# Mini spit wiring



## WronGun (Oct 18, 2013)

This is my first minisplit unit I’m Wiring.

Currently , I have 6 insulated conductors and 2 grounds going out to the unit and to the inside... 

It seems I need a communication wire also with shield... does anyone have experience with this that could shed some light










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## macmikeman (Jan 23, 2007)

What brand of mini split . Sometimes a teeny bit of information is helpful. Just a teeny bit wrongun


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## Dennis Alwon (May 9, 2009)

All you need is a 14/2 power cable to the outdoor unit and a 14/3 between the outdoor unit and the indoor unit. The red wire of the 14/3 is the communication wire.

The 14/3 should have the shielded conductor because it is from the factory.

In the past we used 14/3 nm and never had an issue-- not sure what this new cable is


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## HackWork (Oct 2, 2009)

Remember the disconnect for the inside unit.


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## HackWork (Oct 2, 2009)

Those instructions are convoluted the way they list the Communication Wiring at the end making it seem that it's additional.


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## MechanicalDVR (Dec 29, 2007)

Dennis Alwon said:


> All you need is a 14/2 power cable to the outdoor unit and a 14/3 between the outdoor unit and the indoor unit. The red wire of the 14/3 is the communication wire.
> 
> The 14/3 should have the shielded conductor because it is from the factory.
> 
> In the past *we used 14/3 nm* and never had an issue-- not sure what this new cable is


Gee I'm surprised using nm in a wet location!


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## frenchelectrican (Mar 15, 2007)

Wrongun .,

what brand the mini split unit it is?


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## nrp3 (Jan 24, 2009)

UF takes care of the wet location. But not the shielding.


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## splatz (May 23, 2015)

dcne.com


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## manchestersparky (Mar 25, 2007)

HackWork said:


> Remember the disconnect for the inside unit.


I see this missed more often then not !
I've even mentioned it to the EC on site when doing another inspection for them , and they still don't install one.


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## Going_Commando (Oct 1, 2011)

manchestersparky said:


> I see this missed more often then not !
> I've even mentioned it to the EC on site when doing another inspection for them , and they still don't install one.


They don't because it is stupid and unnecessary.


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## HackWork (Oct 2, 2009)

Going_Commando said:


> They don't because it is stupid and unnecessary.


I agree, but it is a code requirement and a pain in the ass to go back and install if you fail an inspection for it..


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## WronGun (Oct 18, 2013)

HackWork said:


> Those instructions are convoluted the way they list the Communication Wiring at the end making it seem that it's additional.




Exactly ! I thought I was losing my head. It’s a carrier unit. 

I ran 14/3 to the outside unit from the panel 

I ran another 14/3 from the outside unit to the inside unit...

Nothing is hooked up yet , we just did the rough install.

The only thing that’s not in my pipe is this 16 awg shielded wire 

The directions for this unit are horrible as far as wiring is concerned 

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## Going_Commando (Oct 1, 2011)

HackWork said:


> I agree, but it is a code requirement and a pain in the ass to go back and install if you fail an inspection for it..


I've never put one in, and never failed inspection for it. if you have a pull-out disconnect outside, and padlock the cover shut, doesn't that provide a disconnecting means that is lockable in the off position?

ETA: Just cracked open a code book and saw the a/c disconnecting means exception for lockable in the off position also has some b.s. about industrial processes. Stupid.


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## frenchelectrican (Mar 15, 2007)

manchestersparky said:


> I see this missed more often then not !
> I've even mentioned it to the EC on site when doing another inspection for them , and they still don't install one.


Hey Manchestersparky.,,

did the code do address for *both* indoor and outdoor disconnecting means for the split unit ? 

If so can ya run that code number if you are on '14 or '17 edition ?


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## B-Nabs (Jun 4, 2014)

I've only ever installed a disco on the outside unit and never been called on it. 

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## WronGun (Oct 18, 2013)

Is this shielded wire necessary ?! 

And why does It specify the use of stranded wire ?


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## drspec (Sep 29, 2012)

Ive never installed the disconnect for the indoor unit nor have I ran the wiring between the indoor unit and outdoor unit.
I run wiring to a disconnect and a whip to the outdoor unit and call it a day. Leave the rest up to the HVAC guy.


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## MTW (Aug 28, 2013)

We never install disconnects for the indoor units when we wire them, which is rare. The a/c guys certainly don't and they usually run the wiring (the special mini-split tray cable).


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## MechanicalDVR (Dec 29, 2007)

Going_Commando said:


> They don't because it is stupid and unnecessary.


I disagree.

There is no need to go find the condensing unit outside when you want to just work on the indoor unit.

Often there are banks of condensing units outside that aren't marked.

