fkelly said:
I'm surprised there is no generally accepted solution.
The wild card, in my opinion, with respect to #12 and #10 gage aluminum branch circuit wiring in dwellings, especially in dwellings "of a certain age" (late Sixties thru early Seventies), is the
perception of risk on the part of the Electrical Contractor examining the job.
Some Electrical Contractors will simply not work on aluminum #12 & #10 branch circuit cables, except to remove them and replace them with copper cables.
The perception is a highly subjective thing and it informs the business decisions behind the nature of the repairs an individual Electrical Contractor will offer to a client.
The type of installation originally done in a given dwelling will also contribute to an Electrical Contractor's evaluation and repair recommendation. The original workmanship and, in particular, box volume calculations (or lack thereof), can be a source of difficulty, difficulty hindering simple repair.
When I apprenticed in the late Sixties, I did a fair amount of new construction electrical for single family dwellings. Some of the dwellings were wired with aluminum, throughout, because of the cost of copper. I clearly remember the "hammer handle" technique of making up three 10/2 NMs in a 16 in? wall case.
Brrrrr-r-r-r-r! I shudder when I think about it.
If I examined that box today, and attempted to install a pigtailed GFCI (it was at the kitchen counter -- GFCIs are not readily available with a CO/ALR rating), I'd have to put a box in with many more cubic inches.
Kind of a set of dominoes falling.
The original assembly conditions lead to the Code condition leads to an eventual solution for a specific assembly.
The original assembly drives the solution. In my opinion, no generalization, other than that, is possible. The fact that aluminum wire was used is only a
part of the problem.
An alternative to rebuilding an assembly is to replace the aluminum branch circuit cable, which, depending upon the labor of the specific installation, may be cheaper than reusing the aluminum.
Given your business, you may wish to interview a couple "aluminum specialist" Electrical Contractors to have on a short list for the occasional problem house. The correct repairs will almost always be "too expensive", and the clients can always get someone else who will tell them what they want to hear, but you won't be the source of the bad information.
