Circuit breaker poles in series connection

[thinker]

Circuit breaker MFG application guide allows the usage of three pole AC molded case CB for DC circuit, and recommends connection of all three poles in series. This connection is very specific: the load side of pole 1 is connected to the line side of pole 2, and the load side of pole 2 is connected to the line side of pole 3. This requires to run wires around the CB.Why not to connect load sides of poles 1 and 2 (short jumper) and line sides of poles 2 and 3 (another jumper)? The MFG technical support insists on usage of their configuration with no explanation. Again, this a DC application (isolated from ground). Could this (MFG) configuration be dictated by arc suppression capability (I mean the same direction of the current for each pole is required)?

 

[davidbeach]

If it wasn't tested your way, there is no DC interrupting rating your way. Probably has to do with magnetic forces in the breaker during fault sensing and interrupting. But, it doesn't really matter why, if the installation instructions give only one acceptable connection there is only one acceptable connection.