Tandem Circuit Breaker Wiring Diagram. Turn off (o) the circuit breaker. Use an electrical tester by putting the tip of one probe against the ground bus bar and the other against one of the screws of a circuit breaker.

The only catch to this is that nec states that breakes can only be loaded to 80% capacity of there rated amperage, so a 15 amp breaker is limited to 12 amps an a 20 amp breaker is limited to 16 amps Tighten all electrical connections to specifications. Siemens qp 20 amp 2 pole gfci circuit breaker in the breakers department at lowes com.