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The Hazards of Aluminum Wiring

During the mid 60’s to early 70’s (65-73) approximately 1.5 million houses in the United States were wired with aluminum rather than copper.  This was done because of a price spike in copper during the mid 60’s.  This wiring has been linked to many fires because of faulty aluminum wires since that time.  According to studies conducted by the National Fire Protection Association, houses wired with aluminum are 55 times more likely to have a connection that reach a fire hazard.  We see quite a bit of aluminum wiring in Montana and in a recent visit to an aluminum wired house saw multiple burned  outlets caused by bad aluminum connections. This prompted us to write this article to educate our customers on the risks involved with aluminum wiring.

The problem with aluminum wiring does not lie in the wiring itself, it lies in the connection made to an outlet or switch.  The connection issue is caused by a few different properties of aluminum wire.

The main issue is called “Cold Creep.”  When aluminum heats up it expands more than copper and when it cools down it contracts more than copper.  Over time this can cause a loose connection at the outlet or switch.  Additionally, it is harder to make a tight connection with aluminum wire in the first place because aluminum wire has to be a thicker gauge wire than copper to carry the same electrical current.  All metals also oxidize over time but there is a primary difference in how copper oxidizes compared to aluminum.  When copper oxidizes it forms a conductor which creates no threat.  When aluminum oxidizes it develops as a resistor which causes a major threat.  Resistance causes heat which could lead to the outlet or switches burning up and possibly catching on fire or the insulation melting around the wire causing additional fire risk.  To make matters worse, if an outlet or switch meant for copper connections was used it causes oxidation to accelerate when the two unlike metals come in contact with each other. 

The US Fire Administration reports that of the 800,000 residential fires in the US yearly, about 11-12% of them began in the electrical system.  Here are some warning signs that you can look for ahead of time.

Outlets that spark

Smoke from outlets of switches

Lights that flicker when on

Cover plates around outlets or switches that are warm to touch

Melted insulation at connections

Smell of burning plastic

Blown fuses or breakers that trip

Light bulbs that burn out fast or are really bright

Have us come look at your electrical systems and we can make recommendations on the best way to handle your situation and give you a risk assessment. 

2 Responses to “The Hazards of Aluminum Wiring”

  1. BeatsPro says:

    When I bought my condo 10 years ago I was told had aluminum wiring…Not knowing much about the industry I thought this was odd. It sucks always having to buy outlets or switches made specifically for aluminum wiring. The choice is never as good. I still can’t believe that aluminum wiring got approved for building homes! Aluminum oxidizes so easily. What did they do in World War II when there was a shortage of copper? I think building costs just went up naturally, they didn’t look for a substitute. But by the Vietnam War I think builders were probably less burdened by ethics. Anyway, great article thank you.

  2. ericpetersen says:

    It’s amazing how often this issue is coming up lateley just because of the age of the aluminum systems and the fact that insurance companies are becoming more aware of the true hazard. If you have any further questions don’t hesitate to give us a call and thanks for the note!

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