Disco, Mitsubishi mini splits.

iwire

Moderator
Staff member
Location
Massachusetts
I understand the reasoning for the disconnect and I'm in agreement with you. I think a problem starts to arise (in a residential situation anyway) when you have to install an ugly looking disconnect next to a very neat looking AHU. It's one thing to locate a disconnect in an attic or a closet but quite another to put a big ugly switch on a wall in someone's dining room.
If you use the switch I show in post 2 all you see is a brown bat handle with any single gang switch plate you would like. I am not suggesting mounting a NEMA1 fused safety switch on the living room wall.

Beyond that ... well not my problem if they customer does not like the code and or manufacturer required parts.
 

kwired

Electron manager
Location
NE Nebraska
This indoor unit is also meets the definition of an appliance. I see no reason why the manufacturers can't put a unit switch on it for disconnecting means. If the unit is rated less then 300 VA or 1/8 hp, 422.31 allows the branch circuit device to be the disconnecting means.

Most of these units probably are 1/8 hp or less.
 

iwire

Moderator
Staff member
Location
Massachusetts
This indoor unit is also meets the definition of an appliance.
We do not get to pick though, we have to go by the listing which I imagine is 'air conditioning equipment' or some such thing.

I see no reason why the manufacturers can't put a unit switch on it for disconnecting means.
I agree they could, but they don't. I suspect that maybe only NEC areas of the world require this disconnect for such a low powered motor.

Most are lucky to have any unit mounted controls at all, most if not all I have done are strictly remote controlled.
 

kwired

Electron manager
Location
NE Nebraska
We do not get to pick though, we have to go by the listing which I imagine is 'air conditioning equipment' or some such thing.



I agree they could, but they don't. I suspect that maybe only NEC areas of the world require this disconnect for such a low powered motor.

Most are lucky to have any unit mounted controls at all, most if not all I have done are strictly remote controlled.
How is it any different then a larger air handler and compressor unit? Art 440 applies to the unit containing the compressor - if the air handler doesn't also contain a compressor it is a 422 appliance when it comes to which NEC articles apply. It still may be listed as air conditioning equipment, and most are.

One thing that my be different is listing of the entire system. The typical central units are more interchangeable with other compressor units, where these mini split systems may be more matched to work with a specific compressor unit?
 

kwired

Electron manager
Location
NE Nebraska
After reading 440.1, if it is supplied from same branch circuit as the outside unit - it is probably covered by 440.

For your typical central unit with separate branch circuits to indoor and outdoor units - the indoor unit is a 422 application the outdoor unit is a 440 application.
 

iwire

Moderator
Staff member
Location
Massachusetts
After reading 440.1, if it is supplied from same branch circuit as the outside unit - it is probably covered by 440.

For your typical central unit with separate branch circuits to indoor and outdoor units - the indoor unit is a 422 application the outdoor unit is a 440 application.
OK lets say it an appliance, what have we gained?

Nothing but a lot of typing because it still needs a disconnecting means. :D
 

romex jockey

Senior Member
Location
Vermont
Wouldn't 430.102 B ex apply if these mini's were manufactured loto capable?

Exception to (1) and (2): The disconnecting means for the
motor shall not be required under either condition (a) or
condition (b), which follow, provided that the controller
disconnecting means required in 430.102(A) is lockable in
accordance with 110.25
~RJ~
 

romex jockey

Senior Member
Location
Vermont
Kwired....

Am i reading the ex wrong?

It reads (to me) if said inside controller unit's 'on/off switch' met 110.25 430.109&110, nothing else would be required

~RJ~
 
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Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Electrical Contractor
Kwired....

Am i reading the ex wrong?

It reads (to me) if said inside controller unit's 'on/off switch' met 110.25, nothing else would be required

~RJ~
That is true but it has to disconnect everything. Most of these units have remotes so I doubt the on/off would disconnect all the power
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Electrical Contractor
Wouldn't locking out the controller essentially disconnect the remote motor?

~RJ~
I am talking about a remote control... If the switch on the unit-- which I don't believe I have seen any since the units are generally mounted high on the wall- disconnected everything then the remote control would not work
 

romex jockey

Senior Member
Location
Vermont
Hand held remote then?....

ok, i get it Denny.


Keep in mind the mini-splits are still a highly competitive unsaturated market , so if one provided a cheaper install it essentially wins said market. Even our poco's and state subsidized energy efficiency folks foist them as 'green' (a might pale shade imo...)

To be truthful i don't see much in the way of motorized appliances loto capable, where they so one could apply the letter of the code (ex's do count,albeit often overlooked)

Just keep 'em under 6'7"& compliant .....everyone wins.....

~RJ~
 

kwired

Electron manager
Location
NE Nebraska
Wouldn't 430.102 B ex apply if these mini's were manufactured loto capable?



~RJ~

If the units had LOTO provisions on them there wouldn't be any problem.

There is two disconnect requirements in 430.102, one if for the motor, one for the motor controller. When motor and controller are within sight of one another a single disconnect can cover both - this is what you would have with this air handler as the motor controller is within the unit.

The on off switches on these units is typically only a part of the controls and not a disconnecting means that manually opens the power circuit.

If it has wireless remote control as mentioned that certainly is capable of turning the unit on, but it is just an extension of the control circuit not part of a disconnect.
 

iwire

Moderator
Staff member
Location
Massachusetts
Wouldn't 430.102 B ex apply if these mini's were manufactured loto capable?
Exception to (1) and (2): The disconnecting means for the
motor shall not be required under either condition (a) or
condition (b)
, which follow, provided that the controller
disconnecting means required in 430.102(A) is lockable in
accordance with 110.25
Which condition specified above, (a) or (b) would apply to a typical dwelling unit, wall mounted air handler?
 
Every Nema 3R disconnect I have installed for the outdoor unit of a minisplit had a padlock hole, so when locked, the indoor unit has NO power going to it. Isn't that what LOTO means?

So those still arguing appliance terminology does not alter need for a disconnect, what do you use for disposals, dishwashers and ovens?
 

augie47

Moderator
Staff member
Location
Tennessee
Every Nema 3R disconnect I have installed for the outdoor unit of a minisplit had a padlock hole, so when locked, the indoor unit has NO power going to it. Isn't that what LOTO means?
The 430.102 Section on motor disconnects has an exception where a LOTO program is in effect for industrial installations. There is, to my knowledge, any such exemption for commercial/residential.
So those still arguing appliance terminology does not alter need for a disconnect, what do you use for disposals, dishwashers and ovens?
Some are cord and plug connected, some have a unit switch with an off position which disconnects the actual line power and the branch circuit device can often serve as the other disconnecting means (details are in 422.34),and in some cases a breaker lock may be required.
 
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