Originally Posted by smac999
no they are not the same. they are intereconnected internally as well as externally. you can't just buy 2 singles and join the handles.
The typical marine
circuit breakers such as Blue Sea devices have no internal interconnections. The photo
below is a similar desgin.
Common trip breakers
Three-pole common trip breaker for supplying a three-phase device. This breaker has a 2 A rating
When supplying a branch circuit with more than one live conductor, each live conductor must be protected by a breaker pole. To ensure that all live conductors are interrupted when any pole trips, a "common trip" breaker must be used. These may either contain two or three tripping mechanisms within one case, or for small breakers, may externally tie the poles together via their operating handles. Two-pole common trip breakers are common on 120/240-volt systems where 240 volt loads (including major appliances
or further distribution boards) span the two live wires. Three-pole common trip breakers are typically used to supply three-phase electric power
to large motors or further distribution boards.
Two- and four-pole breakers are used when there is a need to disconnect multiple phase AC, or to disconnect the neutral wire to ensure that no current
flows through the neutral wire from other loads connected to the same network when workers may touch the wires during maintenance
. Separate circuit breakers must never be used for live and neutral, because if the neutral is disconnected while the live conductor stays connected, a dangerous condition arises: the circuit appears de-energized (appliances don't work), but wires remain live and some RCDs
may not trip if someone touches the live wire (because some RCDs need power to trip). This is why only common trip breakers must be used when neutral wire switching is needed.