# Help with wiring for Mini split



## P-Electrician (Aug 2, 2012)

I am wiring a ductless mini split tomorrow and was not sure what to run between the outdoor unit and the indoor unit. Manual says 14 gauge wire but says nothing about method. I've seen them done with SJ, and SOOW so I got a cut of 12-4 SOOW. What would you guys use?


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## erics37 (May 7, 2009)

P-Electrician said:


> I am wiring a ductless mini split tomorrow and was not sure what to run between the outdoor unit and the indoor unit. Manual says 14 gauge wire but says nothing about method. I've seen them done with SJ, and SOOW so I got a cut of 12-4 SOOW. What would you guys use?


Usually it needs to be solid conductors, unspliced if possible. I've run 14-3 UF cable out there, then into a 3-pole disconnect switch near the indoor unit and regular romex from there. Maybe once or twice I've run a straight-through unspliced piece of romex between the units :whistling2:

On commercial installations you usually can't get away with romex, gotta get a bit more spendy.

You can't use article 400 wiring methods for permanent installations, especially if you're burying them in a wall.


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## McClary’s Electrical (Feb 21, 2009)

I was going to reply but it would have been word for word what Eric posted. I would only add that if you're not sure what unit they are using and you have to rough in, I would recommend two 14/3's for communication and a 12/2 for power. 

Hey Eric, System of a down and Deftones Tuesday night. My two favorite bands:thumbsup:


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## erics37 (May 7, 2009)

mcclary's electrical said:


> I was going to reply but it would have been word for word what Eric posted. I would only add that if you're not sure what unit they are using and you have to rough in, I would recommend two 14/3's for communication and a 12/2 for power.
> 
> Hey Eric, System of a down and Deftones Tuesday night. My two favorite bands:thumbsup:


I like Deftones a lot, but System of a Down can lick my fartbox.


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## P-Electrician (Aug 2, 2012)

Just found it 400.8. UF sounds like a much better idea, I'll pick up some 14/3 on the way to the job. The SOOW just sounded really hack to me, is it ok to tie-wrap it to the insulated lines inside the lineset?


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## cc2kj (Aug 3, 2012)

I just did a Fujitsu mini split with 1 outdoor unit and 2 indoor units. Outdoor unit was 220VAC and I ran 2 #12 and ground on a 2 pole 20 amp breaker to it. The voltage to feed the 2 indoor units was DC voltage fed from the outdoor unit. Each one was a individual line from the outdoor unit. I ran 14/3 UF along with the line set to each indoor unit. I don't think the 3 pole disconnect at the indoor unit is required, just the outdoor unit.


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## erics37 (May 7, 2009)

P-Electrician said:


> Just found it 400.8. UF sounds like a much better idea, I'll pick up some 14/3 on the way to the job. The SOOW just sounded really hack to me, is it ok to tie-wrap it to the insulated lines inside the lineset?


What kind of building is it?

Around here they usually just run their lineset exposed, and then put some sort of nonmetallic trough cover thing over it. I usually run my wires inside of that with their lineset and then split off near the unit and go to my disconnect. That way the HVAC guys have to do all the drilling and cutting :thumbup:


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## P-Electrician (Aug 2, 2012)

The unit is in place and its a fujitsu (Spelling is questionable) Recomended branch circuit is 30amp so i am feeding it with a 2 pole 30, 10-2 nm to a j box, changeover to 3/4" PVC, LB out and pipe to the Pullout disconnect. Metallic liquidtight from there to the unit. control wiring they said use #14 conductors


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## erics37 (May 7, 2009)

cc2kj said:


> I don't think the 3 pole disconnect at the indoor unit is required, just the outdoor unit.


Usually equipment needs a disconnecting means within sight, even when it's part of a bigger system. That being said, I've "neglected" to install a lot of disconnects at the indoor units.


