No disrespect, doc, but multi-wire circuits are a fact of life. Especially by professionals. It is often amateurs who will run unnecesary neutrals. It is certainly safer to run the extra neutrals, but the reality is this requires larger conduits & boxes. The key is to be aware of multi-wire circuits. (That being said, I'll probably get hit again someday!!) As far as the 40A brkr, a screw-up,indeed.
GFCIs have no problems with line side multiwire circuits. The only GFCI that will work with a load side multiwire circuit is a 2 pole 120/240 volt breaker. Don(resqcapt19)
