This is in the top ten Code changes for 2011. I hear the stories about being ZAPPED off the neutral on a multi-wire branch circuit, being zapped is lucky! It is the ones that have been electrocuted that were not so lucky to be just ZAPPED. So after years of hearing these stories it has become a Code requirement. This used to be a requirement when we had two circuit attached to one device such as a receptacle or equipment so in 240.15(B)(1) it permits the use of single pole breakers with identified handle ties to be used in lieu of a two pole or three pole breaker.
210.7 was formerly divided into two sections parts A and B. Section 240.15(B)(1) also requires that when used, single pole circuit breakers with handle ties (identified) SHALL BE permitted to be used to protect a multi-wire branch circuit. So one question that comes to mind can two Arc Fault breakers be used in this manner? I have had some who said that the AHJ did not allow this practice because it was not listed! Does this section give us some relief when using this practice. A certain manufacturer has an informational manual that shows using two single pole Arc
Faults in this manner for a multi-wire branch circuit.. That paper can be found in one of my other weekly columns, on this web site.
When working in the field and you pull a common neutral for a couple (multiple) of branch circuits you have to be able to disconnect the circuits at that same time (simultaneous). This would require a two pole or three pole circuit breaker to be able to accomplish this feat. You may use identified handle ties on single pole circuit breaker to make this happen. The intent of this section has been around for a long time, but in my daily inspections I still have to issue a correction notice for this practice. I find it more often in housing and it is usually easier to find when the contractor runs a 3 wire branch circuit(black white and red wire). Any time you run a 3 wire branch circuit in a residence it requires a common trip circuit breaker at the point at which the branch circuit originates, the panel. There are no exceptions!
210.7 Multiple Branch Circuits. Where two or more branch circuits supply devices or equipment on the same yoke, a means to simultaneously disconnect the ungrounded conductors supplying those devices shall be provided at the point at which the branch circuits originate.
So as you can see I find it all the time, there are several circuits tied together in this manner in this one panel. The ones with the wire through them may trip one circuit but it may not trip them all. So when you wire residences remember that all multi-wire circuit need to be on a common trip breaker even Arc Faults.
Till next week be safe
Jake