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Does a gas furnace require a dedicated circuit?

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Coppersmith

Coppersmith

Senior Member
Location
Tampa, FL, USA
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Electrical Contractor
The closest reference I have found is: 422.12 Central Heating Equipment. Central heating equipment other than fixed electric space-heating equipment shall be supplied by an individual branch circuit. I think this is for electric equipment. The gas furnace draws no more than 3 amps. I want to connect it to the conveniently located garage circuit (with a disconnect of course).
 
H

HEYDOG

Senior Member
Coppersmith said:
The closest reference I have found is: 422.12 Central Heating Equipment. Central heating equipment other than fixed electric space-heating equipment shall be supplied by an individual branch circuit. I think this is for electric equipment. The gas furnace draws no more than 3 amps. I want to connect it to the conveniently located garage circuit (with a disconnect of course).
Click to expand...
Gas furnace is central heating equipment. Needs to be
on an individual branch circuit!
 
kwired

kwired

Electron manager
Location
NE Nebraska
Occupation
EC
wwhitney said:
Use a fused disconnect and now it is an individual branch circuit.

Cheers, Wayne
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It must be rated as a branch circuit overcurrent protection device.

Typical "safety switch" is rated as a branch circuit overcurrent protection device.

Typical "box cover unit" such as SSU is not rated as a branch circuit overcurrent protection device.
 
Dennis Alwon

Dennis Alwon

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Staff member
Location
Chapel Hill, NC
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Retired Electrical Contractor
wwhitney said:
Use a fused disconnect and now it is an individual branch circuit.

Cheers, Wayne
Click to expand...

I don't buy that and I doubt any inspectors would either.

If the op is talking about the garage receptacles then they would have to be on their own circuit but that gets sticky anyway based on it being an existing installation.

So now you are taking a branch circuit and making it a feeder. How can the garage outlets be on a feeder and not a branch cir. You can't make it a feeder in one case and a branch circuit in another. It seems a bit too much for me
 
kwired

kwired

Electron manager
Location
NE Nebraska
Occupation
EC
Is said "furnace" intended to have ducts connected to it to convey air in/out of the unit to other locations? That is central heating equipment IMO.

If this is just a unit heater I wouldn't call it central heating equipment.
 
W

wwhitney

Senior Member
Location
Berkeley, CA
Occupation
Retired
Dennis Alwon said:
I don't buy that and I doubt any inspectors would either.
Click to expand...
kwired has it right, if the fuses and fuse holder are listed as branch circuit OCPD, then they create a branch circuit.
Dennis Alwon said:
So now you are taking a branch circuit and making it a feeder. How can the garage outlets be on a feeder and not a branch cir.
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Based on the definitions, the same piece of wire can be a feeder with respect to one outlet, and a branch circuit with respect to another. The two terms are not mutually exclusive.

Cheers, Wayne
 
C

curt swartz

Electrical Contractor - San Jose, CA
Location
San Jose, CA
Occupation
Electrical Contractor
Coppersmith said:
The closest reference I have found is: 422.12 Central Heating Equipment. Central heating equipment other than fixed electric space-heating equipment shall be supplied by an individual branch circuit. I think this is for electric equipment. The gas furnace draws no more than 3 amps. I want to connect it to the conveniently located garage circuit (with a disconnect of course).
Click to expand...
Why would a gas furnace not be considered central heating equipment?

Do you have a make and model of the furnace? I have never seen a gas furnace with that low of an amp rating. I just looked up several makes and models. The smallest units show a minimum capacity of 8-9 amps. Those units also state MOCP of 15 amps.
 
Ponchik

Ponchik

Senior Member
Location
CA
Occupation
Electronologist
AC\DC said:
article 100 Branch circuit, definition.
Click to expand...
Ponchik said:
Ofcourse👍👍
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wwhitney said:
Use a fused disconnect and now it is an individual branch circuit.

Cheers, Wayne
Click to expand...
So I looked in the definitions and I am still confused as to how your suggestion will be OK. Based on what you said, I can install a fused disconnect anywhere on a branch circuit and all wiring past that fused disconnect is a branch circuit?

What do you call the existing wiring that feeds the new fused disconnect?
 
Ponchik

Ponchik

Senior Member
Location
CA
Occupation
Electronologist
wwhitney said:
kwired has it right, if the fuses and fuse holder are listed as branch circuit OCPD, then they create a branch circuit.

Based on the definitions, the same piece of wire can be a feeder with respect to one outlet, and a branch circuit with respect to another. The two terms are not mutually exclusive.

Cheers, Wayne
Click to expand...
So a feeder can be either/or and at the same time both?
 
W

wwhitney

Senior Member
Location
Berkeley, CA
Occupation
Retired
Ponchik said:
So a feeder can be either/or and at the same time both?
Click to expand...
Apparently that is a logical consequence of the wording of the definitions.

With respect to any given outlet, there is a clear delineation between branch circuit and feeder, and there is only one "final overcurrent device" for that outlet. However, that delineation can vary depending on which outlet you consider.

Cheers, Wayne
 
L

letgomywago

Senior Member
Location
Washington state and Oregon coast
Occupation
residential electrician
In the end just do a circuit. If it is permissible it isn't standard to share that circuit for the past 80 years. 15 amp circuit is cheap I use it to feed the condensate pump anyway so it'll get use even if it's lightly used. Maybe go for that 10 amp 15awg copper clad in the future.
 
kwired

kwired

Electron manager
Location
NE Nebraska
Occupation
EC
curt swartz said:
Why would a gas furnace not be considered central heating equipment?

Do you have a make and model of the furnace? I have never seen a gas furnace with that low of an amp rating. I just looked up several makes and models. The smallest units show a minimum capacity of 8-9 amps. Those units also state MOCP of 15 amps.
Click to expand...
That low amp rating is part of why I asked if it really is a "furnace" or if it is maybe a "unit heater".
 
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