Beginning with the 2008 NEC all MWBC must have a means to disconnect all ungrounded conductors simultaneously. This may be done with multi-pole circuit breakers or with individual circuit breakers with handle ties. There is no requirement to retrofit installations done prior to the code changes.I see over and over on this board where dual circuits with a common neutral need to be on a 2-pole breaker. I knew this was required for circuits where both circuits are used on a common strap in a wall outlet, but was unaware of the requirement on all circuits which use a common neutral. Can anyone tell me the NEC code where this is required and when this started to be required.
I prefer seperate feeds for each circuit, but have several of these that may be "grandfathered" in my house.