Residential furnace circuit

[Mr.electric]

There is quite a few threads out on this and I still feel confused. 422.12 makes it pretty obvious you need a dedicated circuit and 424.4 makes it sound optional. While 422.12 says other than fixed equipment, 424 list central space heating equipment as fixed equipment. Is one of these articles speaking about gas, oil, wood fired equipment. To be honest I’m getting more confused while I write this.

 

[garbo]

Just going by " Residential Furnace circuit ". I spent most of my years as an industrial electrician but since the 1960's all natural gas residential furnaces were on thier own usually a 15 amp circuit . They only time another device or piece of equipment that was on the furnace circuit was a condensate pump for central AC, electronic air cleaner or UV lamp inside of duct work. In my area years ago houses with oil burners always had a toggle switch at top of basement steps and no service switch on natural gas furnaces. Never made sense.

 

[Fred B]

There is quite a few threads out on this and I still feel confused. 422.12 makes it pretty obvious you need a dedicated circuit and 424.4 makes it sound optional. While 422.12 says other than fixed equipment, 424 list central space heating equipment as fixed equipment. Is one of these articles speaking about gas, oil, wood fired equipment. To be honest I’m getting more confused while I write this.

First you need to decide what sort of heating equipment you are using. 422 and 424 are talking about different types of heating equipment.
424 is typical of baseboard electric. 422 typical of a furnace, gas or oil.

While 422.12 says other than fixed equipment

Finish that statement: fixed electric space heating equipment, That is usually your 424 requirements, that is why it is included as an "other than" in 422.12. Hoping to avoid confusion, but you would need to know what your equipment really is.

422.12 restriction to require an individual branch circuit but has exceptions that allow for equipment necessary for operations can be added on that circuit.

424 Limits number of pieces of equipment on a circuit based on loads.

 

[Mr.electric]

I think my confusion is 424.1 scope lists central heating systems as fixed electric space heating equipment. I’m not seeing how 422.13 references what type of equipment it is I.E. gas, oil, water.

 

[mtnelect]

This might help to explain.

 

[Mr.electric]

So if it isn’t strictly electric powered central heating equipment “fixed electric space heating equipment” it’s basically an appliance and held to the rule of 422.12.

 

[mtnelect]

Also, don't forget to hardwire the gas furnace., and 99% of my inspections for CSLB, cords are used.

 

[tortuga]

Just going by " Residential Furnace circuit ". I spent most of my years as an industrial electrician but since the 1960's all natural gas residential furnaces were on thier own usually a 15 amp circuit . They only time another device or piece of equipment that was on the furnace circuit was a condensate pump for central AC, electronic air cleaner or UV lamp inside of duct work. In my area years ago houses with oil burners always had a toggle switch at top of basement steps and no service switch on natural gas furnaces. Never made sense.

I remember those safety control switches for oil burners also, they fell under 724.31 [formerly 725.31] so we had to wire with BX or later MC or EMT.

 

[letgomywago]

I remember those safety control switches for oil burners also, they fell under 724.31 [formerly 725.31] so we had to wire with BX or later MC or EMT.

That makes sense. I'd see old school BX on a old oil furnace that was swapped out to gas quite often and thought it was a bit odd but whatever. This would be in a house that was all ungrounded romex or KnT.