By D. A. (Midwested) on Saturday, September 8, 2018 - 12:35 pm:
jbuck,
That mailbox shaped enclosure is protecting a rotary electrical switch that is activated by the handle. You can see the wires for each leg of the switch exiting the back. The wires go to a bunch of things on the wall that sort of look like little radiators. These are actually large power resistors. The resistors are used as a load to either test or control electrical machinery. The rotary switch will eventually wear out and break but when it does it usually produces lots of arcing and sparking so the "mailbox" enclosure helps protect the operator.
I'm glad you enjoyed the photos.
By jbuck (Jbuck) on Sunday, September 9, 2018 - 09:03 am:
Thanks for the excellent explanation D. A.
(Midwested)! The whole smelter is fascinating; would
be great to take the tour.