I was called to fix / clean up / wtc. the wiring left behind when an industrial space changed tenants.
Atop the restroom - where the panel was located - I found this fine collection of electrical hardware. It contained the circuits for the phone, shop receptacles, bath fan, and furnaces. The plug serves the igniter for the water heater:
Now, in taking it apart, I discovered something I had missed at first clance. Look at this close-up:
That's right: coming out of the box, and before the pulling ell, is a mysterious hex shape. It turned out that they had used a 'jake' (connector for flex) as a means to directly connect the ell to the box!