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#101133 - 02/12/07 05:26 AM Furnace Wiring
George Little Offline

Registered: 01/18/04
Posts: 1492
Loc: Michigan USA
What would you say to a contractor about his hook up on a furnace when he used a cord and cap connection instead of a direct hard wire connection?
Cord and cap connection is suitable if the horsepower rating is proper and the gauge of wire in the cord is adaquate.
The only thing I was concerned with is the manufacturer's installation instructions.
I have seen "wall heater" type installations that came out with a cord installed but I have never seen anyone connect a furnace using a cord and cap connection.
George Little

2014 / 2011 NEC & Related Books and Study Guides
#101134 - 02/12/07 06:03 AM Re: Furnace Wiring
resqcapt19 Offline

Registered: 11/10/00
Posts: 2209
Loc: IL
I think that you have a 400.8 violation.

#101135 - 02/12/07 10:11 AM Re: Furnace Wiring
renosteinke Offline
Cat Servant

Registered: 01/22/05
Posts: 5305
Loc: Blue Collar Country
I think you have a typical "west coast" furnace installation. This is especially common where the electric is only needed for the igniter and the blower.

#101136 - 02/12/07 11:29 AM Re: Furnace Wiring
scameron81 Offline

Registered: 02/24/04
Posts: 80
Loc: Healdsburg, ca, USA
Out here in California you would be hard pressed to find a furnace that wasn't installed like that. Usually the only time the furnaces are hardwired is in commercial applications.

#101137 - 02/12/07 12:33 PM Re: Furnace Wiring
iwire Offline

Registered: 01/05/03
Posts: 4343
Loc: North Attleboro, MA USA
What about 422.16?

The furnace would have to be intended or identified for cord connection.

I also have a hard time believing a furnace needs 'frequent interchange.

The fact that California allows it does not mean it is indeed NEC compliant.

There are things we do here in MA that would not fly in other states.
Bob Badger
Construction & Maintenance Electrician

#101138 - 02/12/07 07:49 PM Re: Furnace Wiring
George Little Offline

Registered: 01/18/04
Posts: 1492
Loc: Michigan USA
Don- I agree with you on the 400.8 violation. I think unless there is some reason to connect it with a cord/cap they would specify same in the manufacturers installation guide.

And Bob- I would not think that a furnace as installed with duct work and piped in gas line qualifies for 422.16

So with you two guys backing me up- I'm Golden
George Little

#101139 - 02/12/07 08:15 PM Re: Furnace Wiring
BigB Offline

Registered: 03/31/04
Posts: 727
Loc: Tucson, AZ USA
Here in Arizona virtually all the gas furnaces are plug and cord also. The only requirement is the receptacle must be the fused type, with an Edison fuse sized to Article 430.

Our evaporative (Swamp) coolers are also plug and cord connected, right up there on the roof, using a Midwest fused box sort of like a giant bubble cover where the cords hang out the bottom, one for the motor and one for the pump.

And yes, some of our homes are made out of mud.

#101140 - 02/12/07 09:01 PM Re: Furnace Wiring
EV607797 Offline

Registered: 10/25/06
Posts: 756
Loc: Fredericksburg, VA, USA
I know that this is kind of a stupid question, but would an electric furnace in a heat pump situation installed out west be wired with a cord and cap as well? An example would be a 50 amp range cord used for a few backup heat strip units for the inside air handler. Around here in the eastern U.S., all furnaces, regardless of fuel, are hard-wired.

"But the guy at Home Depot said it would work."

#101141 - 02/13/07 06:42 AM Re: Furnace Wiring
renosteinke Offline
Cat Servant

Registered: 01/22/05
Posts: 5305
Loc: Blue Collar Country
No, such a heat pump would not be wired using a cord and cap.

The justifications for using cords here are a) the need to service the equipment;
b) the desire to have a receptacle available to the serviceman; and,
c) 430.109(F) recognizes that motors might be cord and plug connected, without making any restrictions as to the conditions under which this may be done.

That last reference, to 430.109(F), is not as clear as it once was. Prior editions to the code clearly stated that such "shall be permitted." The closing reference to portable motors "under 1/3 hp" not needing a horsepower rated rated plug has been the basis for limiting application of the cord & plug as a disconnecting means has been used to justify limiting this method to small motors in practice.

So, out West, one will often find fixed appliances hooked up using cord & plug, especially when the appliance can be served by an 'ordinary' 120v/15a receptacle. We will use pigtails on dishwashers, disposals, trash compactors, air cleaners, air conditioning condensers, circulation pumps, and all manner of things that "back East" might be hard-wired.

Taking the word-wrangling out of the discussion, I like the cord connection mainly because it provides a simple and sure means of disconnecting what you're working on. No more hunting for breakers! It also recognizes that the 'other trade' is not likely to be there at the same time as I; I can provide the receptacle, and he can put in his stuff.

That said, even I have some issues with this cord & plug connected furnace:

#101142 - 02/13/07 09:18 AM Re: Furnace Wiring
SteveFehr Offline

Registered: 03/19/05
Posts: 1192
Loc: Chesapeake, VA
I don't see how this is a violation of 400.8. The cord is NOT substituting "fixed wiring of a structure" because it is connecting a serviceable appliance to an outlet. None of the other restrictions in 400.8 apply; this installation isn't trying to skirt cable routing rules, it's just using a plug instead of hardwired conection at the outlet box.

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