I did find this...
http://ecmweb.com/content/think-gfci"GFCI receptacles can be used on multiwire circuits, but they must be wired such that the neutral on the load side of the GFCI is not shared by two ungrounded conductors. Failure to observe this requirement will result in a differential current any time a load served by an ungrounded conductor not connected to the GFCI is energized, immediately tripping the GFCI.
Note that multipole GFCI circuit breakers are available for use on multiwire circuits. The GFCI sensor mechanisms in these breakers operate on the same principle as the GFCI receptacle, except that the current from all ungrounded conductors and the neutral pass through the "adding machine." As in the case of the receptacles, the unit will trip when it detects unbalanced current over the 4mA to 6mA trip range."Not sure if the breaker I used is a true multi-pole, the 120/240v seems like it is.
Last edited by Trick440; 08/18/16 09:52 PM.
