Things to know about: Aluminum Wiring
When shoping for a home, it is important for buyers to know about, and understand, aluminum wiring. This article looks at the situation from a real estate perspective; it is important to contact a licensed electrician for assistance.
Copper is widely known as one of the best electrical conductors readily available to the marketplace and has been used in wiring applications since the discovery of electricity. During the 60s, the demand for copper as well as its price was skyrocketing, making the use of copper wiring cost prohibitive. There was an alternative already approved for use in wiring applications, and that was aluminum, a much cheaper alternative with ample supply at the time. Although aluminum is not as conductive as copper, this could be compensated for by using larger gauge wire to move the same current safely and that is what was done. Between the early 60s and the late 70s, aluminum became widely used as wiring material for homes throughout North America.
Aluminum had some differences in installation which were not always followed strictly by the installers. Aluminum required more care to prevent nicking or breaking of the wire itself or the sheathing, and special plugs and switches were designed to use aluminum wire. Especially in the early and late years of use, when the industry was transitioning into and out of aluminum wire use, the specialized plugs and switches weren’t readily available, or more expensive and anti-oxidization compounds were not widely used.
So, what is the deal with these extra requirements that copper didn’t need? Aluminum is not as good of a conductor and the resistance in the alloy produces more heat than copper naturally, which is why the larger gauge wire was used to compensate. When copper oxidizes its oxidation is also a good conductor of electricity, but unfortunately when aluminum oxidizes, its oxidation is not a good conductor leading to increased resistance and more heat. To add to the problem, aluminum oxidizes not only in the air but mainly in contact with other metals so as basements were developed in the 80s and 90s and wired with copper, those junction connections between aluminum upstairs and copper downstairs also caused this oxidation heat issue. If that wasn’t enough, aluminum also expands and contracts at a different rate than copper and brass, so when twisted with copper in a junction box, or screwed down on a brass terminal for a plug or switch, the expansion and contraction of the aluminum with its heat resistance issues cause the aluminum to work its way out of these connections over time. This condition is called “Cold Flow” and will eventually cause arcing as the electricity tries to jump from the loosened wire to the connection with can cause heat, sparking and fire to surrounding flammable building materials.
So does that mean the entire house must be re-wired? Not at all, aluminum wire in the walls and ceiling is not the issue. The issue is primarily in the connection to other metals such as incorrect receptacles or joined to copper connections, so the simple solution is to correct those connections. The most common form of this remedy is a practice called “pig-tailing” which should be done by a licensed electrician. Basically, all the plugs and switches in the home are removed from the wall and a short piece of copper wire is connected between the aluminum service in the wall and the plug or switch itself. The connection between the aluminum and copper wire is made using a specialized wire nut and an anti-oxidizing compound. Then the new copper-rated receptacles can be placed back in the wall and are safe. A licensed electrician will also determine if junction boxes contain copper and aluminum connections which also require correct wire nuts and anti-oxidation compound.
How to tell if you have aluminum wires
Well, vintage should be your first hint. If the home is built between 1960 and 1980, or close to that, you should take a quick peek at the electrical panel. The wires coming out of the electrical panel will typically have printing on them every 12 inches and if they are aluminum will often have the abbreviation AL or ALUM or some variation of that. If you can’t tell that way, an electrician or licensed inspector can determine for you by opening the panel or checking certain receptacles.
At the time of writing this article, I have yet to hear of an insurance company that requires a house to be rewired from aluminum to copper. The main reason is that there is nothing wrong with aluminum wiring when installed properly and using the correct receptacles. In fact, the current electrical codes still recognize both copper and aluminum wiring as acceptable, although aluminum wire in household gauge is not manufactured anymore because of the stigma attached to it. It is normal however for an insurance company to require pig-tailing to be done within a certain number of days of the possession of a property to protect against the possibility of poor installation or bad connections.
Aluminum wiring has been largely unmarketable since the 70s and therefore not profitable for manufacturers to make it, or its specialized receptacles. The existence of aluminum wiring in a home is not a deal killer, but buyers need to understand there will be some additional due diligence required on their part, and sellers need to understand that some buyers may be nervous about the wiring in their home.
Article sourced by AREA blog