Identify - old house breaker or what?

[w5hro]

Just picked up this old knife switch box in an antique shop down in Santa Barbara yesterday.

The tag said it was an old circuit breaker maybe for a house. It has a glass cover that comes off via two twist nuts.  

Anyone ever seen or remember these? I thought I might use it to switch my antenna with the open wire line (ladder line) out into the garage.

[W7TFO]

Is a cutout device from a 3-phase commercial electrical meter panel.  Used to isolate each phase E & I  from CT's and PT's into the kWh meter. 

Still in use, most modern ones are really crappy.   Your older one is a cool switch for many uses.

73DG

[N4LTA]

Yep - The switches keep the CT (current transformer) shorted while they are out of the meter circuit.

Otherwise you get an extremely high voltage when the CT tries to pump current through the open circuit - alot like a modulation transformer working into no load.