CA80 and CA135 mean insulation may abut the sides but must not cover the top. IC means it may abut and cover. IC-F, sometimes written IC-4, is IC plus sealed against insulation and debris getting inside. In an insulated ceiling, IC or IC-F is what you want, because everything below that leaves a permanent hole in your insulation.

Why do my LED lights flicker when I dim them?

Usually because the dimmer was designed for filament globes. A leading edge dimmer chops the start of each half cycle, which an incandescent filament simply smooths out and an LED driver does not. Trailing edge dimmers cut the end of the cycle instead and suit LED drivers far better. The other common cause is minimum load: older dimmers often need 40 to 60 watts to run stably, and eight LED downlights may not add up to that. Every reputable driver has a published list of compatible dimmers, and that list is the only reliable answer.

Why do my LEDs glow faintly when they are switched off?

It is called ghosting and it is a wiring symptom rather than a faulty lamp. A dimmer with no neutral at the switch has to power its own electronics by trickling a small current through the light itself. A filament never noticed it. An LED driver has enough stored energy in it that the same trickle produces a visible glow. Long cable runs and two-way switching make it worse. The fixes are a neutral at the switch, a different dimmer, or a bleed resistor at the fitting.

Can I install smart switches in my house?

It depends on something decided when the house was wired. Most Australian homes are looped at the light, which means only an active, a switched active and an earth come down to the switch plate, and a smart switch has no neutral to run on. Homes looped at the switch have all three and take a smart switch straight away. Where there is no neutral, the options are to run one, to put the control at the light instead of at the switch, or to use a no-neutral device and accept its limits. That is a five minute check at a switch plate, not a guess.

Do you need to get into the roof space?

For anything involving downlights, new points or moving a fitting, usually yes, and it shapes the quote more than the fittings do. An accessible pitched roof over a plaster ceiling is straightforward. A cathedral ceiling, a concrete slab, a top floor with no crawl space or a roof space full of blown-in insulation is a different job. It is worth telling us which you have when you call, because it is the single biggest variable.

How does your pricing work?

Attending your job is a chargeable callout. We confirm what it costs when you book, and the price for the work itself is agreed before we start, so there are no surprises on the invoice.

Where we work

Lighting installation across the North Shore

Based in Castlecrag, covering all of Sydney. A few of the suburbs we work in most:

This page is about installation. For where the light should go and what colour it should be, see outdoor lighting design; for beam angles and spill, flood lights; and for detection and control settings, sensor lights. Related work: ceiling fans share the same ceiling access, rewiring is the answer where the lighting circuits have no earth, and common area lighting in apartment blocks is strata electrical. See the full list of locations we service.

Getting quotes on downlights?

Upfront pricing, with the price agreed before we start. Ask whoever quotes you what abatement classification they are fitting.

Call 0401 427 270 Request a quote