[Shop-talk] Aluminum and copper wiring

[Randall]

> Hi guys.  I am currently visiting my sister-in-law and offered to install
> a light switch for her; she has dusk-to-dawn outdoor lights that were
> installed by a handyman and wired without a switch.  She'd like to be able
> to turn them off, which is normally a pretty simple job.  However, her
> house was built in the early 70's and has mostly aluminum wiring.

You might want to talk to her about the advantages of having the aluminum
ripped out.  Old aluminum wiring is substantially more likely to start a
fire than copper.
http://www.kinginnovation.com/pdfs/alumiconn-docs.pdf

> I know using a CO/ALR outlet allows me to connect the (copper) light
> circuit to the original (aluminum) circuit, but I am not sure about how to
> do the ground wires.  I assume it is less critical with a ground wire than
> a hot one, but still.. I suppose I could simply not ground the lights or
> the new switch, but I am wondering if there is a better solution.

There are special purple wire nuts that are approved for joining copper
directly to aluminum.  Still not a great solution IMO, but certainly better
than leaving the circuit ungrounded.  A drop of Noalox wouldn't hurt either.
https://goo.gl/4GmeCC

-- Randall