Quick answer
Aluminum wiring is house wiring that uses aluminum conductors instead of copper, and in US homes the term usually means the small aluminum branch circuits for outlets and lights installed from about 1965 to the mid-1970s.
The concern is the connections. CPSC found that pre-1972 homes wired with aluminum were 55 times more likely to have outlet connections reach fire hazard conditions than copper-wired homes.
Quick facts
The key facts about Aluminum Wiring, with sources:
- Installed mainly
- 1965 to the mid-1970s, during a copper shortage 2
- Main hazard
- Overheating at connections and splices 2
- Survey finding
- Pre-1972 aluminum homes 55 times more likely to have outlet connections reach fire hazard conditions 2
- How to spot it
- "AL" or "Aluminum" printed on the cable jacket 2
- Sizes used
- 12 AWG for 15 A and 10 AWG for 20 A circuits 2
- CPSC-recognized permanent repairs
- Rewire with copper; COPALUM crimp pigtails; AlumiConn connector if COPALUM is unavailable 2
Key takeaways
- Aluminum wiring is not the same as aluminum service cable; the concern is small branch circuits.
- Homes wired between 1965 and the mid-1970s may have it 2.
- The wire itself is not the main problem; connections can overheat with no warning signs.
- CPSC lists three permanent fixes: rewiring with copper, COPALUM pigtails and, where COPALUM is unavailable, AlumiConn connectors 2.
- Every repair is a job for a qualified electrician.
If you think you have aluminum wiring
Safety and risk
Do not open outlets, switches or the panel to check. CPSC warns that doing it yourself can get you electrocuted or make the problem worse 2.
Hot-to-the-touch cover plates, flickering lights, dead circuits or a smell of burning plastic are reasons to stop using that circuit and call a licensed electrician. If you see smoke or flame, leave and call 911.
What aluminum wiring is
In the mid-1960s a copper shortage led builders to move aluminum wire from large circuits, such as dryers and ranges, into everyday 15- and 20-amp outlet and light circuits 2. That is what people mean by "aluminum wiring" in a house.
CPSC says homes built before 1965 are unlikely to have aluminum branch wiring, while cable installed from 1965 to the mid-1970s in new homes, additions and rewired circuits may contain it 2. It looks like ordinary plastic-sheathed NM cable from the outside.
Large aluminum conductors are still common and accepted today for service entrance cables and feeders. CPSC's repair advice does not apply to those larger conductors, or to dryer and range circuits 2. This page is about the small branch circuits.
How aluminum connections fail
CPSC describes several aging processes at aluminum connections that raise resistance over time. The damage builds on itself. More resistance means more heat whenever current flows, sometimes to dangerous levels 2.
The failures happen where wires end or join: outlets, switches, junction boxes and the connections at appliances such as dishwashers and furnaces 2. The wire inside the wall usually is not where the fire starts.
In the CPSC-funded survey, "fire hazard conditions" meant an outlet cover screw reached 149°C (300°F), sparks came from the outlet, or nearby material was charred 2.
- Connection agesdeterioration at the screw or splice
- Resistance risesmore opposition to current
- Heat buildswhen the circuit carries load
- Damage adds upthe joint gets worse each cycle
- Back to step 1
Source: [2]
Kinds of aluminum conductors in a home
| Type | Where found | Status |
|---|---|---|
| Solid aluminum branch wiring (12 and 10 AWG) | Outlets, switches, lights in 1965 to mid-1970s homes | The fire concern CPSC addresses 2 |
| Copper-clad aluminum | Some branch wiring of the era | Not covered by CPSC repair advice; marked "CU-clad" 2 |
| Stranded aluminum service and feeder cable | Service entrance, subpanel feeders | Common today; outside CPSC's branch repair advice 2 |
| Aluminum range and dryer circuits | Large 240-volt appliances | Outside CPSC's branch repair advice 2 |
Example: why aluminum circuits use a larger size
Aluminum carries less current than copper of the same size, so aluminum branch circuits were sized one step larger. This example compares manufacturer chart values in the 75°C column.
| Size | Copper ampacity (75°C) | Aluminum ampacity (75°C) |
|---|---|---|
| 12 AWG | 25 A 3 | 20 A 3 |
| 10 AWG | 35 A 3 | 30 A 3 |
| Branch circuit practice | 14 AWG for 15 A, 12 AWG for 20 A | 12 AWG for 15 A, 10 AWG for 20 A 2 |
So a 15-amp aluminum circuit has thicker wire than a copper one. That is one clue an electrician uses. The printed "AL" on the jacket is the surer sign.
Where to look, safely
CPSC says nearly all aluminum branch wiring was installed as plastic-sheathed NM cable. Look at the printed or embossed markings on cable jackets in unfinished basements, attics or garages. A flashlight held at a low angle helps read embossed text. Aluminum cable is marked "AL" or "Aluminum" every few feet 2.
Read the whole marking. "CU-clad" or "Copper-clad" with "AL" means copper-coated aluminum, which CPSC's repair advice does not cover 2. If you cannot see any cable, ask an electrician or home inspector. Do not remove cover plates.