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## erics37 (May 7, 2009)

P-Electrician said:


> The unit is in place and its a fujitsu (Spelling is questionable) Recomended branch circuit is 30amp so i am feeding it with a 2 pole 30, 10-2 nm to a j box, changeover to 3/4" PVC, LB out and pipe to the Pullout disconnect. Metallic liquidtight from there to the unit. control wiring they said use #14 conductors


Sometimes it will say use #16 unless it's over a certain distance; I always just use #14 anyway. But definitely use solid conductors! I used stranded once and it didn't work until I replaced them with solid wires :blink:


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## P-Electrician (Aug 2, 2012)

erics37 said:


> What kind of building is it?
> 
> Around here they usually just run their lineset exposed, and then put some sort of nonmetallic trough cover thing over it. I usually run my wires inside of that with their lineset and then split off near the unit and go to my disconnect. That way the HVAC guys have to do all the drilling and cutting :thumbup:


Single family dwelling, it is going to have the nonmetallic covering too. The HVAC guy already drilled the hole so plus for me :thumbsup:.


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## erics37 (May 7, 2009)

P-Electrician said:


> Single family dwelling, it is going to have the nonmetallic covering too. The HVAC guy already drilled the hole so plus for me :thumbsup:.


Sounds like you're set. Normal 30 amp circuit to the outdoor unit, run a 14-3 UF cable back to the indoor unit.


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## cc2kj (Aug 3, 2012)

And when I say outdoor unit, I mean only a disconnect for the 220VAC line.


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## P-Electrician (Aug 2, 2012)

erics37 said:


> Usually equipment needs a disconnecting means within sight, even when it's part of a bigger system. That being said, I've "neglected" to install a lot of disconnects at the indoor units.


Manual says field supplied disco switch for indoor unit but its not getting it on this install, The pullout next to the outdoor unit kills the whole thing anyway so i don't see the need.


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## nolabama (Oct 3, 2007)

mcclary's electrical said:


> Hey Eric, System of a down and Deftones Tuesday night. My two favorite bands:thumbsup:


where?


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## Dfresh64 (Sep 10, 2011)

The ones that I've done the hvac guy run the 6 conductor cable .... It has 2 -14 , then 4 -18. 
I run 30 amp to dis then to unit , then hvac runs cable to indoor unit fr the cond unit ...The 14 gage is low voltage BUT their are different types of units Good luck


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## McClary’s Electrical (Feb 21, 2009)

erics37 said:


> I like Deftones a lot, but System of a Down can lick my fartbox.


I should have added that system was my favorite band in the late 90's . Deftones ever since:rockon:


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## McClary’s Electrical (Feb 21, 2009)

nolabama said:


> where?


 
In DC, Brian Johns back yard:thumbsup:


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## McClary’s Electrical (Feb 21, 2009)

Dfresh64 said:


> The ones that I've done the hvac guy run the 6 conductor cable .... It has 2 -14 , then 4 -18.
> I run 30 amp to dis then to unit , then hvac runs cable to indoor unit fr the cond unit ...The 14 gage is low voltage BUT their are different types of units Good luck


 
That's cool. I've never seen one that could use 18 guage. The one's I've done are proteced at 15 amps and they're 120 volt controls, not LV


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## cc2kj (Aug 3, 2012)

mcclary's electrical said:


> That's cool. I've never seen one that could use 18 guage. The one's I've done are proteced at 15 amps and they're 120 volt controls, not LV


I think each manufacturer has their own way of doing it. I know Daiken has an entirely different way of doing it.


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## McClary’s Electrical (Feb 21, 2009)

cc2kj said:


> I know Daiken has an entirely different way of doing it.


 
Holy smokes never even seen one of those


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## Shockdoc (Mar 4, 2010)

mcclary's electrical said:


> That's cool. I've never seen one that could use 18 guage. The one's I've done are proteced at 15 amps and they're 120 volt controls, not LV


There are some that just require an 18/2 between units , both independently fed.


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## Shockdoc (Mar 4, 2010)

14/3 romex, but NEC enforcement where you live might enforce you to spice to thwn at the exit point of your interior wall. 12/5 CT cable- good for 4 wire system, thwn conductors.


