Aluminum wiring: how to tell, and what fixes it

Why aluminum was used and why it fails

A copper shortage in the mid 1960s pushed builders to use aluminum wire for ordinary 15 and 20 amp branch circuits, not only for big appliances. The federal Consumer Product Safety Commission (CPSC) says homes built before 1965 are unlikely to have it, and cables put in between 1965 and the mid 1970s, including additions and rewired circuits, may.

The trouble is at the connections. Aluminum and the devices it connects to change over time, resistance goes up, and the joint gets hot. CPSC cites a survey in which homes built before 1972 and wired with aluminum were 55 times more likely to have outlet connections reach what it calls “Fire Hazard Conditions” than copper-wired homes. The same publication notes that failing connections seldom show warning signs. The aluminum wiring risks guide covers the background.

Finding out

Check the cable jacket where it is visible, in an unfinished basement, attic or garage. A flashlight at a low angle helps read embossed markings. Aluminum cable carries “AL” or “Aluminum” along the jacket. If it says “CU-clad” or “Copper-clad” it is copper-coated aluminum, and the repair rules in the CPSC publication do not cover it. Aluminum branch wire is also thicker: No. 12 and No. 10 for 15 and 20 amp circuits, against No. 14 and No. 12 for copper. Larger aluminum wire for service entrances, dryers and ranges is a separate matter.

An electrician can confirm quickly. Do not open outlets on your own with the power on.

The three fixes CPSC accepts

Method	What happens	Notes
Rewire with copper	New copper cable replaces aluminum	CPSC calls it the best method, but impractical for many homes
COPALUM	Short copper tails are crimped to the aluminum at every connection	Permanent; needs a special tool and trained installer
AlumiConn	Copper tails joined with setscrew connectors	CPSC’s “next best alternative” where COPALUM is not available

The COPALUM repair should cover every connection, including outlets, switches, fixtures, appliances and junction boxes. Skipping some defeats the purpose.

What CPSC does not recommend

• Twist-on wire nuts used to pigtail copper to aluminum. CPSC says this may fail even more often than the original connection.
• Hand-crimped connectors sold at retail.
• CO/ALR switches and receptacles as a standalone fix.

Contractors sometimes offer these because they cost less. If a bid uses one, ask them to show where CPSC accepts it. The agency lists only the three methods above.

Choosing between a repair and a rewire

A repair keeps the walls closed and costs less per connection. A rewire removes the aluminum and also lets you update circuits, add grounds and meet current protection rules. Where the house has attic or crawl-space access, rewiring can be reasonable. Published cost guides put a whole-house rewire at about $7,200 to $20,000 nationally (Fixr and Bob Vila), and the SoCal range on the whole-house rewire cost page is $8,000 to $20,000 as of October 2026. COPALUM and AlumiConn repairs have no published SoCal price list, so ask for itemized quotes per connection.

A partial rewire also works if only some circuits are aluminum.

Permit

Rewiring and most repairs are done under an electrical permit and city inspection. Ask the electrician which method will be used and how many connections are included. The whole-house rewire page describes the full job.

Selling a home with aluminum

Buyers, lenders and insurers ask about it. See home sale electrical inspection. A written record of the repair method and the electrician’s license helps.

Questions to ask each bidder

• Which of the three CPSC methods will you use, and at how many connections?
• Does the price include appliances, fixtures and junction boxes, or only wall outlets?
• Is the electrician trained for COPALUM, and if not, which connector is used instead?
• How will you document the repair for my insurer and a future buyer?
• Are the permit and inspection included?

If you rent or are buying

Tenants should report warm outlets or burning smells to the landlord in writing. Buyers can ask the seller for any repair records and ask an inspector to check cable markings in the attic and at the panel. A house with unrepaired aluminum is not unsellable, but the repair cost belongs in the negotiation.