I have recently checked some houses in Elgin with a common builder and the under-sink receptacle for the dishwasher and disposal was a split duplex receptacle with a dedicated circuit for each appliance. This setup was protected by a 2 pole tied circuit breaker. When I questioned the electrical inspector he cited the 2008 NEC code for multiwire branch circuits, saying a common neutral wire required the 220v breaker.
It still seems to me that there would be a potential failure to trip if there was a problem on one appliance. Any comments?
Mark Kollath
Mark Kollath Home Inpection, Inc.
Chicago
It’s required. Under the 2008 it’s required for all MWBC’s, circuits with shared neutrals. In this instance it was required for many years prior to the 2008 code change since there are two circuits on the same yoke.
Circuit breakers are designed to trip internally. Even if the handle is held in the closed position the breaker will still trip. As Roy mentioned this was added to the 2008 NEC for the safety of someone working on the circuit with a shared neutral. Shared neutrals can be dangerous if they’re opened with only one of the circuits turned off.
If there was a fault situation in one of the circuits why would the other circuit need to open? Even a listed handle tie might not open the other breaker.
Correct me if I’m wrong, but the breakers trip without regard to the handles. The tie is only so one cannot be independantly operated without the others at the same time.
*Edit… *OK I just reread the thread, and think I got the answer to my own question.
In Canada, kitchen counter split receptacles have been protected this way since the 1970’s. Although there have been code changes since then requiring single circuit GFCI protected receptacles near sinks, the present code still allows split receptacles protected by double-pole “tied” breakers away from sinks.
There appears to have been no problems with this arrangement.
Someone posted a photo of a breaker a while back where Harry Homeowner had tried to “fix” a breaker that kept tripping by jamming a stick up against the breaker handle inside the panel … :shock:
It didn’t work of course because of the internal trip mechanism of the breaker. But ya have to give him credit for really trying to kill himself. Wish I could find that photo/topic again. It was priceless!