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Joined: Aug 2007
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If you can see the breaker from the AHU, you don't need a disconnect. Otherwise, you need some form of disco, whether it's a plug or a $20 HVAC disco switch or what have you. This applies even if the unit has a built-in breaker. Even a built in breaker/switch? That's a disco. No? If not why?
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Joined: Mar 2005
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Ah, 422.34 answers this. Yes, the built-in breaker counts as the disco, but only in one and two family homes. For apartments and commercial, there are other (easily met) restrictions.
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Joined: Jul 2004
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I suppose we could go to the installation manual for the machine Harold referenced http://www.docs.hvacpartners.com/idc/groups/public/documents/techlit/38h,q_40q-1si.pdfIt is a mini-split that feeds the air handler directly from the condenser but it does use 208/240 on the interconnection cable. My LG does this with low voltage. The manual does not say anything about a disconnect at the air handler and the servicing instructions say you should turn off the outside disconnect when servicing the equipment. The fan is listed at 53w so it is less than 1/8HP and it might fall under 430.81(A) Would a disconnect, not called for in the installation instructions be a 110.3(B) violation? 
Greg Fretwell
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This is in Harolds' home. He is a 'Qualified person.  I see some 'Devils advocating' here.  (I see your point)Thanks for pointing this out to me.
Last edited by leland; 02/25/09 04:43 PM. Reason: devils advocate
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Greg, Sorry for not getting back sooner. There have been several styles of air handlers (AHU)that I see. The one in particular is 240 volt, 15 amp feed. The motor is tiny and I doubt if it even pulls 1-2 amps. (I don't have the paper work in front of me) It is not powered from the outside unit and it is not in sight of any circuit breaker. My question would be is a "snap switch disconnect" be required along side of the AH on the wall or could a breaker lock be the "Disconnect" for this AH. As for "Devils Advocate", I will explain later.
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The Carrier mini-split they are selling on that link you posted a while up thread is fed via the condenser. There is no separate feed to the air handler if the installation instructions are right.
The largest optional blower is 53w or about 0.22a.
The 15a @ 240 is the whole thing, condenser and all and it still doesn't use much of it. The compressor is 4.7a RLA and the condenser fan is 0.8a.
My 9kbtu LG will run on 120v 15a and the condenser is so quiet you barely know it is running standing right next to it.
Greg Fretwell
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Yes the AH would need a disconnect.
Most of these that I have done have the switch built in (Sanyo).Both 120 and 240 V models.
The breaker would still need to be 50' and With in site. I'll stand by this.
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You will be presented with a brown, a blue and a black along with the green/yellow ground. Which wires get "disconnected"?
You will get no guidance from the installation instructions since they don't call for a disconnect.
Would adding one be a 110.3(B) violation?
All of this wiring is way past where the line cord enters the machine (in the outside unit)
A hint on the top question. If you hooked this up with 14-3 wg Romex without reidentifying the white it would be a 200.6 violation
As a side note, do you require a disconnect for ceiling fans?
Greg Fretwell
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Greg,
The contractor gave me the paper work for this particular unit. It is a Carrier BNC/BNQ 024,030,036 Duct Free System ( Not sure which unit he is using) but the wiring diagram just shows 3 wires (1 Cable) to the inside unit. L1 (Brown) L2 (Blue) and Gray/yellow ground, then it shows it going to a Mains AC supply 208/230 VAC.
It will be mounted up high in a rec room above the door into the room. The wiring diagram doesn't show any on/off switch on the unit itself. There is a wireless remote control that goes with it in the room.
The full load amp says 0.6 amp. I don't even see a HP rating for this little motor. It is a single phase machine.
The installer says that he never installs a disconnect or snap switch for any AHU that he has installed. He thought that a breaker lock would satisfy the disconnect rule.
The feed (Breaker) will start at a sub panel in the basement, so the breaker will not be in sight of this unit. The Air Compressor will be outside under a deck and it will have it's own separate feed (Breaker) and a pull out AC disconnect.
Sorry if I am making this small job seem so difficult to figure out. I am just at a different opinion than a fellow colleague of mine. LOL That is why I wanted it on screen.
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Joined: Jul 2004
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I was wrong The installation book I referenced is for the QNC/QNQ and it shows 4 wires that go back to the condenser. I just looked at your unit and it does in fact have a line voltage connection. http://www.docs.hvacpartners.com/id...2618916-D&HighlightType=PdfHighlightI was really surprised that this thing used line voltage at all. Most I see use 24v for the air handler.
Greg Fretwell
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