Why are there four wires for connecting a QJ shunt trip instead of the two wires used for all other circuit breaker shunt trips?
The QJ breaker is an older style that has a separate coil clearing contact instead of having the contact built into the shunt trip unit itself. Therefore, there are four wires, two for the coil and two for the aux contact. These are wired in series per the diagram included with the shunt trip or in the QJ instruction manual.