Not to mention needing a disconnect within sight of an HVAC appliance.


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## MechanicalDVR (Dec 29, 2007)

MTW said:


> We never install disconnects for the indoor units when we wire them, which is rare. The a/c guys certainly don't and they usually run the wiring (the special mini-split tray cable).


You must work around some serious hacks!


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## MTW (Aug 28, 2013)

MechanicalDVR said:


> You must work around some serious hacks!


Most hvac guys are complete hacks, especially the ones that do installation.


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## Going_Commando (Oct 1, 2011)

MechanicalDVR said:


> I disagree.
> 
> There is no need to go find the condensing unit outside when you want to just work on the indoor unit.
> 
> ...


Not my problem that the HVAC installer was too lazy to label things.


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## Dark Knight (Jan 6, 2016)

Going_Commando said:


> They don't because it is stupid and unnecessary.


Well said. Not to mention it looks like ass.


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## nrp3 (Jan 24, 2009)

What I noticed with the Mitsubishi I put in my house that directions were a poor translation and somewhat hard to understand as far as wiring went. I think vaguely mentioned something about GFCI protection, that it was suggested. I did UF from the outside to inside through a three pole switch for the disconnect. Provides some nice heat.


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## Dark Knight (Jan 6, 2016)

MechanicalDVR said:


> I disagree.
> 
> There is no need to go find the condensing unit outside when you want to just work on the indoor unit.
> 
> ...


Can't you just turn off the breaker? Both units are controlled from the same breaker which is near enough to the indoor unit to suffice, IMO. If there are banks of outdoor units, you're probably talking about a Multi-Plex which means there is a panel in every suite and close by.


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## MechanicalDVR (Dec 29, 2007)

Dark Knight said:


> Can't you just turn off the breaker? Both units are controlled from the same breaker which is near enough to the indoor unit to suffice, IMO. If there are banks of outdoor units, you're probably talking about a Multi-Plex which means there is a panel in every suite and close by.


No I'm not talking about a multiplex.

I'm talking medical offices, research facilities, schools/colleges, etc.

Why should I waste time searching a large office or building to find a breaker when I can just turn off the REQUIRED disconnect?


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## frenchelectrican (Mar 15, 2007)

Dark Knight said:


> Can't you just turn off the breaker? Both units are controlled from the same breaker which is near enough to the indoor unit to suffice, IMO. If there are banks of outdoor units, you're probably talking about a Multi-Plex which means there is a panel in every suite and close by.


Yes and no due some mini splits unit are multi split units., it mean it have main outdoor unit but there is few indoor units that is shared with the outdoor unit. 

that I have ran into more than once over here in my area ( Philippines ) and it kinda semi common over here.

but for single split unit the outdoor disconnect useally take care of that but once you get multi .,, then you have to add both outdoor and indoor disconnect switch next to the indoor unit(s). the reason why need indoor disconnect due there is few indoor units are tied to a outdoor unit and need a service disconnect there. ( some location allowed multipole snap switch for this purpose )


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## MechanicalDVR (Dec 29, 2007)

MTW said:


> Most hvac guys are complete hacks, especially the ones that do installation.


HVAC guys shouldn't be doing line voltage wiring.


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## frenchelectrican (Mar 15, 2007)

MechanicalDVR said:


> No I'm not talking about a multiplex.
> 
> I'm talking medical offices, research facilities, schools/colleges, etc.
> 
> Why should I waste time searching a large office or building to find a breaker when I can just turn off the REQUIRED disconnect?


this is why we do add both outdoor and indoor disconnect switch espcally with large building and I know one large store do have over 18 mini splits in there. so that why we need a local disconnect switch.


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## MTW (Aug 28, 2013)

MechanicalDVR said:


> HVAC guys shouldn't be doing line voltage wiring.


I agree but the reality is they do sometimes. But for the most part we do all the line voltage wiring. Pretty much the only time I see hvac companies do their own electrical is when they add a/c to a house that doesn't have it and no permits are involved.


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## Dark Knight (Jan 6, 2016)

MechanicalDVR said:


> No I'm not talking about a multiplex.
> 
> I'm talking medical offices, research facilities, schools/colleges, etc.
> 
> Why should I waste time searching a large office or building to find a breaker when I can just turn off the REQUIRED disconnect?


Ya, I agree, in a commercial building that would be a problem. I was thinking of MDU's as that's the only place I've ever installed banks of them. And I wouldn't have as much of a problem putting a disconnect in a commercial space as in a home.


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## nrp3 (Jan 24, 2009)

It's tough in office buildings that have been cut up so many times that panels can be hidden all over the place and feed other tenant spaces. One of the ones I work on was so convoluted and things shared, that management took over the electric bill for the whole building and billed by square footage.


