On Sat, 4 Apr 2015 00:52:07 -0700 (PDT), whit3rd
wrote:

On Friday, April 3, 2015 at 9:23:59 PM UTC-7, 2phar wrote:

There are seven of these sockets within a 1964 built house in Michigan USA:

"http://i60.tinypic.com/2628481.jpg"

That's a two-pin Jones plug. General purpose connectors, not approved for
household AC power, nor intended for RF. So, speaker wiring seems likely.
Hams used to use them for 12v DC so maybe someone used them to power
radios and other 12V equipment and have it all backed up by a 12V car
battery somewhere. As others have said, though, they could be for
anything - speakers, etc.