indoor unit disconnect
- Thread starter Ponchik
- Start date
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- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
Are you asking about a mini split or a standard heat pump system. If the latter then I believe you need a disconnect. Mant systems have heat strips in them for backup heat but that depends where you are from.
422.31(C) applies. How about the disconnect not within sight but it is lockable? The way that I read the 440.14 it will not allow lockable disconnect. Am I correct in reading that correctly?
No heating strip.
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
If it doesn't have a hermetic compressor it isn't covered by 440, it tells us this in 440.1
Air handler only is covered in art 422. Somewhere in there it tells us the branch circuit device can be the disconnecting means if no more then 300VA or 1/8 hp. Over those values typically requires a disconnect within site of the unit.
If it has electric heat we need to go to 424.
wwhitney
Senior Member
- Location
- Berkeley, CA
- Occupation
- Retired
What about 430.112, which covers a single disconnecting means "where a number of motors drive several parts of a single machine"?
Cheers, Wayne
Cheers, Wayne
But I can not look at the air conditioner or the indoor fan as a motor only even though it is mostly a motor load. I see it as an appliance 422 or an A/C unit 440.
Yes over those values does require a local disconnect 422.31(C) for an appliance (air conditioner is considered an appliance) but at the same time it does allow a lockable disconnect. However, the 440.14 does not allow a lockable off site disconnect.
So it seems to me that 440 contradicts with 422.
wwhitney
Senior Member
- Location
- Berkeley, CA
- Occupation
- Retired
How about 440.8? It says "An air-conditioning or refrigerating system shall be considered to be a single machine under the provisions of 430.87, Exception, and 430.112, Exception.
The motors shall be permitted to be located remotely from each other."
Cheers, Wayne
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
I think that would only apply to a situation where multiple motors (or even other loads within that machine) are all disconnected by the same branch circuit device. A typical "mini split" may fit in this description, but the typical central air unit is two separate units supplied by two separate branch circuits, though they do work together as one system.
electrofelon
Senior Member
- Location
- Cherry Valley NY, Seattle, WA
:thumbsup: thanks
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
IMO, the air handler is a motor and falls under 430. I have never seen an air handler on a ducted system that did not require a disconnect. No way is the motor is not more than 1/8 hp.
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
It is really no different than a gas furnace so either way 422, 424 or 430 will still require a disconnect
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
Traditional North American marketed air handlers you likely won't find with that small of a motor.
I did connect a VRF system in a school building a couple years ago, most the air handlers were not "ducted units" but there were a couple that were. They were less then 300 VA rated. There were some higher volume air handlers used on that system also - those did draw enough we needed to add a disconnect.
I disagree that it is a motor - it is a motor operated appliance. 422 can send you to 430 for certain things though.
But you can work on the indoor unit as a separate appliance and it is an independent unit than the condenser.
The indoor unit of a heat pump will turn off when the outdoor unit's disconnect is turned off. One can not service/troubleshoot the indoor unit without the outdoor power being on. So it is part of an outdoor unit. Also, 422 allows the disconnect to be off site as long as it is lockable in the off position.
So if 422 allows the off site lockable disconnect (even for more than 1/8 HP ) does 440 have the authority to overrule it?
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
Almost always the other way, especially traditional North American marketed units. Indoor unit sends a control signal to the outdoor unit to tell it to run.
What did I say that contradicts your statement?
I don't think 440 would trump it as no compressor is involved . Since a motor (controller) is involved 430.102 would require an in-sight. IMO, starting with the change in '11, 422.31(C) clarifies a in-sight disconnect is required.
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
You said "The indoor unit of a heat pump will turn off when the outdoor unit's disconnect is turned off." Not true for the majority of the units. You will still have indoor unit running and will still have 24 volts to the contactor coil of the outdoor unit because the control power comes from the indoor unit. The compressor will stop and you won't get any heat/cooling from the refrigerant but the indoor blower and any back up heat still function.
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