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## Dfresh64 (Sep 10, 2011)

Ive Hook 2 types LG & Mitsubishi both types were very easy to hook up .


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## McClary’s Electrical (Feb 21, 2009)

cc2kj said:


> I don't think the 3 pole disconnect at the indoor unit is required, just the outdoor unit.


 

*(B) Appliances Rated over 300 Volt-Amperes or​​​​1⁄8​
Horsepower.​*​​​​For permanently connected appliances rated
over 300 volt-amperes or 1⁄8 hp, the branch-circuit switch or
circuit breaker shall be permitted to serve as the disconnecting
means where the switch or circuit breaker is within
sight from the appliance or is capable of being locked in the
open position. The provision for locking or adding a lock to
the disconnecting means shall be installed on or at the
switch or circuit breaker used as the disconnecting means​
and shall remain in place with or without the lock installed.


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## Shockdoc (Mar 4, 2010)

mcclary's electrical said:


> *(B) Appliances Rated over 300 Volt-Amperes or​1⁄8​
> Horsepower.​*For permanently connected appliances rated
> over 300 volt-amperes or 1⁄8 hp, the branch-circuit switch or
> circuit breaker shall be permitted to serve as the disconnecting
> ...


A regular 60 amp pullout can be locked and cannot be energized if the worker holds on to the insert. I wouldn't waste my money on a 3 pole disco.


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## wendon (Sep 27, 2010)

Usually the HVAC guy runs the cable between the outdoor unit and the indoor unit. I think they are low voltage on the indoor unit.


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## cc2kj (Aug 3, 2012)

mcclary's electrical said:


> *(B) Appliances Rated over 300 Volt-Amperes or​1⁄8​*
> 
> *Horsepower.
> *For permanently connected appliances rated
> ...





Has anyone seen a nice looking disconnect that a customer wouldn't mind seeing in their living room?​


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## backstay (Feb 3, 2011)

cc2kj said:


> has anyone seen a nice looking disconnect that a customer wouldn't mind seeing in their living room?


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## McClary’s Electrical (Feb 21, 2009)

cc2kj said:


> Has anyone seen a nice looking disconnect that a customer wouldn't mind seeing in their living room?


A switch


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## MechanicalDVR (Dec 29, 2007)

Every one of these threads about mini splits comes down to the same arguement about if the indoor unit needs a disconnect or not. If the cost of a multi pole switch and a 4"x4" box and cover is going to throw your job over cost I think you really need to evaluate your pricing/bidding structure.


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## Shockdoc (Mar 4, 2010)

We don't use switches for the inside 1/2 in these parts.


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## randomkiller (Sep 28, 2007)

Shockdoc said:


> We don't use switches for the inside 1/2 in these parts.


 
From what I see you are in the same area as I am and 95% of the time we use swtches on the indoor units. Unless they have back up rack heat installed the amperages are relatively very low.


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## Jottinger2015 (Mar 22, 2021)

P-Electrician said:


> I am wiring a ductless mini split tomorrow and was not sure what to run between the outdoor unit and the indoor unit. Manual says 14 gauge wire but says nothing about method. I've seen them done with SJ, and SOOW so I got a cut of 12-4 SOOW. What would you guys use?


I ran one with 12- 2 wire 20 am disconnect outside by the compressor outside units


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## MechanicalDVR (Dec 29, 2007)

Jottinger2015 said:


> I ran one with 12- 2 wire 20 am disconnect outside by the compressor outside units


WOW! Talk about bringing back a dead thread....2012!

Normally they require three conductors between the indoor and outdoor unit.


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## kb1jb1 (Nov 11, 2017)

I also got caught up in an old thread. As I am reading the comments here I am saying to myself, don't these people know about mini split cable that is rated for the indoor unit. Then I noticed the dates of the comments. Mini split cable was not around back then.


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## Dennis Alwon (May 9, 2009)

I wish these new members would look at the date of these threads. It seems like there have been a bunch of walking dead around here lately.


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