It has been a while since I put in a shunt-trip ... but if I recall correctly ...
The breaker took up three spaces. Two had large lugs, and were clearly for the panel feed. The third had a much smaller lug, and was for the wire to the 'kill' switch. The other side of the switch went to the neutral buss.
I was under the impression that closing the switch created a dead short, tripping the breaker. It sure sounded that way! I have since been corrected, and that there actually is a mechanism inside that operates ... a 'load,' as it were.
