My new house is done being built and I am going to come in and install my new gas range and dishwasher, both 120V 15A appliances.
I got thoroughly confused looking at the breaker box because gas range and dishwasher were labeled on different circuits but at the breaker the electrician installed a double pole breaker. I traced the two ungrounded conductors to two separate wires coming out of the box, telling me it is really two separate circuits(EDIT: On second thought I did see a red wire in the one end so I must not have traced that right. It probably is going to one 14/3 cable now that I think about it).
Clearly if the gas range or the dishwasher were to trip the breaker then it immediately trip the other circuit as well. I am curious why it was done this way.
Is this a new NEC code that I am unaware of? Could this be a regional code of some kind? Are there any safety concerns for why the electrician decided to do this over using two separate 15A breakers?
Best Answer
I'm guessing the circuits are sharing a neutral, and so are considered a multiwire branch circuit.
In the 2008 version of the National Electrical Code (NEC), they introduced sub section (b) to section 210.4. This sub section covers the disconnecting means of a multiwire branch circuit, and requires a simultaneous disconnect of all ungrounded conductors.
This subsection can be satisfied by using a multipole breaker, which provides both simultaneous trip and simultaneous disconnect. The subsection can also be satisfied by simply attaching handle ties between multiple single pole breakers, which would provide simultaneous disconnect (and may or may not provide simultaneous trip).