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## MechanicalDVR (Dec 29, 2007)

MTW said:


> I agree but the reality is they do sometimes. But for the most part we do all the line voltage wiring. Pretty much the only time I see hvac companies do their own electrical is when they add a/c to a house that doesn't have it and no permits are involved.


Not that I've done much resi in the past but in the places I've worked if there were a couple HVAC trucks on the property an inspector would stop by looking for a permit more often than not.


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## MechanicalDVR (Dec 29, 2007)

Dark Knight said:


> Ya, I agree, in a commercial building that would be a problem. I was thinking of MDU's as that's the only place I've ever installed banks of them. And I wouldn't have as much of a problem putting a disconnect in a commercial space as in a home.


I have never been a resi guy since I became an adult and that is a long while.


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## Dark Knight (Jan 6, 2016)

frenchelectrican said:


> Yes and no due some mini splits unit are multi split units., it mean it have main outdoor unit but there is few indoor units that is shared with the outdoor unit.
> 
> that I have ran into more than once over here in my area ( Philippines ) and it kinda semi common over here.
> 
> but for single split unit the outdoor disconnect useally take care of that but once you get multi .,, then you have to add both outdoor and indoor disconnect switch next to the indoor unit(s). the reason why need indoor disconnect due there is few indoor units are tied to a outdoor unit and need a service disconnect there. ( some location allowed multipole snap switch for this purpose )


Interesting, I've never seen multi units like that.


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## Dark Knight (Jan 6, 2016)

MechanicalDVR said:


> I have never been a resi guy since I became an adult and that is a long while.


Are you saying Resi work is childs play??


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## Dark Knight (Jan 6, 2016)

MechanicalDVR said:


> HVAC guys shouldn't be doing line voltage wiring.


Around here HVAC guys get a limited electrical license with their gas ticket, 120 volts and 15 or 20 amps, so they can wire up furnaces when they install them.


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## MechanicalDVR (Dec 29, 2007)

Dark Knight said:


> Are you saying Resi work is childs play??


Nope, saying I haven't dealt with mini splits in a resi situation.


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## MechanicalDVR (Dec 29, 2007)

Dark Knight said:


> Around here HVAC guys get a limited electrical license with their gas ticket, 240 volts and 15 or 20 amps, so they can wire up furnaces when they install them.


I'd like to see some of their work, I bet it isn't beautiful.


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## macmikeman (Jan 23, 2007)

If it is not a dual zone or a tribune, I run the feed for the outside unit thru an adjustable switch box mounted on the inside near the fan coil unit , screwed flush to the unfinished wall depth, unbroken in the box and sent on down to the outside disco. I feel a lockable disco is good enough on the outside to cover the concern of shock to a workman on the fan coil side of the wall, but if an inspector is insistent then I just dig out the adjustable box behind the sheet rock and install a double pole switch. Now , turning off that interior switch kills power to the outside unit and therefore killing power to the inside unit as well. For dual zone, tribune, and quad unit compressors running two, three , or four interior fans I do something similar which is run the three wire control cable thru the adjustable switch box flushed flat into the interior wall and taped over with blue tape, then drywalled over.


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## telsa (May 22, 2015)

This thread was supposed to be about SPIT systems.

And yet it's been diverted into some pitiful thread about HVAC units.


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## Dark Knight (Jan 6, 2016)

MechanicalDVR said:


> Nope, saying I haven't dealt with mini splits in a resi situation.


Lol, I'm just messing with you.


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## Dark Knight (Jan 6, 2016)

MechanicalDVR said:


> I'd like to see some of their work, I bet it isn't beautiful.


That would be good money.


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## macmikeman (Jan 23, 2007)

telsa said:


> This thread was supposed to be about SPIT systems.
> 
> And yet it's been diverted into some pitiful thread about HVAC units.


Residential mini units are most commonly called mini splits because the compressor is outside and the fan coils are inside (split) . Doesn't refer to heating / ac split. That would be combination. I suggest you injest a spoon full of ginseng twice daily until that confusion goes away.


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## telsa (May 22, 2015)

Thanks doc.


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## B-Nabs (Jun 4, 2014)

telsa said:


> This thread was supposed to be about SPIT systems.
> 
> And yet it's been diverted into some pitiful thread about HVAC units.


We're not so different, you and I. 

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## WronGun (Oct 18, 2013)

I installed a disconnect outside and a service switch in the ceiling. This isn’t a wall unit it’s a ceiling unit. 

More about that shielded why.....

Is this common wiring ? I’ll need to pick this up in the morning 



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## frenchelectrican (Mar 15, 2007)

Dark Knight said:


> Interesting, I've never seen multi units like that.


