Aluminium wiring was commonly installed in New Zealand homes built or rewired between roughly the late 1960s and early 1980s, when copper prices spiked and aluminium was used as a cheaper alternative. While it was considered acceptable at the time, aluminium wiring is now known to carry significant fire and safety risks if not properly managed — and identifying it early is an important step in keeping your home safe.
Why Aluminium Wiring Is a Concern
Aluminium behaves differently from copper in several important ways that make it more problematic in household wiring:
- Oxidation: Aluminium oxidises quickly when exposed to air, forming a layer of aluminium oxide on the surface. This oxide is a poor conductor and increases electrical resistance at connection points, generating heat.
- Thermal expansion: Aluminium expands and contracts more than copper with temperature changes. Over time, this causes connections to loosen, creating arcing and overheating risks.
- Softness: Aluminium is a softer metal and can be damaged more easily during installation or when connections are tightened, leading to poor contact.
- Galvanic corrosion: When aluminium wiring is connected directly to copper terminals or devices not rated for aluminium, galvanic corrosion can occur, further increasing resistance and heat.
These factors combined mean that aluminium wiring — particularly at connection points such as switches, outlets, and the switchboard — is associated with a higher risk of electrical fires.
Which Homes Are Most Likely Affected?
If your home was built or significantly rewired between approximately 1965 and 1985, there is a reasonable chance it may contain aluminium wiring. This era coincides with the period when aluminium was most widely used in residential electrical installations in New Zealand. Homes in this age range — particularly those that haven't had a full rewire — are worth investigating.
How to Identify Aluminium Wiring
Check the Switchboard
The easiest place to look for evidence of aluminium wiring is your main switchboard (consumer unit). With the board cover removed — ideally by a licensed electrician — you may be able to see the wiring. Aluminium wiring is typically:
- Silver-grey in colour (copper wiring is orange-brown)
- Marked with the letters "AL" or "ALUM" on the cable sheathing
- Sometimes wrapped in grey or beige insulation rather than the red/black/green common with copper
Do not attempt to open or work inside your switchboard yourself — this is restricted electrical work under New Zealand law and must only be carried out by a registered electrician. See the Electrical Workers Registration Board (EWRB) for more information on what constitutes restricted work.
Look at Accessible Wiring in the Roof or Subfloor
If you can safely access your roof space or subfloor cavity, you may be able to inspect wiring runs without touching them. Look for the silver-grey colour and "AL" markings on the cable jacket. Never handle or disturb wiring yourself.
Check Outlet and Switch Faceplates
Warm or discoloured power outlet faceplates, flickering lights, or frequently tripping breakers can all be warning signs of overheating at aluminium wiring connection points. These symptoms warrant urgent investigation by a professional.
Commission a Building or Electrical Inspection
The most reliable way to identify aluminium wiring is to have a licensed building inspector or registered electrician carry out a thorough inspection. A building inspector can flag visible signs and advise on next steps, while an electrician can test the system and assess connection integrity. If you're buying an older home, always request a pre-purchase inspection that specifically checks for aluminium wiring.
What Are the Risks if Left Unaddressed?
Untreated aluminium wiring connections are a recognised fire hazard. Loose or corroded connections can arc and ignite surrounding insulation or timber framing — often inside walls where a fire can spread undetected. BRANZ, New Zealand's building research authority, and WorkSafe NZ both recognise electrical faults as a leading cause of residential fires.
Insurance implications are also worth considering — some insurers may limit cover or require remediation if aluminium wiring is identified in your home. Check your policy carefully.
What Can Be Done About It?
If aluminium wiring is confirmed, a registered electrician can advise on the best remediation approach. Common options include:
- Full rewire with copper wiring — the most comprehensive solution
- CO/ALR-rated devices — replacing switches and outlets with devices specifically rated for aluminium wiring
- Pigtailing — joining short copper extensions to aluminium wires at each connection point using approved connectors (this must be done by a licensed electrician)
All of these are restricted electrical work under the Electrical (Safety) Regulations 2010 and must be carried out by a registered electrician who will issue you a Certificate of Compliance (CoC).
When to Call a Professional
You should contact a registered electrician immediately if you notice:
- Warm or scorched power points or light switches
- Flickering lights or frequently tripping breakers
- A burning smell near outlets or the switchboard
- Any visible damage to wiring insulation
For a general assessment of your home's condition — including identifying whether aluminium wiring may be present — a licensed building inspector is an excellent first step. You can find qualified local building inspectors and electricians on tradedirectory.co.nz.
Safety note: Never attempt to open your switchboard, handle wiring, or carry out any electrical work yourself. All electrical work in New Zealand must be performed by a registered electrician and certified with a CoC.
Licensed Building Practitioner (LBP)
BCITO Qualified
