mini split install

[EdT]

I'm just starting the installation of a couple of mini splits in my new building and I have a couple of questions that maybe someone has already dealt with. These are generic units, "hecho in China" and I chose them after careful consideration so let's not go off on a tangent. I am planning to run the wiring and tubing from the compressor INSIDE the wall rather than in a conduit OUTSIDE the wall as is often done on a retrofit. There is a power connection between the compressor unit and the indoor unit that is, for lack of a better description, a 25 foot extension cord (300V 3X14awg SJTW 105C) with flying leads that get attached to a terminal block at each end. I'm wondering if this type of wire is allowed INSIDE a wall or should I just swap it out for romex or something similar. Or perhaps running it in sealtite or rigid conduit would make it OK. Comments

 

[rickairmedic]

Ed every Mini Split I have put in simply used 18Awg thermostat wire for the run from the condensor unit outside to the air handler inside and it is run inside walls every day .

Rick

 

[EdT]

Rick,
Thanks for the response. There are three sets of wires on this particular unit and a mixed bag of advantages and disadvantages asociated with this approach.
1)There is a set of control wires betwen the units and these are, of course, low voltage and of no particular concern.
2) There is a "defrost wire" to signal the condenser to defrost itself should the need arise. Again, low voltage so no biggie.
3) There are the power wires that power the inside unit from the outside unit. For a retrofit application, this arrangement has some advantages, but since this is not a retrofit I want to run the wires inside the walls hence my question. I have some vague memory that it is not-code to use "extension cord" as permanent, covered up wiring.

 

[rickairmedic]

OK Ed I will buy that and in that case you are right on the extension cord in the wall. I would just go with Romex of the same AWG and put it in that way . All of the units I have put in the inside unit is actually powered of of the 18AWG T stat wire :O.


Rick

 

[sneezer41]

I have done this install several times, and the supplied wire is adequate. It is only powering the fan and electronics in the inside unit. couple amps max.

There is nothing wrong with upgrading, but I would not worry.

edit:

mine all only had a 4 wire, power[220] signal, and ground

 

[hidollartoys]

Per NEC 2005 code... Flexible cords are not permitted to be run inside walls, through holes in walls. attached to building surfaces, as a substitute for fixed wiring of a structure, ETC.... See 400.8 of NEC for additional. I have installed this type of system and the supplied "flexible" wiring to connect the inside and outside units is NOT suitable for running inside walls. You can substitute a "romex" type wiring of the same guage for the supplied "flexible" wire.

 

[EdT]

Thanks to all who have responded to my question. I wasn't concerned that the supplied wire was inadequate to the task, I was concerned that it doesn't meet code. I'm sure it would work just fine. So, I think I'll go ahead and just use some romex. Now, any good ideas for how to bring the romex out of the wall for connection to the outdoor unit. I think it will have to be insome kind of conduit, but not sure of the best way to interface romex with conduit. I don't think I can put it in conduit w/o stripping off the outside insulation and then I would have to carry that to a junction box accesible on the inside of the building and then from that run a piece of romex up the wall to the indoor unit. Or, I could run the conduit (sealtite or other flexible stuff) all the way from the outdoor unit to the indoor unit and skip the intermediate box and all that. This conduit would have loose wire inside Possibly (and ironically) stripped from the supplied cordset. Nothing is as simple as it appears at first glance!

 

[rickairmedic]

Ed Sealtite will work just fine for the transition from the wall to the outside unit . I would just slide the romex inside of it then slide it into the wall and attatch the ftree end to the outside unit . I would caulk it at the wall but thats about as far as I would go with it there . Romex will fit inside sealtite just fine .


Rick

 

[trythis]

they sell a romex style cable for this very commonly at home depot and lowes. It is wrapped in the same plastic sheath and not just exposed twisted wire.

 

[sneezer41]

Lets be clear, this is not building wiring, it is internal appliance wiring. It is the same wiring that would be used if it was in a pipe chase on the surface. It is part of a system, NOT attached to the breaker panel. I am assuming he is using the supplied cable not a bunch of random wires. this is not hiding a piece of zip cord in a wall and plugging it into an outlet, but part of an engineered system.

Stranded wire is superior in this app because of vibration.

 

[EdT]

Sneezer41,
I have had similar thoughts. The supplied cord is, arguably, "internal" to the system and happens to pass through the wall. It's similar to an interconnect inside a window unit. I guess I need to get ahold of my local inspector and see how he feels about it. At the end of the day his opinion is the one that counts.
Thanks for the input,
ET