I have see it pretty often espcally with larger minisplits escpally when they come in multi units.,

the inside unit will typically have a soilind to shut off the flow of freon if the unit dont call for cooling and the outdoor unit ( some models will change speed of compressor ) slow down or speed up depending on how many inside unit kick on.

I was in Gaisano store ( simuair to Wallmart store ) yesterday to replace the fuses for mini split ( one inside unit fan motor call a quits ) one of the Gasiano store did have 24 inside unit and 8 outdoor unit ( 3 ph ) so all the indoor unit do have a disconnect switch for safety reason. 

They are useally Mutiusbhi ( sp ) or Fuji heavy industries that is the two most common units I dealt over here.


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## Dennis Alwon (May 9, 2009)

MechanicalDVR said:


> Gee I'm surprised using nm in a wet location!


We actually converted the nm to carflex thru a T-11 box and used thwn. NC just passed an amendment which allows us to use up to 6' of nm cable outside in a conduit. So, in fact, we could run 14/3 out to the unit if it were sleeved in carflex or something.


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## MechanicalDVR (Dec 29, 2007)

Dennis Alwon said:


> We actually converted the nm to carflex thru a T-11 box and used thwn. NC just passed an amendment which allows us to use *up to 6' of nm cable outside in a conduit.* So, in fact, we could run 14/3 out to the unit if it were sleeved in carflex or something.


Highly unlikely in any install I've seen with the condenser on the ground and the indoor unit mounted directly on the opposite side of the wall you'd still have at least 8'-9' of conduit outside the building.

Most installs I've been involved with the units are much further than apart than 6' more like 20'-50' apart.


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## MechanicalDVR (Dec 29, 2007)

Dark Knight said:


> Lol, I'm just messing with you.


I know that resi installs can and are often done my semi trained semi house broken monkeys and that only fixing what they install involves skills.


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## nrp3 (Jan 24, 2009)

I'm sure the install side is vastly different than the service side of those things. Install side is pretty easy as long as your not running into length limitations of the line set.


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## macmikeman (Jan 23, 2007)

nrp3 said:


> I'm sure the install side is vastly different than the service side of those things. Install side is pretty easy as long as your not running into length limitations of the line set.


AC guys don't fix them. They just sell you another one when yours breaks down.


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## WPNortheast (Jun 4, 2017)

The money guys get for installing these things is insane...


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## Going_Commando (Oct 1, 2011)

macmikeman said:


> AC guys don't fix them. They just sell you another one when yours breaks down.


That's pretty much what I've seen? "Well, my gauges say its fine, so why dont we swap out the indoor unit and see what happens?


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## WronGun (Oct 18, 2013)

Update : 

I used the red wire for communication and it all went well.... 



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## sbrn33 (Mar 15, 2007)

Not to get back to the main subject but...
I have never put a disco on the inside unit and hopefully never will. It is just plain stupid and totally unnecessary. It is a fractional HP motor at most. Plus you will never have to touch the inside unit without having to check the outdoor unit. 
Normally I run the conduit and the AC guys run the cable from the inside unit to the outside unit.
I have spoken so we are done now.


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## WronGun (Oct 18, 2013)

sbrn33 said:


> Not to get back to the main subject but...
> I have never put a disco on the inside unit and hopefully never will. It is just plain stupid and totally unnecessary. It is a fractional HP motor at most. Plus you will never have to touch the inside unit without having to check the outdoor unit.
> Normally I run the conduit and the AC guys run the cable from the inside unit to the outside unit.
> I have spoken so we are done now.




This turned into a big point... it only took us an extra 10 minutes to install a service switch in the ceiling....

When I don’t know the exact wants of the AHJ , I just take the extra step as sometimes it involves more time flipping through the codebook or making calls to the inspector. 


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## fisher33 (Dec 5, 2017)

i agree with the three pole switching a box ... disconnect down below. I just installed 5 of these today, they are all on the roof, but they feed the IT rooms on each floor (5 floors). It is way too easy to install a disconnect down below for servicing means and labeling!


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## Spark Master (Jul 3, 2012)

The indoor unit is powered from the outdoor unit.... It's not like it's on it's own circuit... I've never seen a disconnect, resi or commercial.

I have seen HVAC guys stuff romex in seal tight, and run that from the outdoor unit, to the wall hanger.


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## lighterup (Jun 14, 2013)

The last one I did , single phase ...I only needed (1) 240 volt 20 amp
circuit , with an typical outdoor 30 amp disco.

The HVAC guys had a wiring harness that connected the out door unit 
to the indoor unit and they put their line set and that harness in a vinyl
gutter that went directly up above from the outdoor unit to the 2nd floor
where the indoor unit was installed.


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