Mini Split Installation - Electrical Question

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Old 01-26-18, 08:42 AM
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Mini Split Installation - Electrical Question

Morning all,

I am installing a Pioneer mini split in my garage workshop. I will be doing most of the installation myself and an HVAC tech will do final connections and vacuuming of the system. My question is in regards to how to get the electrical to the outside unit.

I have a subpanel in my garage which is on the opposite wall where the unit will reside. All of my electrical in the garage is surface conduit so I plan on running emt up the wall, across the ceiling and then through the other wall and down to the unit. Once outside I will transition the conduit to pvc. Can I run normal thhn in conduit outside or is there a different wire for outside use?

Also, the hvac guy said I could run the electrical bundled with the lineset so I would only have one run on the outside of the house. This seems more complicated. From my understanding, if I did that, I would need to transition from thhn inside the garage to some sort of outdoor cable. Seems like it might be more trouble than it's worth.

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Old 01-26-18, 10:53 AM
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Can I run normal thhn in conduit outside or is there a different wire for outside use?

You must use THWN wire outside, BUT.......I have never seen THHN wire that wasn't dual rated as THHN/THWN. As long as the wire has the THWN designation, you are fine.


the hvac guy said I could run the electrical bundled with the lineset so I would only have one run on the outside of the house.

That's the way some HVAC guys do it when an electrician isn't involved. I would follow your first plan to feed the required disconnect which the HVAC guy may not have been planning on. From the disconnect to the unit you could use non-metallic liquid tight flexible conduit bundled with the lineset.
 
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Old 01-26-18, 11:56 AM
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BTW, you can stick with EMT outside as long as you use raintight fittings. You don't have to switch to PVC on the exterior of the building.
 
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Old 01-26-18, 12:52 PM
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Originally Posted by CasualJoe View Post
You must use THWN wire outside, BUT.......I have never seen THHN wire that wasn't dual rated as THHN/THWN. As long as the wire has the THWN designation, you are fine.





That's the way some HVAC guys do it when an electrician isn't involved. I would follow your first plan to feed the required disconnect which the HVAC guy may not have been planning on. From the disconnect to the unit you could use non-metallic liquid tight flexible conduit bundled with the lineset.
Thanks for the reply.

I was looking online for THWN and it seems that finding it by the foot might be a problem. What if I ran conduit to the wall and then ran the wire down in the wall and into the disconnect? How would I transition from running the wire in conduit (TNNH) to running it in the wall (Romex)?

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Old 01-26-18, 12:55 PM
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Originally Posted by ibpooks View Post
BTW, you can stick with EMT outside as long as you use raintight fittings. You don't have to switch to PVC on the exterior of the building.
Thanks. I'll have to check with my local code people. I've heard that they dont like EMT on the outside.
 
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Old 01-26-18, 12:59 PM
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Bring the cable into the back of the disconnect. Switch methods from the disconnect to the unit.
 
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Old 01-26-18, 01:19 PM
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There is an electrical cable that connects the outside unit with the inside one. Maybe it is that one that the hvac guy said could run with the lineset?
 
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Old 01-26-18, 05:44 PM
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I was looking online for THWN and it seems that finding it by the foot might be a problem. What if I ran conduit to the wall and then ran the wire down in the wall and into the disconnect? How would I transition from running the wire in conduit (TNNH) to running it in the wall (Romex)?

If you are willing to fish the wire down the inside of the wall, just use NM-B cable (aka Romex) all the way and enter the back of the disconnect like PCBoss said.

I was looking online for THWN and it seems that finding it by the foot might be a problem.

Just look for THHN. When you find it I am confident that you'll find it is dual rated.
 
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Old 01-26-18, 06:47 PM
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Originally Posted by CasualJoe View Post
If you are willing to fish the wire down the inside of the wall, just use NM-B cable (aka Romex) all the way and enter the back of the disconnect like PCBoss said.




Just look for THHN. When you find it I am confident that you'll find it is dual rated.
Ah, yeah, I looked into it a bit more and the THHN I have on hand is also THWN.

In regards to the romex, I am trying to decide if I want to have conduit on the outside of my house.

Thanks for the replies, everyone.
 
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