Split A/C Systems and Local Disconnect Requirements

[coffeebean]

I read the manufacturers installation instructions 110.3(B) if it requires it,then you will install a disconnect for the indoor unit.
If there is no requirement then no disconnect is required, pretty simple.

 

[jaggedben]

I read the manufacturers installation instructions 110.3(B) if it requires it,then you will install a disconnect for the indoor unit.
If there is no requirement then no disconnect is required, pretty simple.

Not really. If the manufacturers instructions say to not install a disconnect, or something to that effect (e.g. only use the cable we supply without cutting it) then you wouldn't install a disco. But if the instructions say nothing one way or the other then NEC requirements come into play. Also manufacturers do pay attention to NEC requirements, at least to some degree, so that reduces the likelihood that instructions would contradict NEC requirements. Instructions are more likely to say 'follow applicable local code requirements.'

 

[mtnelect]

I install "Daikin" ductless systems, which use "Inverter Technology" and the connecting cables between the outside and inside units use high frequency communication channels that develop harmonics that will disturb GFCI's. Also, you must make sure that those cables are not close to line voltage for possible interference when they leave the unit.


As more "Digital/Electronics" are used in our appliances and equipment we have to be careful on how we wire them.

 

[ActionDave]

...... Also, you must make sure that those cables are not close to line voltage for possible interference when they leave the unit.


As more "Digital/Electronics" are used in our appliances and equipment we have to be careful on how we wire them.

Can you just wrap them in aluminium foil?

 

[winnie]

The Ductless or Mini Splits are all direct current.

I can confirm that this is not correct for the systems in my house.

These are fairly modern Fujitsu 'DC Inverter' units. The power supplied from the outdoor unit to the indoor is line voltage AC.

In both the indoor and outdoor units there are rectifier and inverter systems for the various motors.

-Jon

 

[mtnelect]

I can confirm that this is not correct for the systems in my house.

These are fairly modern Fujitsu 'DC Inverter' units. The power supplied from the outdoor unit to the indoor is line voltage AC.

In both the indoor and outdoor units there are rectifier and inverter systems for the various motors.

-Jon

Split A/C Systems and Local Disconnect Requirements - Go to Post No. 17​

I only install "Daikin" which is direct current, did not know that line voltage ductless mini splits every existed.

 

[tom baker]

I read the manufacturers installation instructions 110.3(B) if it requires it,then you will install a disconnect for the indoor unit.
If there is no requirement then no disconnect is required, pretty simple.

And in some areas that will get you a correction notice. As pointed out the enforcement is spotty. The mfgs instructions and the NEC requirements do not always alighn.

 

[electrofelon]

Ooo ooo, opportunity for a mini rant and to bash the NEC here! These ductless systems have been around for how long now and are becoming more and more popular everyday. Clearly the indoor disconnect thing is vague and causes constant consternation in the field. Maybe the code writers could say what they want here instead of spending time on ridiculous things like this new 1/4 conductor fill allowance for EGC's? Just an idea.

 

[mtnelect]

In this "Digital/Electronic" age things are getting a little "Foggy" ... The "Old School Wiring" is having a problem dealing with it.

 

[mtnelect]

It looks like some of the Electricians are going to have to take some courses on Electronics !

 

[mtnelect]

Can you just wrap them in aluminium foil?

I think not ! ...

 

[mtnelect]

And in some areas that will get you a correction notice. As pointed out the enforcement is spotty. The mfgs instructions and the NEC requirements do not always alighn.

In Europe they figured it out long ago before us.

 

[kwired]

Ooo ooo, opportunity for a mini rant and to bash the NEC here! These ductless systems have been around for how long now and are becoming more and more popular everyday. Clearly the indoor disconnect thing is vague and causes constant consternation in the field. Maybe the code writers could say what they want here instead of spending time on ridiculous things like this new 1/4 conductor fill allowance for EGC's? Just an idea.

I'm with you here. These been around quite a while and you still can't get a consensus on what is or isn't allowed with certain aspects, then the HVAC guys say the warranty is void if you don't use the cable they provide to go between units, which typically seems to be a tray cable type, but nothing too special about it that you would think would impact performance. Most them I have installed I only run power to outdoor unit and HVAC installer runs interconnect line to indoor unit(s). Have not had a lot of them that were inspected, but haven't had any problems passing on the few that were inspected either.

 

[Carsongville]

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.

Would you happen to have that verbiage? We are looking for some language to create our own exemption. Thanks!

 

[tortuga]

Would you happen to have that verbiage? We are looking for some language to create our own exemption. Thanks!

You don't need an exemption 422.31 covers it.

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.

That is how Oregon interprets it, the indoor unit is an appliance.

https://www.oregon.gov/bcd/codes-stand/Documents/interp-09-01-el-hvac-disconnect.pdf

the HVAC guys say the warranty is void if you don't use the cable they provide to go between units, which typically seems to be a tray cable type,

They were insisting I use that tray cable, was told that's becasue tray cable is rated 75C and UF is rated 60C. Not sure why that matters.

 

[suemarkp]

Would you happen to have that verbiage? We are looking for some language to create our own exemption. Thanks!

440.014 Disconnecting means.
In one- and two-family dwelling units, a disconnecting means is required for the indoor units(s) of a split system HVAC/R system, unless the outside unit's disconnecting means is lockable, disconnects the indoor unit(s), identifies the location of all indoor units, and an indoor disconnecting means is not required by the manufacturer.