Rooftop AC unit wiring

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iwire

Moderator
Staff member
Location
Massachusetts
My choice is cable or flex all the way but I believe the NEC defines that space as an enclosure and I could run open conductors.
 

Smart $

Esteemed Member
Location
Ohio
Your wire will be in the plenum area so no not legal.

...
My opinion would be the only argument preventing the open wiring in the unit would be Jim W's that the space might be considered an air plenum.
The condensor compartment intake is outside air and discharge is to outside air. IMO, this would not be "part of the air distribution system" per the NEC definition of plenum.
 

chris kennedy

Senior Member
Location
Miami Fla.
Occupation
60 yr old tool twisting electrician
The fpn after 'Enclosure' says see Table 430.91 for examples of enclosures.

Those are examples of enclosures, but by definition a fence or 'the case or housing of apparatus' is also an enclosure.

BTW 430.91 has been moved to 110.20 in the 08.
 

Jim W in Tampa

Senior Member
Location
Tampa Florida
The condensor compartment intake is outside air and discharge is to outside air. IMO, this would not be "part of the air distribution system" per the NEC definition of plenum.

If wiring is not in the plenum area then i have no issue with open wiring and will run it that way. Perhaps i miss understood OP. I did have 1 of my men not follow my instructions and run thru the air chamber. Made me look stupid when the AC guy caught it. What upset me the most was he was also one of our crew leaders and even gave him a helper. Ended up redoing it myself. As always RTU was about 500 feet from the ladder, real pain in the ---
 

Smart $

Esteemed Member
Location
Ohio
If the RTU has an internal disconnect, do you still pipe it in?

I vote for free air.
In my experience, integral disconnects are within an elctrical/electronic control compartment. I've always run conduit to the control compartment, and really hadn't considered any pros or cons to doing so.
 

cadpoint

Senior Member
Location
Durham, NC
A couple of pictures of this free wire sure would show something... :)

I can't go with in thought, and tend to disagree of this "free wire" style, I guess I'm getting old...

:)
 
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