Last question: Is any other equipment allowed on a circuit used for central heating equipment? If so what?
These questions (four questions) I've posted today are assigned to me as a code panel member at our next IAEI seminar held in Michigan. I appreciate your inputs and code references and will be used as part of my research and consensus. Names will be withheld to protect the innocent.
422.12 Central Heating Equipment. Central heating equipment other than fixed electric space-heating equipment shall be supplied by an individual branch circuit. Exception No. 1: Auxiliary equipment, such as a pump, valve, humidifier, or electrostatic air cleaner directly associated with the heating equipment, shall be permitted to be connected to the same branch circuit. Exception No. 2: Permanently connected air-conditioning equipment shall be permitted to be connected to the same branch circuit.
I have seen where some AHJ's require the smokes to be on the heating circuit. They claimed that the homeowner would not be able to turn off the circuit in case the smokes went into alarm. This also happened to be before there were AC/Dc smokes.
Greg nailed it. The one that I'd forgotten about was the "Permanently connected air-conditioning equipment" has anyone ever dealt with this? To me a window shaker w/cord would not be considered "permanently connected".
You know .... I don't have the documentation in front of me ... but that code provision sounds a lot like my writing .... it might have come from one of my proposals.
There was a time when some folks, especially at certain other "inspection" forums, would get all huffy if they found a circuit with a selector switch supplying both the heat and the AC. Or, if they found a duplex receptacle supplying the furnace, or if the humidifier built onto the furnace was powered by the same circuit, etc.
The NEC 'dedicated' circuit requirement comes after decades of the requirement only being found in the Mechanical code.
One inspector in the area would not allow any part of an receptacle at a furnace for pumps,etc. to be left un-used. His reasoning was that the homeowner could plug a refridgerator or similar appliance into the un-used part of the receptacle.
I read that to be a central air conditioning system that shares the air handler with the furnace. If they are interlocked, they can live on the same circuit and in that case the A/C is the big load and the furnace is the small load. (unless you have toaster wire heat strips, that passes for a furnace here). If you put a mini-split that was not interlocked with the furnace, on that circuit, I would have a problem with it.