For some time now (without getting overwhelmingly technical) I have wanted to do a blog about Aluminum Wiring---the solid conductor stuff that was widely used from 1965 to 1975. It originally became popular as the prices of copper when through the roof. Like copper it was widely used in residential construction for 15 and 20 amp branch circuits. By the early 70's there was already evidence that there were problems related to the wiring being brittle, so the alloy was modified to be less brittle. The aluminum wire expands and contracts a lot more than copper, so at the connections, as the wire expanded/contracted, gaps would start to develop which would lead to arcing. Arcing is almost always bad juju when it comes to electricity---unless you want to weld something.
In this first picture we see a beautifully wired 1967 vintage electrical panel. It is interesting because "technically" the only defect is the improper terminations of the newer copper circuits that have been added (neutrals and grounds terminated together).
Another issue with the aluminum wire is that it is very soft, so much so that any knick could in effect reduce the wire size at the knick. Such a nick acts like a fuse leading to: arcing---as we now know---bad juju. So imagine we start to do some remodeling in the home and we start to mix copper wire with the aluminum wire. In this next picture we can see the combination of copper and aluminum wires at the red wire not and the completely burned away wire nut at the bottom right corner of the junction box
In this next picture we see splices of aluminum wire outside of a junction box in an attic with obvious melting. In both of these cases the wire nut are not rated for use with aluminum wiring.<
As previously discussed these wire types have different rates of expansion and contraction and which can lead to: arcing---everyone beginning to get the picture? These are just a few of the more serious issues that are associated with aluminum wire and they all can lead to serious fire safety concerns. Because almost every aluminum wired house that I have inspected has had some arcing related conditions that could have resulted in loss of property or life, it is perhaps the my least favorite issue to find in a home----and often results in my buyer walking away from the deal.
While, there is some controversy over what to recommend and do about houses with aluminum wiring, the end result is going to be expensive. There are specific repairs accepted by the Consumer Product Safety Commission, involving installation of Copalum Connectors , that are considered by some to be an acceptable solution. There are very few contractors certified to make these connections (and are only recommended on the "second-generation" type wire). My concern with this approach is this: is "every" "single" connection going to be locatedto be properly repaired? (These homes are going to be at least 40 years old---has any remodeling been done that might have resulted in buried/hidden junction boxes?) I have come around to the position that the "best" protocol is to rewire the home (especially those pre-1970 houses), and if that is not an option then to have the Copalum Connectors installed and add AFCI type circuit breakers to the circuits. These types of breakers are designed to pick up the kinds of arcing conditions associated with aluminum wiring.
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WA State, Home Inspector Advisory Licensing Board