422.12 exception 2

[Kessler4130]

Title basically says it all, is this article infact stateing that I can supply a AC unit and Furnace on the same branch circuit "if by chance both name plate ratings were comparable ?" I never really noticed thise article............


I may be misinterpreting this entirely, please let me know your view on this article.


Please keep in mind I am no HVAC guy, so I do not know the entire mechanics of an HVAC system, I just find it odd they would allow both on the same circuit even though both loads shouldn't be on at the same time.

 

[Kessler4130]

No one is gonna touch on this ? I will post the exact article maybe that will help . I have no intentions of doing anything like this, and honestly have never seen a situation where it would be practical or even possible. However I still would like to know the exact intention of this article.

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. 2: Permanently connected air-conditioning equipment shall be permitted to be connected to the same branch circuit.

 

[mdshunk]

The only time that I can remember taking advantage of that was when I used the 15 amp, 120 volt circuit that was supplying a central heating steam boiler to also supply the AHU of a split system air conditioner. I only did so because the 4 circuit fuse box was (over)full, and the alternative would have been more than I knew the customer was capable of spending. This is a new '05 exception, as memory serves.

 

[iwire]

In my opinion when they say

Permanently connected air-conditioning equipment shall be permitted to be connected to the same branch circuit.

They are not taking about an air conditioning compressor.

IMO they are taking about any equipment that conditions the air.

Humidifiers, De-Humidifiers, electronic air cleaners etc.

 

[mdshunk]

In my opinion when they say

Permanently connected air-conditioning equipment shall be permitted to be connected to the same branch circuit.

They are not taking about an air conditioning compressor.

IMO they are taking about any equipment that conditions the air.

Humidifiers, De-Humidifiers, electronic air cleaners etc.

In that case, that's been happening for decades.

 

[iwire]

In that case, that's been happening for decades.

Exactly, it gives permission to what would be done anyway. :wink:

At least that is how I see it, I certainly could be wrong.

 

[Kessler4130]

Now we are getting somewhere, but it should be worded better if that is thier intention. Because most auxiliary equipment I have installed was cord and plug connected, not "permanent", so word for word it sounds if they have intentions of letting you put a compressor on the same circuit as the furnace. That is ofcourse if neither piece of equipment clearly states the requirement of a seperate circuit.

I appreciate the input, and am curious what my inspectors say when I ask them.

 

[mdshunk]

Exactly, it gives permission to what would be done anyway. :wink:

At least that is how I see it, I certainly could be wrong.

I see those air cleaners and such covered in exception #1 more clearly. The code has traditionally used "air conditioning equipment" in places where "comfort cooling equipment" would have been more accurate. Perhaps they are being purposely vague to allow the connection of anything at all that has to do with the air in the building.

 

[mdshunk]

. Because most auxiliary equipment I have installed was cord and plug connected, not "permanent", .

In my mind, the fact that a piece of equipment has a cord and plug does not make it "non-permanent". It is simply there to permit efficient interchange. A humidifier, an ozone generator, and an electronic air cleaner are certainly intended to be permanent, although they are often cord and plug connected. A portable dehumidifier, such as are common in basements and often plugged into receptacles on the furnace supplied by the furnace circuit, is not permanent. This portable dehumidifier is certainly air conditioning equipment, but not permanent.

 

[iwire]

I see those air cleaners and such covered in exception #1 more clearly.

Your right.

I have to start bringing my 2005 in from the truck.

I am trying to figure out what kind of AC equipment they are talking about that could be doubled up on the same circuit as a central heating unit.

 

[mdshunk]

I am trying to figure out what kind of AC equipment they are talking about that could be doubled up on the same circuit as a central heating unit.

Would you agree that my example of my connection of a 120 volt air handler to the circuit that supplies 120 volt control power to a steam boiler an example that would be covered under exception #2?

 

[wireman3736]

In an existing motel that had baseboard hot water heat, this section of the motel they wanted to make seasonal and not run the boiler for a couple of rooms in the late fall or early spring. I installed electric heaters in the 8 rooms and put a sp-dt switch off of the ac circuit so they couldn't run both but could switch from ac to heat. Same circuit.

 

[iwire]

Would you agree that my example of my connection of a 120 volt air handler to the circuit that supplies 120 volt control power to a steam boiler an example that would be covered under exception #2?

Not really sure to tell you the truth.

I sure don't see a safety hazard in doing it.

 

[don_resqcapt19]

Bob,

In my opinion when they say

Permanently connected air-conditioning equipment shall be permitted to be connected to the same branch circuit.

They are not taking about an air conditioning compressor.

IMO they are taking about any equipment that conditions the air.

Humidifiers, De-Humidifiers, electronic air cleaners etc.

Then why do we have exception #1?

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.

It is my opinion that exception #2 permits the air conditioning (cooling) equipment to be connected to the same branch circuit that serves the central heating equipment on the assumption that these two loads are mutually exclusive. However in many cases the rating of the central heating branch circuit would not be suitable to supply the air conditioning equipment.
Don

 

[iwire]

Bob,
Then why do we have exception #1?[/FONT]

I admited I was mistaken and Marc was correct about exception 1. :smile:

 

[LarryFine]

. . . it should be worded better if that is thier intention.

Gee, that's never happened before. :roll:

 

[Pierre C Belarge]

I believe that Don is correct, and this exception deals with NonCoincendental loads as per 220.60