Why it was used, and what still works
There is no safety benefit to aluminum branch wiring in a home today. The honest angle is why it was chosen and where aluminum is still fine.
Why it is a problem
- Connections can fail and overheat with no prior warning signs 2.
- Ordinary outlets and switches not rated for aluminum are a poor match.
- Twist-on connectors used as "pigtail" repairs overheated in CPSC testing 2.
- Some insurers charge more or decline homes with it, which can affect coverage or a sale 1.
- Every connection in the house must be addressed to get the full benefit of a repair 2.
What drives the cost of fixing it
Cost depends on the repair method and the number of connections. Rewiring with copper removes the hazard but may be impractical or costly in finished homes 2. Pigtail repairs scale with the count of outlets, switches, fixtures, boxes and appliance connections, since CPSC says each one should be done.
COPALUM is installed only by electricians trained by the maker using a special tool, which affects availability 2. We do not quote prices without dated, sourced figures. See aluminum wiring remediation for how the work is scoped, and the project cost tool for drivers.
The repair options CPSC recognizes
CPSC names three permanent repairs and warns against two common shortcuts. All require a qualified electrician 2.
| Method | What it is | CPSC view |
|---|---|---|
| Rewire with copper | New copper branch circuits; old aluminum abandoned | The best method, but may be impractical or expensive |
| COPALUM crimp pigtail | Short copper lead joined to aluminum by a tool-applied crimp | Safe and permanent; trained installers only |
| AlumiConn pigtail | Set-screw connector joining copper to aluminum | Next best if COPALUM is unavailable; shorter track record |
| Twist-on connector pigtails | Standard wire nuts | Not recommended; overheated in testing |
| CO/ALR devices only | Outlets and switches rated for aluminum | Not a full permanent repair in CPSC's view |
Rewire
- Removes aluminum
- Most disruptive
COPALUM
- Keeps wire, fixes every joint
- Trained installers only
AlumiConn
- Keeps wire, fixes every joint
- Use if COPALUM is unavailable
Source: [2]
Sources: [2]
Living with aluminum wiring until it is fixed
There is no owner maintenance that makes aluminum connections safe. What you can do: avoid heavy loads such as space heaters on aluminum circuits, keep working smoke alarms, and notice warm plates or odd smells.
After a repair, keep the records. They help with insurance and resale. An electrician should check any later additions use rated connectors.
Warning signs CPSC lists
CPSC notes failing aluminum connections often give no easy warning 2. When signs do appear, they include:
- Cover plates on outlets or switches that are hot to the touch.
- Flickering lights.
- Circuits that stop working.
- The smell of burning plastic at outlets or switches.
Any of these calls for a licensed electrician. Our electrical safety check lists other red flags, and emergency electricians handle urgent cases.
Authorities and rules
The main federal guidance is CPSC Publication 516, Repairing Aluminum Wiring, dated June 2011 2. It is advice, not a law requiring homeowners to replace existing wiring. It distinguishes existing aluminum circuits from the larger aluminum conductors used today.
For new work, NFPA 70, the National Electrical Code, governs conductor sizes and terminations; Table 310.16 in the 2023 edition lists aluminum ampacity separately from copper 4 5.
Local codes adopt editions on their own schedule 6. CPSC's publication does not order existing wiring removed. When circuits are altered, repaired or extended, the local code official decides which edition the new work must meet.
Aluminum wiring compared with related terms
| Term | What it is | Connection to aluminum wiring |
|---|---|---|
| Wire gauge | Conductor size | Aluminum runs one size larger than copper |
| Wire connector | Device that joins wires | Must be rated for aluminum; key to repair |
| NM cable | Plastic-sheathed cable | How aluminum branch wire was installed |
| Knob-and-tube | Older open copper wiring | Different era and hazard; see knob-and-tube guide |
| Arc fault | Unintended arcing | Loose, hot connections can arc |
Myths about aluminum wiring
- Myth All aluminum wire is dangerous.
- Reality CPSC's concern is small branch circuits; large aluminum service and feeder cable is common today 2.
- Myth If nothing has happened yet, it is fine.
- Reality CPSC notes connections can fail with no prior warning 2.
- Myth Wire nuts fix it.
- Reality Twist-on pigtails overheated in CPSC testing and are not a recommended repair 2.
- Myth Swapping in CO/ALR outlets solves it.
- Reality CPSC does not consider that a full permanent repair 2.
- Myth Copper-clad is the same as aluminum.
- Reality CPSC's repair advice does not cover copper-clad aluminum 2.
Where it varies
When aluminum wiring matters to you
Aluminum wiring matters if you own or are buying a home built or rewired from about 1965 to the mid-1970s, or an inspection report mentions "single-strand aluminum". It also matters before adding loads or renovating, since new work must connect properly to old wire.
Next step: read our full aluminum wiring guide, then have a licensed electrician confirm what you have and quote a CPSC-recognized repair.
