Why Aluminum Wiring Is a Fire Risk — and How Pigtailing Fixes It

TL;DR: Homes built roughly between 1965 and 1973 often used aluminum branch-circuit wiring, and the Consumer Product Safety Commission has found that connections in these homes are up to 55 times more likely to reach fire-hazard conditions than copper. Aluminum expands and contracts more than copper, loosening at outlets, switches, and junctions over decades, which causes arcing and heat. The standard fix is pigtailing: an electrician splices a short length of copper wire onto the aluminum using a special connector (like a COPALUM crimp or AlumiConn connector), so only copper touches your devices and fixtures.

_Last reviewed: July 2026 · 7 min read_

If your house was built in the late 1960s or early '70s, there's a real chance the wires behind your walls are aluminum, not copper, and that fact matters more than most homeowners realize. The risk isn't the metal itself. It's what happens at every connection point after 40 or 50 years of heating, cooling, and loosening.

Okoniq Property Hub helps you log when an electrician inspected your panel or outlets, so you're not guessing years later whether that flickering light was ever checked out.

Why is aluminum wiring more dangerous than copper?

Aluminum wiring is riskier than copper because it expands and contracts more with temperature changes, and it oxidizes faster when exposed to air at a connection. Every time a circuit heats up from use and cools down again, the aluminum wire moves slightly against the screw terminal or wire nut holding it. Over hundreds of cycles, that connection loosens.

A loose connection creates resistance, and resistance creates heat. Add the oxide layer that forms on exposed aluminum (which conducts poorly compared to copper), and you get a connection that can arc, heat up, and eventually ignite the surrounding material, whether that's a wall stud, insulation, or the plastic in an outlet.

The CPSC studied this in the 1970s after a string of house fires traced back to aluminum branch wiring installed roughly between 1965 and 1973, when copper prices spiked and aluminum became a cheaper substitute. Their finding: homes with aluminum wiring, especially where it terminates directly on devices not rated for it, showed failure rates dramatically higher than copper-wired homes of the same era.

How do you know if your house has aluminum wiring?

You can often tell by checking the wire jacket at an outlet or your electrical panel, where aluminum wire is usually marked "AL" or "ALUMINUM" in the printed text along its insulation. Copper wire has a reddish-brown, shiny appearance when stripped; aluminum is dull silver-gray.

The most reliable check is at the panel itself, where an electrician can see the wire gauge and markings clearly. If your home's original electrical work dates to 1965-1973 and you haven't had a full rewire, aluminum wiring is worth assuming until proven otherwise. Outlets and switches that feel warm to the touch, discolored cover plates, or a faint burning smell near a receptacle are warning signs that a connection is already stressed, not just a maintenance curiosity. If you're also dealing with a fixture that's misbehaving, see replacing a ceiling light fixture safely before you touch any wiring yourself.

What is pigtailing and how does it fixes the problem?

Pigtailing means an electrician splices a 4- to 6-inch length of copper wire onto the existing aluminum wire using a connector engineered for aluminum-to-copper joints, then attaches only the copper pigtail to your outlet, switch, or fixture. The aluminum wire never touches the device directly again.

Two connector systems dominate this repair. COPALUM crimps use a specialized tool (only certified electricians have access to it) to permanently crimp a copper sleeve onto the aluminum wire, creating a cold-welded, gas-tight connection that doesn't rely on spring tension. AlumiConn connectors use a mechanical setscrew block rated for aluminum-copper mixing and don't require the proprietary crimping tool, which is why many electricians prefer them for retrofit jobs.

| Method | How it works | Typical cost per point | Notes | |---|---|---|---| | COPALUM crimp | Cold-weld crimp, tool-certified electricians only | $40-$65 per connection | CPSC-recognized, considered the gold standard | | AlumiConn connector | Setscrew block, no special tool required | $20-$40 per connection | Easier to source, widely used, UL listed |

Both approaches solve the same core problem: they remove aluminum from direct contact with your devices, switches, and fixtures, which is where most of the arcing and heat damage occurs. For a full walkthrough of the repair process and what an inspection includes, see the aluminum wiring safety fix guide.

How much does it cost to fix aluminum wiring, and is it worth it?

A full pigtailing job for an average 3-bedroom house with 30-40 connection points typically runs $1,500 to $4,000, depending on your region and whether the electrician uses COPALUM or AlumiConn. That's meaningfully less than a full rewire, which can run $8,000 to $15,000 or more depending on wall access and square footage.

Pigtailing is worth it because it addresses the actual failure point (the connection) without tearing open walls to replace the wire runs themselves, which are usually fine as long as they're not damaged or overloaded. Insurance companies increasingly ask about aluminum wiring during underwriting, and some require proof of pigtailing or a full rewire before issuing or renewing a policy, so getting it documented protects both your safety and your coverage.

While an electrician is in your walls, it's a reasonable time to also check outlets near sinks and tubs, since childproofing electrical outlets covers the GFCI protection standards that often get missed in older homes.

FAQ

Is aluminum wiring illegal in the US?

No, it's not illegal to have aluminum wiring in an existing home, but it's no longer used for new residential branch circuits because of the documented fire risk, and many local codes require pigtailing or upgraded connectors before a home can pass a resale inspection.

Will homeowners insurance cover a house with aluminum wiring?

Some insurers will decline or non-renew a policy on a home with unremediated aluminum wiring, while others charge a higher premium; getting pigtailing done and documented by a licensed electrician typically satisfies underwriting requirements and can lower your premium.

Can I pigtail aluminum wiring myself?

It's not recommended. COPALUM crimping requires a certified tool that isn't sold to the public, and even AlumiConn connectors require correct torque and technique to avoid recreating the same loose-connection problem; a licensed electrician typically charges $150-$300 per hour for this work but it's a one-time fix done right.

How long does aluminum wiring last before it needs attention?

Aluminum wiring itself can last indefinitely as a conductor, but the connections at outlets and switches degrade over roughly 15 to 25 years of use, which is why homes from the 1965-1973 era are now well past the point where inspection is overdue.

Is COPALUM or AlumiConn the better fix?

COPALUM is considered the more permanent, CPSC-recognized solution because the crimp is cold-welded and doesn't rely on spring tension, while AlumiConn is a solid, code-approved alternative that's easier to find and slightly cheaper per connection; either is far safer than leaving aluminum wire connected directly to a device.

This is educational information, not electrical or safety advice. Call a licensed electrician to inspect your home's wiring and perform any pigtailing or connector work.