wire for a split HVAC system

[Stevenfyeager]

A customer is buying a small "split" HVAC for a new room addition. The kit comes with a 4-wire, (14-3 with ground) cord to go between the inside and outside units. The system is rated 15 amps, 208/240 V. Do I need to run a 4 wire supply to the outside unit, or is a 3 wire supply ok? Does the system need a neutral supply instead of just a 3 wire? I've called the company and the tech wasn't much help. Thank you

 

[Dennis Alwon]

I don't know why it comes with a cord because imo it is not compliant to run the cord thru the walls based on 400.7 & 8.

We usually feed the disconnect to the outside unit and run a 14/3 nm to the inside unit. I don't believe I have ever seen one that takes a 14/4--they do make 14/4nm. I have seen a mini split that was 120v but usually they are 240v.

 

[goldstar]

I don't know why it comes with a cord because imo it is not compliant to run the cord thru the walls based on 400.7 & 8.

We usually feed the disconnect to the outside unit and run a 14/3 nm to the inside unit. I don't believe I have ever seen one that takes a 14/4--they do make 14/4nm. I have seen a mini split that was 120v but usually they are 240v.

What if the unit was passed through UL with the cord ? From what I am told some mfrs. are making cords that are listed for use through the wall. Also, read the mfr's instructions. You may have to install a disconnect switch at the inside unit. This is a wiring diagram for a Mitsubishi split unit model:

http://www.rectorseal.com/ss610e-wiring/MITSUBISHI_610E-wiring2.pdf

 

[augie47]

I would be surprised if it were UL listed using a cord. Things change continually but at one time the only units that showed or provided a cord for interconnect were CSA listed (apparently such installs are permitted under Canadian Code)
As a side note, at one time the same manufacturers directions that allowed the cord called for the refrigerations lines and cord be wrapped in a vinyl wrap.
The mini-splits installs have presented interesting challenges for a number or years partially due to the misleading info on use of cords and TC cables for installations.
Most jurisdictions will not accept the cord installs based on various sections of 400.7 & 400.8
There have been a fair number of discussions on the Forum about the installs which you can find with a search

(Here's one interesting thread on the switch requirement: http://forums.mikeholt.com/showthread.php?t=173351&highlight=mini-split )