Split A/C Systems and Local Disconnect Requirements

[jbt260]

When the indoor unit of a split-system A/C unit gets power from the outdoor condensing unit, does the indoor unit require a local disconnect switch if the outdoor unit has a lockable disconnect switch?

 

[mtnelect]

When the indoor unit of a split-system A/C unit gets power from the outdoor condensing unit, does the indoor unit require a local disconnect switch if the outdoor unit has a lockable disconnect switch?

Looks like you're talking about a "Ductless" system, which the inside air handler receives its power from the outside condensing unit. The outside unit gets it power directly from a breaker or disconnect. The whole system is direct current generated from the outside unit's power supply. No disconnect is needed for the inside air handler.

 

[tom baker]

In WA we have an exemption for inside disconnect for one and two family dwelling units, meaning a disconnect is required for any other occupancy.

 

[tom baker]

Suggest you read thru the rules in 430.102

 

[mtnelect]

Suggest you read thru the rules in 430.102

The Ductless or Mini Splits are all direct current.

 

[jaggedben]

Looks like you're talking about a "Ductless" system, which the inside air handler receives its power from the outside condensing unit. ...

It doesn't seem to me that the question is specific to ductless systems. I have a ducted system where the air-handler gets its power from the outside condensing unit.

The Ductless or Mini Splits are all direct current.

That doesn't make a difference to whether 430.102 applies.

 

[mtnelect]

It doesn't seem to me that the question is specific to ductless systems. I have a ducted system where the air-handler gets its power from the outside condensing unit.

That doesn't make a difference to whether 430.102 applies.

I only install "Daikin" and the inside fan unit has an on/off button, does that meet NEC 430.102 ? None of their installation manuals require a field installed disconnect.

 

[jbt260]

This particular installation is ductless.

 

[jaggedben]

I only install "Daikin" and the inside fan unit has an on/off button, does that meet NEC 430.102 ?

Can't tell from here. There are quite a few options in 430.109.

 

[mtnelect]

It doesn't seem to me that the question is specific to ductless systems. I have a ducted system where the air-handler gets its power from the outside condensing unit.

That doesn't make a difference to whether 430.102 applies.

May I ask, what brand and model number are your ducted system, which provide the inside are-handler power from the outside condensing unit ?

 

[augie47]

From my experience, the requirement for a disconnect is not addressed universally in every jurisdiction. As noted, most inspectors apply 430.102 and often do not require a local disconnect per 430.109(B)

 

[jaggedben]

May I ask, what brand and model number are your ducted system, which provide the inside are-handler power from the outside condensing unit ?

Fujitsu

 

[mtnelect]

Fujitsu

The only systems I could find that get power from the outside condensing unit are ductless systems which are all dc. The inside ducted air- handlers are all 220 AC which requires a disconnect. I have never seen an inside ducted air-handler powered from an outside condensing unit.

 

[wwhitney]

The only systems I could find that get power from the outside condensing unit are ductless systems which are all dc.

DC or AC doesn't matter for this topic.

I also have a Fujitsu indoor air handler powered only by the outdoor unit. [I installed a double pole snap switch as a disconnect.] It's one of their Slim Duct low static pressure units, similar to this one, although my model number is different:

Slim Duct - AIRSTAGE SINGLE-ROOM MINI-SPLIT SYSTEMS - Residential - FUJITSU GENERAL United States & Canada

Slim Duct - AIRSTAGE SINGLE-ROOM MINI-SPLIT SYSTEMS - Residential - FUJITSU GENERAL United States & Canada

www.fujitsugeneral.com

Cheers, Wayne

 

[mtnelect]

DC or AC doesn't matter for this topic.

I also have a Fujitsu indoor air handler powered only by the outdoor unit. [I installed a double pole snap switch as a disconnect.] It's one of their Slim Duct low static pressure units, similar to this one, although my model number is different:

Slim Duct - AIRSTAGE SINGLE-ROOM MINI-SPLIT SYSTEMS - Residential - FUJITSU GENERAL United States & Canada

Slim Duct - AIRSTAGE SINGLE-ROOM MINI-SPLIT SYSTEMS - Residential - FUJITSU GENERAL United States & Canada

www.fujitsugeneral.com

Cheers, Wayne

Yes, "Daikin" has that option to, but they are all "Ductless" systems powered by cable from the outside condensing unit's dc power supply.

 

[jaggedben]

The only systems I could find that get power from the outside condensing unit are ductless systems which are all dc. The inside ducted air- handlers are all 220 AC which requires a disconnect. I have never seen an inside ducted air-handler powered from an outside condensing unit.

How are you saying ducted air handlers are normally powered?

I'm not sure what the misunderstanding is here but the vast majority of home HVAC systems I've seen have the air-handler powered via the outside unit. The exceptions seem to be when the air-handler also does something besides just blowing air, like it handles a furnace input, or has an auxiliary resistance heating strip, or maybe sometimes when there's HEPA filtering. In those cases the air handler usually has its own circuit and breaker back to the panel.

FWIW my air handler has a snap switch disconnect similar to what Wayne described.

 

[mtnelect]

I apologize, found the installation manual you were talking about. I never knew this model existed for line voltage operation, learn something every day.

 

[tom baker]

From my experience, the requirement for a disconnect is not addressed universally in every jurisdiction. As noted, most inspectors apply 430.102 and often do not require a local disconnect per 430.109(B)

Agree with your observation. Washington’s AHJs do a good of of understanding the NEC, and adopting reasonable rules where the NEC is not clear

 

[kwired]

IMO this is a motor operated appliance and 422.31 should apply. These are usually less than 300VA or 1/8 HP so lockable branch circuit device is the most that is required if it is not within sight.

They don't contain a hermetic refrigerant compressor so 440 does not apply. The outdoor unit does have the compressor so 440 applies to the outdoor unit.

 

[jaggedben]

IMO this is a motor operated appliance and 422.31 should apply. ...

I my opinion the definition of appliance is too general to determine whether a disconnecting means at the outdoor unit satisfies 422.31 for the whole system. Are the indoor and outdoor units 'installed or connected as a unit'? I.e. are they one appliance or two? In other words, 422 doesn't seem to have a clear answer to the original question, which was whether the indoor unit needs its own separate disco when powered from the outdoor unit.