I have a GE model 9L15C "Valve Type Secondary Lightning Arrester" as pictured here:
[Linked Image from 65.108.216.53]

It has two black conductors (14AWG) and one white (14AWG). As per the notice printed on the unit itself, the white conductor is connected to ground and the two black conductors are connected to a separate breaker each. The breakers are connected via a handle so that if one trips, the other does also.

The only information I can find on the GE website is for "GE Tranquell Surge Arrestors" which appear similar:
[Linked Image from 65.108.216.53]

Is anybody familiar with these? I'm a bit confused in that:

1. It connects to breakers in such a way as to indicate the unit itself is being protected--yet it is supposed to be a lightning arrestor. (It's not connecting between the line side and load side, but exclusively on the load side.)

2. Apparently, there is no way to test the unit, so how to know if it still works [Linked Image]

3. If it uses 14AWG conductors, should it not be on a 15A breaker rather than 20A?