How to know when tandem breakers can be used A tandem circuit breaker, also known as a double pole circuit breaker, takes up the space of a single circuit breaker on a Square D panelboard.

Appropriate for a two-pole 20-amp breaker or a single-pole 30-amp breaker. 8-gauge or 6-gauge wire Used for 40-, 50- and 60-amp two-pole breakers; large appliances. Also used to serve subpanels.