This month I would like to discuss solid strand old-technology aluminum wiring.

Many homes built from about 1964 to 1978 may contain solid strand #12 and #10 aluminum wiring. The development of solid aluminum for home-building was in reaction to a shortage of copper and brass. This development and introduction to the market occurred without sufficient testing regarding the devices to which the wiring connects. At the time, all receptacles and switches were designed for use with copper wiring. The problems and risk of fire occurred because aluminum has a different rate of expansion and contraction than copper. Placing an aluminum wire under a brass screw on a standard receptacle may result in loosening of the connection which creates resistance, thus heat and possible fire.

When inspecting older houses I always check inside the main panel, looking for solid aluminum wire. If found, even if it looks to be in pristine condition, I always recommend that all devices be inspected by an electrician familiar with the repair of aluminum wiring to determine the condition and if the devices are aluminum rated. Modern aluminum receptacles are labeled "CO/ALR" to indicate aluminum rating. Older aluminum rated receptacles were labeled "CU/AL." I do not recommend that inspectors remove receptacle covers and pull out the receptacle to observe the connections - this risks damaging aluminum wire that may be brittle due to long term overheating.

Some older houses utilized aluminum "home runs" to junction boxes in the attic with copper being used down the stud cavity and to the receptacles and switches some the reverse. This can usually be found by inspecting the attic wiring and looking for "AL" in the label on some of the nonmetallic sheathed cables and "CU" on others. Sometimes I would remove the junction box covers to look at the equipment grounding conductors observing for solid aluminum. In this case the aluminum to copper wire-capped connections may be at risk for overheating. Again I recommend an electrician to evaluate.

There are many different methods to repair aluminum wiring from completely rewiring the house to "pig-tailing" at devices to just replacing the devices with ones rated for aluminum. I leave it up to the repairing electrician to make the best recommendation based upon conditions and budget.

We'll talk next month,

Mike Casey
Kaplan Professional Schools
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