Air handlers - once again

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Dennis Alwon

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What code number do you wish to use ? Not this

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.

Yes, that. I stated that quite plainly in the earlier post. I still think it should apply.
 

Dennis Alwon

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It is not HEATING. NEC never tries to save on words. Had they meant it to say

"422.12 Central Heating and cooling Equipment " they would have.
So if this were a gas furnace you would say a separate circuit is required but take away the heat and what difference does it make it terms of the circuit. I know what the words state but why would it be different.
 

Jim W in Tampa

Senior Member
Location
Tampa Florida
So if this were a gas furnace you would say a separate circuit is required but take away the heat and what difference does it make it terms of the circuit. I know what the words state but why would it be different.

Personally i don't think it changes anything but we are stuck with what NEC says. We do not need to agree with NEC just forced to follow. It is like speed limit signs.
 

tonype

Senior Member
Location
New Jersey
Just to clarify the system configuration:

Boiler supplies baseboard convectors - totally separate system from cooling. Cooling air handlers only have fan and cooling coils - no hot water heating coils or electric strip heaters. Only used in the summer for cooling.
 

kwired

Electron manager
Location
NE Nebraska
Just to clarify the system configuration:

Boiler supplies baseboard convectors - totally separate system from cooling. Cooling air handlers only have fan and cooling coils - no hot water heating coils or electric strip heaters. Only used in the summer for cooling.

440.3(B) says:

The rules of Articles 422, 424, or 430, as applicable, shall apply to air-conditioning and refrigerating equipment that does not incorporate a hermetic refrigerant motor-compressor.

The unit is a motor operated appliance and must meet requirements in 422 and in 430, no heat strips leaves 424 out of the picture.
 

Jim W in Tampa

Senior Member
Location
Tampa Florida
Only violation i see is your breaker is higher than name plate. Will it work sure if they don't add up to more than 20 amps. Is it legal no. Would i fix it if money comes out of my pocket NO.
Now if your inspecting for the buyer they might be smart to demand it fixed for simple reason that someday they might be the sellers and end up paying to fix.
I see no real safety issue here.
 

iwire

Moderator
Staff member
Location
Massachusetts
So if this were a gas furnace you would say a separate circuit is required but take away the heat and what difference does it make it terms of the circuit. I know what the words state but why would it be different.

I don't know that it makes any diffrance but it says what it says and IMO an inspector could not use that section on cooling equipment.

BTW, most office spaces have multiple heating cooling fan boxes supplied from one circuit. :cool:
 

Dennis Alwon

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Location
Chapel Hill, NC
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I don't know that it makes any diffrance but it says what it says
Yeah, I know... trying to make sense of it. Why would this rule exist for heating and not for cooling. The only reason I can think of is that you wouldn't want 4 or 5 systems to loose heat at the same time when there is only an issue with one unit. Heat is generally more necessary than cooling. It appears we can survive easier without cooling than we can without heating.
 

iwire

Moderator
Staff member
Location
Massachusetts
Yeah, I know... trying to make sense of it. Why would this rule exist for heating and not for cooling.

My question is why does this rule exist at all. The NEC already covers proper sizing of circuits.


The only reason I can think of is that you wouldn't want 4 or 5 systems to loose heat at the same time when there is only an issue with one unit.

It gets tricky, as to me if you have 4 or 5 systems you do not have 'central' heating at all.
 

kwired

Electron manager
Location
NE Nebraska
The only reason I can think of is that you wouldn't want 4 or 5 systems to loose heat at the same time

I would think that would be a design issue or an issue with some other code and not the NEC.

IMO, NEC should only care about if there is a direct threat to life or property from the electrical supply to the unit. If there is another code wanting more than one circuit to prevent total loss of heat then NEC could have a FPN to reference it.
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
I would think that would be a design issue or an issue with some other code and not the NEC.

IMO, NEC should only care about if there is a direct threat to life or property from the electrical supply to the unit. If there is another code wanting more than one circuit to prevent total loss of heat then NEC could have a FPN to reference it.

I was just looking for some reason for art. 422.12. It doesn't make sense esp. in lieu of it not referencing air handlers that only move cool air. :-?
 
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