Subj: Aluminum Wiring / What is the deal?|
Date: 08/13/2000 3:42:53 PM Eastern Daylight Time
Aluminum Wiring / What is the deal?
"I just had a home inspection done and the inspector noted the aluminum wiring. I have suggested to my buyers to have a licensed electrician inspect the entire system. I've never run into this before. Any other suggestions?" Thought for the week
Dealing with the aluminum wiring issue is like walking on a bed of hot coals. On one side are some independent home inspectors, electricians and others telling you it's bad stuff, have it replaced with copper. On the other side a local senior code enforcement inspector stating that he has seen very few problems and the electrical codes stating that aluminum wiring is OK. Where is the truth and why is there such confusion?
Warning: This gets a little technical but it will be well worth your time and patience!!
There is nothing wrong with aluminum "wire" (but don't stop reading here)! Most of the high-voltage transmission lines in the United States are made of aluminum. Almost all modern houses, including the one you are now living in has "stranded" aluminum wire on the main service entrance and major appliance circuits. Don't let your client get out of joint because some home inspector shows aluminum wire in his report. If he doesn't have it in his report he is not meeting the current state and ASHI standards. You will see it in almost all of my reports.
Now that we have that straight, lets get to the meat of this issue. On April 28, 1974, two persons died in a home fire in Hampton Bays, New York. Fire officials determined that the fire was caused by a faulty aluminum wire connection at an outlet. Since that tragic accident, the U.S. Consumer Products Safety Commission and other government agencies have investigated numerous complaints throughout the nation relating to trouble with small gauge aluminum branch circuit wiring. The Commission has also had research conducted that shows that homes wired with aluminum wire manufactured before 1972 ("old technology" aluminum wire) are 55 times more likely to have one or more connections reach "Fire Hazard Conditions" than is a home wired with copper.
Now are you totally confused? The truth is it's OK and it's not OK. Is that clear?
Plainly stated, aluminum "wire" is fine. "Small gauge aluminum branch circuit wiring" installed prior to 1972 and improperly installations after 1972 may not be. The issue is not the wire it is the wiring connections on small gauge circuits. Aluminum wiring properly installed meeting current industry standards and code requirements should be perfectly safe.
Aluminum wire does not behave the same as copper wire. The installation procedures are different. Prior to 1972 aluminum wiring was installed the same as copper wire. Some electricians today and most amateurs have failed to observe the different requirements. Aluminum wire has approximately a 30 percent higher expansion/contraction rate than copper (it moves more). When aluminum wire is exposed to the atmosphere, a film of aluminum oxide (like rust, only white) forms on the metal surface. The oxide is an insulator, not a conductor of electricity. These two properties, working together, in old technology aluminum wire (pre-1972) and improperly installed circuits cause the problems. As the oxidation continues to build up on the wire, it builds resistance. Heat comes with the resistance melting the insulation. The expansion/contraction rate of aluminum wire loosens the connection points cause arcing and short circuits, these two in turn causing fires.
Simply stated, white rust forms on the bare wire at the connections causing the wire to overheat melting the insulation of the covered wire. The rust lubricates the connection and as the wire moves with changes in temperature the connection works loose causing sparks. One of the two starts a fire. This is why the problems are worse in exterior walls.
To farther exacerbate the situation, copper to aluminum connections oxidize faster and the use of stick-in, as opposed to screw connections, make the wire easier to pull out.
This oxidation and movement is not as much of a problem in stranded wire (multiple wires stranded together) where high voltages are involved. However, oxidation is a problem with residential wiring because the current is supplied at much lower voltage in solid conductor (non-stranded) wire.
What are some of the symptoms of a problem?
Signs of trouble in aluminum wiring systems include warm-to-the-touch face plates on outlets or switches, flickering lights, circuits that don't work, or the smell of burning plastic at outlets or switch. Unfortunately, not all failing aluminum wired connections provide such easily detected warning signs; aluminum wired connections have been reported to fail without any prior indications or problems and these are the same symptoms found in problems with copper wiring.
How the problem has been addressed:
In 1972, manufactures modified both aluminum wire switches and outlets to improve the performance of aluminum-wired connections. The switches and outlets are labeled
"CO/ALR." CO indicates that the device is acceptable for copper wire, and ALR means it is acceptable for aluminum wire. The aluminum wire should be stripped to allow from 2/3" to3/4" wrap around and must be attached to terminal screws in the clockwise direction. A torque screwdriver should be used to tighten the screw to 12"-lb. (inch-pounds). After tightening the screws on the device, a coating of an antioxidant compound to protect the wire from the atmosphere must be applied to all exposed surfaces.
In 1995 Ideal Industries, Inc. introduced a new type of wire nut for use with aluminum wire. This nut incorporates a number of innovations, such as a paste fill that serves as a corrosion inhibitor, a square-wire spring that grips the wires better etc. This is claimed to be acceptable for copper to aluminum connections. There has been much controversy involving the acceptability and performance of this connection.
The only undisputed recognized method of connecting copper wire to aluminum is a COPALUM parallel splice connector manufactured exclusively by AMP Incorporated and used only by AMP certified electricians. This tool makes a permanent connection that is in effect a cold weld. An insulating sleeve is placed around the crimp connector to complete the splice.
Can the pre-1972 installations be fixed?
Yes, there are several options:
1. The most expensive repair is to rewire with copper wire leaving the old aluminum wire in place or removing it. This is not only the most expensive, but also the most difficult. It is difficult to rewire most homes without removing wall finishes in many locations. Many people pay to have this done. They are convinced the wire is the problem, which as stated above is not the case. Many repair companies prefer this method for two reasons. They make more profit and most are not certified to use the AMP system. Quoting the U.S Consumer Product Safety Commission "This is the most expensive method … but if you can afford the cost, it is the best method available."
2. The "COPALUM Crimp Connector Repair" must be performed by an AMP Incorporated certified electrician using AMP manufactured equipment and components. This repair installs a copper pig tale on the end of the aluminum wire making all device connections using copper wire. This is an expensive but viable option and as far as I am aware is the only "repair" recommended by the U.S Consumer Product Safety Commission. (Note: There are many other brands and types of crimp connectors which are readily available to consumers. The U.S. Product Safety Commission does not believe that these common varieties of crimp connectors can be used to reliably repair aluminum wiring.)
3. Replacing all devices with switches and outlets rated and labeled "CO/ALR" making splices using the 1995 Ideal Industries, Inc. wire nut (Note that this option remains in dispute).
Homes built before 1965 are unlikely to have aluminum branch circuit wiring. Homes built, rooms added, and circuits rewired or added between 1965 and 1973 are more likely to contain aluminum wiring installed using the old technology. The issues found in wiring installed after 1972 are failure to use devices rated
"CO/ALR" and failure to use or properly use an antioxidant compound to protect the wire.
Aluminum wire is still in the National Electric Code. Some cities (not around here) have passed an ordinance restricting aluminum wire use, but the ordinance affects only construction from the date the ordinance went into effect. All homes built before those dates are
grandfathered. If a real estate inspector observes a problem, he/she should report it but does not have the authority to determine the type of repair. The problem should be investigated and if necessary repaired by a licensed electrical contractor.
Here is an example of what you might see in one of my reports:
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