Home inspection today revealed that the house is wired with aluminum wiring. It’s a known potential fire hazard so merits more research. There are lots of websites out there but this is the one that the electrician (Electrical Contractors and Design) that I talked recommended regarding Recognizing Aluminum Electrical Wiring.
There are different fixes for the problem but the “best” system, made by Tyco, attaches a copper wire to the aluminum with a special tool. Every outlet, switch and fixture throughout the house has the Amp Copalum applied to it.