Aluminum wiring - What’s the issue?

Between 1965 and 1973, single-strand aluminum wiring was commonly used as a substitute for copper when wiring residential electrical systems.  Due to rising prices in copper, aluminum was a much cheaper alternative and, at the time, was believed to be a safe alternative.  However, over time, inherent problems and weaknesses were discovered that caused single-strand aluminum wiring to be discontinued from use.

So what’s the big deal?  The big deal is that aluminum is not quite as durable as copper.  Aluminum is a softer metal, and expands and contracts much more easily than copper does.  Because of this expansion and contraction, connections in outlets, switches, and light fixtures become loose, causing them to become more dangerous over time.  Why is loose wiring a problem? Loose wiring causes poor connections, and poor connections lead to overheating, which is a fire hazard.

Expansion and contraction aren’t the only problems aluminum wiring possesses.  It also has a higher electrical resistance, meaning the wire itself must be larger in diameter to carry the same amperage that a smaller copper wire can carry.  It is also less ductile, meaning it cannot handle all the bending that is required to wire a home with electricity, as well as copper wiring can.  The aluminum wiring breaks down more easily because of this, causing even MORE resistance, which creates problems with carrying the current required by the fixture, creating another fire hazard.  Aluminum also has problems with oxidation and galvanic corrosion.  As the wiring gets exposed to oxygen, it’s natural reaction is to oxidize.  Aluminum oxide is less conductive than copper oxide, and over time the aluminum oxide will deteriorate the connections, causing a fire hazard.  Additionally, any time aluminum wiring comes into contact with a dissimilar metal in the presence of moisture, corrosion will occur, causing deterioration of the connections as well.

So what do you do if your home has aluminum wiring? Fortunately, there are some options for correction, albeit some more expensive than others.  Option one is the most obvious, but the least cost effective: re-wiring the home with copper.  Granted, not all buyers may have the budget or the desire to have this done to their prospective home, so other options are available.  Option number two is to use copalum crimps.  This involves attaching a copper wire to the existing aluminum wire branch circuit with a specially designed sleeve and crimping tool.  An insulating sleeve is then placed around the crimping connector to complete the repair.  This repair is effective, and slightly less expensive that re-wiring the entire home, but it still does come out between $40-$70 per fixture, switch, or outlet that needs to be repaired.  The least expensive option is known as “pig tailing”.  This method is where at each connection to an outlet, switch, or fixture, a small piece of copper wire is attached to the aluminum wire using a twist on connector.  This way, it is the copper wire that is attached to outlet, switch, or fixture- thus helping eliminate the expansion and contraction at the actual connection.   Unfortunately, this method is not considered a “permanent” repair by the Consumer Products and Safeties Commission.  “CO/ALR” is a similar alternative to pig tailing, as this method uses a device that is intended for direct connection to aluminum wiring.  However, these products have been known to fail.

All in all, if your home inspector informs you that your house is wired with single-strand aluminum, the best thing to do is have the system thoroughly evaluated by a licensed electrical contractor who has experience in dealing with aluminum wiring.  Aluminum wiring does not have to be the end all be all, but it needs to be addressed in order to maintain the safety of your home and family.

Source: InterNACHI