Seen recently in Boulder, Colorado.
If you look closely at the photo, there is a wire coming out of the bottom of the device. My guess is it is used to take some power off of the line and send it somewhere else, possibly for lightning safety or measuring, as in @Voltage Spike's answer.
Similar looking cable seen on the left:
It's probably one of these things:
- Lightning arrester - Used to turn on when the voltage get's too high and send the excess voltage to ground
- Fuse - probably not a fuse because it
- Current/Voltage measurment device
- Switch or circuit breaker.
I think it is most likely a current measuring device, because it has what looks like a resistor and the two orange arms are most likely to measure a differential voltage. The comm line goes out the bottom.
whilst theoretically an option the shape is very odd for it to be a lightning arrester...as it's connected in parallel to the line i would argue that it can't really be a fuse or HV contactor either. whilst measuring current via a shunt is theoretically possible given that the impedance of the u-shaped thingamajig is lower than the one of the main lines impedance it is very unusual to do so. inductive is preferred for a lot of reasons. It could of course be that it is a DC Line, if so it's probably a current sensor, if not then my best guess would be a small instrument transformer for voltage measurement. Can't say anything for sure but that would be my highly uneducated guess. Feel free to correct me if I'm wrong about anything