- If Home built 1965 to mid-1970s
- Then Look for "AL" on visible cable jackets
- If Jacket says AL, not CU-clad
- Then Get an electrician to assess
- If Warm plates or burning smell
- Then Stop using the circuit; call now
- If Choosing a repair
- Then Rewire, COPALUM or AlumiConn per CPSC
Source: [2]
Questions about Aluminum Wiring
Is aluminum wiring dangerous?
Aluminum branch wiring carries a higher fire risk than copper at its connections. A CPSC-funded survey found pre-1972 homes wired with aluminum were 55 times more likely to have outlet connections reach fire hazard conditions.
The risk sits at outlets, switches and splices. A CPSC-recognized repair reduces it. CPSC also warns that these connections can fail and overheat without any prior warning signs, so a quiet history is not proof of safety 2.
How do I know if my house has aluminum wiring?
Look at the printed markings on cable jackets in an unfinished basement, attic or garage. Aluminum cable is marked "AL" or "Aluminum" every few feet. A home built or rewired from 1965 to the mid-1970s is the likeliest. If you cannot see cable, have an electrician check. Do not remove covers.
What years was aluminum wiring used in homes?
CPSC says aluminum branch circuit wiring went into homes from about 1965 to the mid-1970s, during a copper shortage. Homes built before 1965 are unlikely to have it.
Additions and rewired circuits from that period may contain it even in older houses.
A 1950s house with a 1970 family-room addition, for example, can have aluminum in the addition only, so check cable in each part of the home.
Do I have to replace aluminum wiring?
Not necessarily. CPSC recognizes full copper rewiring as the best fix, but also two connection repairs that keep the existing wire: COPALUM crimp pigtails, or AlumiConn connectors where COPALUM is unavailable.
Each must be done at every aluminum connection by a qualified electrician. CPSC lists outlets, switches, light fixtures, junction boxes and hard-wired appliances among the places that need it 2.
What is pigtailing aluminum wiring?
Pigtailing joins a short copper wire to the end of the aluminum wire, so outlets and switches connect to copper. CPSC recommends it only with a COPALUM crimp or, as a fallback, an AlumiConn connector.
Pigtails made with ordinary twist-on connectors overheated in CPSC testing. A COPALUM crimp needs a special tool and a maker-trained installer, so ask any electrician who quotes it whether they hold that training 2.
Are CO/ALR outlets enough for aluminum wiring?
CPSC does not treat CO/ALR outlets and switches as a complete permanent repair.
They are rated for aluminum and work better than standard devices when installed carefully, but they do not address splices, boxes and appliance connections. CPSC prefers rewiring, COPALUM or AlumiConn.
CPSC accepts CO/ALR devices only as an emergency, temporary repair for a failed aluminum termination 2.
Does aluminum wiring affect home insurance?
Aluminum wiring can affect home insurance. Policygenius reports that many standard insurers charge more for or decline homes with aluminum branch wiring, and that an insurer may require repairs after an inspection. Policies differ by company and state.
Records of a CPSC-recognized repair by a licensed electrician give you something to show when you shop for coverage or sell. Ask your agent which repair methods the company accepts before the work starts, since rules differ.
Is aluminum wire still used today?
Yes, in larger sizes. Aluminum is common for service entrance cables and feeders to subpanels. CPSC's concerns and repair advice apply to small 15- and 20-amp branch circuits, not to these larger conductors 2.
CPSC also excludes dryer and range circuits from its branch repair advice. Large aluminum feeders need lugs rated for aluminum, which an electrician checks at every termination.
What is copper-clad aluminum wire?
Copper-clad aluminum has an aluminum core with a copper coating. Its jacket is marked "CU-clad" or "Copper-clad" with "AL".
CPSC notes its aluminum repair recommendations do not cover copper-clad wire, so an electrician should assess it separately.
CPSC notes that copper-clad and solid aluminum cable were sized the same way: 12 AWG for 15-amp and 10 AWG for 20-amp circuits 2.
Can I add new circuits to a house with aluminum wiring?
Yes. New circuits can be run in copper from the panel. Any place where new work connects to existing aluminum needs connectors rated for it.
Ask the electrician to inspect the existing aluminum connections at the same time. Opening walls for new work is a convenient moment to pigtail nearby aluminum outlets and switches as well.
Sources
- Policygenius, Does homeowners insurance cover aluminum wiring?, retrieved .
- U.S. Consumer Product Safety Commission, Publication 516: Repairing Aluminum Wiring (June 2011), retrieved .
- Cerrowire, Ampacity Charts (copper and aluminum, 2017 NEC basis), retrieved .
- NFPA, NFPA 70 (National Electrical Code) code development page, retrieved .
- NFPA, Free access to NFPA codes and standards, retrieved .
- NFPA, Where the NEC is enforced (adoption maps), retrieved .
Expert review
Written by the HyreElectrical Research team. Not yet reviewed by an outside expert. We say so rather than imply a review that has not happened; see our editorial policy.
How the numbers were checked: CPSC Publication 516 read in full (dates, survey finding, repair methods, warnings); ampacity values from the manufacturer chart. Held noindex (G-REV) until a qualified reviewer signs. No prices (G-COST).
Suggest a correction. We fix errors and say what changed.