Mitsubishi ductless system question

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SmithBuilt

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This type of unit is split system. The outdoor unit feeds the indoor unit by 3-14ga wires. My problem is the instructions require a disconnect at the indoor unit to disconnect all three wires. How do I disconnect all three in a small box that will not look too bad. All I can think of is a 3ph disconnect but that will look terrible. Any suggestions appreciated.
 
Looking over my shoulder, I see a Mitsu ductless split. It has a 20 amp 120 volt breaker feeding the inside unit. next to the unit is a 20 amp disconnect switch. Funny how it looks like a leviton light switch though. I'll bet the other 2 wires are the neutral and ground.
 
bar beer, do you have a code reference I could use?

boater bill, this is a 240v system no neutral. The ground would be the 4th wire needed. according to the specs all 3 are current carrying.
 
The blower portion (in question) is actually fed from the CU outside if I understand correctly- this is the way all I have dealt with have been. That said- You have a disco @ the CU that disconnects the blower, IMHO, NEC satisfied. I do not believe that I can give you an article # that says you don't need it, but I am sure that with some research I along with others could supply an article that says you do. This is an interpretation thing to me. I do welcome other views.
 
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ok....sorry if this is a dumb response but I have never seen one of these actually...but could you not simply have a cord and plug on the inside unit and serve as the disconnection means?

anyway....just a DART into the dark..........what is the model number you are working with?
 
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Correction to my initial post.
The 3rd wire feeding the indoor unit is 12-24v. The directions show it to be disconnected also. However could I use 422.32 an appliance less than 1/8 hp. Then I could use the disconnect feeding the condenser as a lockable disconnect?

radiopet, The condenser feeds the air handler and controls it thru this feed. I suppose cord connection would be ok. Being it is 240v but if it was 110 the homeowner could plug it into a standard wall outlet then the condenser wouldn't be able to control the air handler. Still there would be the problem of the 24v wire it uses one of the 240v legs to complete it's circuit.


MSZ-A09/A12/A15/A17NA
http://www.mrslim.com/UploadedFiles/Resource/Install_MS_MSZ_MSYA09-17%20.pdf
 
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Mr. Smith-

Your O.P. says a disco IS required, the install manual provided says MAY be needed. Semantics? Maybe! Check w/ AHJ for true requirements- here I would be O.K. with the outdoor unit disco only since the outdoor unit is feeding the indoor.
 
Hmm......I notice it says * May be required......have you called your local AHJ to ask them if they would require this.

Just figured I would post the image for you so it makes it easier for the others to give comments on it for you.
 
I'm hoping to lead the AHJ in my direction, I know if I call and ask the answer will be it is required.

When I said "is required" I was referring to the three pole part not so much the disco.

Thanks for the help. I will now call the inspector and ask.
 
SmithBuilt said:
This type of unit is split system. The outdoor unit feeds the indoor unit by 3-14ga wires. My problem is the instructions require a disconnect at the indoor unit to disconnect all three wires. How do I disconnect all three in a small box that will not look too bad. All I can think of is a 3ph disconnect but that will look terrible. Any suggestions appreciated.
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It's been a LONG time, but in the late 1970's timeframe, we used SquareD 2510KO2 for 3 phase disconnects at a machine when the customer required; these look like heavy duty light switches. We actually used the NEMA1 enclosed version, 2510KG2, I believe. This is rated for 7.5HP@230, 10HP@460 or 575; there is a KO6 version good for 15HP att he higher voltages. It has 115 ratings, 2HP, if that is an issue. There are 2 pole versions as well. A link to them is http://ecatalog.squared.com/pubs/Motor Control/Manual Starters and Switches/2510CT9701.pdf for you.

I specified and installed a fair number of these; they are lockable and met the requirements of companies who required an individual lockable switch for each motor.
 
I have installed 15 of these units and I always put a fused disconnect on the unit outside and a 3 pole motor rated switch on the power coming from the unit outside. I install the motor rated switch right next to the fan inside the closet.
 
I have installed 4 of these in 4 different juridictions and put a pull out dico at the unit but have never installed anything at the blower. All have passed. This one manufacturer on the last unit I did included a 4 wire so cord which is intended to be run along side the line set and hard wired at both sides. I would not use this and my hvac guy was a bit pissed. Would have been hard wired at the blower extended up thru a recessed ceiling space thru the roof and then zip tied to the line set and run hard wired to the unit on the rooftop. I can think of about 4 violations right there. Anyhow I ran everything from the unit in pvc with nmfc at the unit and nmfc to a j box above the ceiling. I then distributed the controls to each of the 2 condenser fans with 12/3 mc and ran hard wired to each. Passed just fine,no disconnect.
 
SmithBuilt said:
This type of unit is split system. The outdoor unit feeds the indoor unit by 3-14ga wires. My problem is the instructions require a disconnect at the indoor unit to disconnect all three wires. How do I disconnect all three in a small box that will not look too bad. All I can think of is a 3ph disconnect but that will look terrible. Any suggestions appreciated.
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Something like these may work mounted through a standard metal blank wall plate
http://www.mcgillelectrical.com/CatalogProducts.asp?nProductsID=168
 
Split AC system with aux. heat

Split AC system with aux. heat

I am looking at a simular problem with a tri-zone heat pump unit with aux. heat of 800 watts in each of the three indoor units. All the information I get from the sales person is the two (2-each) 9K units require 25 amps each and the one (1) 12K unit needs 30 amps. They are all feed from the outdoor unit which is fused at 80 amps. The best I can come up with would be a disconnect in each room. But even at that what is protecting the wiring from the outdoor unit to each disconnect? I really wish the manufactures would be required to have the manuals on the web for easy access, with the scematics too.

Just spoke to the sales rep. and am told the indoor unit has fuses on the control board only. All he wanted to know is when we were purchasing the unit.
 
Tell him you will buy the unit when he supplies enough information.

I've trusted salesmen too much when it comes to spec'ing equipment. Paid for it too.

My situation worked out ok. The indoor unit falls below the 300va requirement to have a disconnect within site of an appliance. I is ok with a lockable disco outside for the condenser.
 
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The three indoor units are operated by remote only. According to salesman the smallest unit needs 25 amps. I will call their tech. support to see if I can get better info., the amperage rating seems high to me.
 
mallard duck said:
The three indoor units are operated by remote only. According to salesman the smallest unit needs 25 amps. I will call their tech. support to see if I can get better info., the amperage rating seems high to me.
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I too would be surprised if the blower unit requires a circuit rated for 25 amps:confused:
 
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