Another potential reason to use specific pole combinations is when putting two contacts in series to obtain a higher interrupting or withstand voltage value for the switch. Particularly when trying to increase DC interrupting voltage.I seem to remember seeing in the instructions for a 3 pole disconnect switch that when doing this you must use the 2 outer poles of the switch. Might have been specific to that manufacturer.
Supplier told me that on some fusible and non-fusible safety switches the demand is so low for the 2 pole style the manufacturer just supplies 3 pole when a 2 pole is requested and 2 pole versions are not available.
For anything other then 225 amp and less @ 240 volts I can agree. There are a lot of 2 pole 240 volt breakers out there of smaller frame sizes.kind of like 2 pole MCCB. It is usually less expensive to just buy a 3 pole breaker and usually a lot faster too.
I seem to remember seeing in the instructions for a 3 pole disconnect switch that when doing this you must use the 2 outer poles of the switch. Might have been specific to that manufacturer.
Supplier told me that on some fusible and non-fusible safety switches the demand is so low for the 2 pole style the manufacturer just supplies 3 pole when a 2 pole is requested and 2 pole versions are not available.
I ordered some 2-pole Eaton disconnects once that came labeled as 2-pole, but were actually 3-pole with a jumper wire from line-2 to load-3.