Another disconnecting means on mini splits thread...

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1ab1

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SFR, Los Angeles. Owner wanted an 8-unit Mitsubishi mini split system. Inspector insisting on a disconnect for each interior unit, despite the electrician offering a lockable disconnect on the outdoor unit which powers all of the indoor units (indoor units are that 3 conductor 110V system that carries power and data from the outdoor unit). We also offered to install the disconnects in the ceiling cavity adjacent to the indoor units (ceiling cassettes) so that they are visible once you remove the grille cover. Removing the grille cover is cosmetic, the electrical connections and insides of the unit are still inaccessible without removing further cover plates from the actual unit. Electrician went back to inspector with "440.14 Location. Disconnecting means shall be located within sight from, and readily accessible from, the air-conditioning or refrigerating equipment. The disconnecting means shall be permitted to be installed on or within the air-conditioning or refrigerating equipment" but he is saying that "from his training" we cannot locate the disconnect the way we are proposing. Curious what the group's consensus is. From what we can tell LADBS has not issued a bulletin around this, as other jurisdictions have.
 
Someone else may know otherwise but I'm not sure there has yet to be a direct definite answer from the NEC. Many feel the interior unit is covered by Art 422 and 422.31 would generally not require an interior disconnect if the exterior disconnect is lockable. Others seem to base the decision on Art 430 and feel 430.109 exempts an interior disconnect.
 
1ab1 said:
SFR, Los Angeles. Owner wanted an 8-unit Mitsubishi mini split system. Inspector insisting on a disconnect for each interior unit, despite the electrician offering a lockable disconnect on the outdoor unit which powers all of the indoor units (indoor units are that 3 conductor 110V system that carries power and data from the outdoor unit). We also offered to install the disconnects in the ceiling cavity adjacent to the indoor units (ceiling cassettes) so that they are visible once you remove the grille cover. Removing the grille cover is cosmetic, the electrical connections and insides of the unit are still inaccessible without removing further cover plates from the actual unit. Electrician went back to inspector with "440.14 Location. Disconnecting means shall be located within sight from, and readily accessible from, the air-conditioning or refrigerating equipment. The disconnecting means shall be permitted to be installed on or within the air-conditioning or refrigerating equipment" but he is saying that "from his training" we cannot locate the disconnect the way we are proposing. Curious what the group's consensus is. From what we can tell LADBS has not issued a bulletin around this, as other jurisdictions have.
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Tell him article 440 is for things with hermetic compressors, it says so right in the scope. The indoor unit does not have a hermetic compressor.
 
I have a new ADU with a MRCOOL 4th Gen DIY Multi-Zone installation. At final inspection LADBS inspector said I needed local disconnects by the air handlers. I've been researching and trying to prove him right or wrong. There is lots of talk about the topic but I see no DEFINATIVE answers.

It would be nice to see OP state if he ran with the given advice and if it worked or not.
 
Ended up escalating p high up the chain and they all insisted we add the disconnects. Suppose we could always remove them later 🙄
 
p.s. Do you mind sharing what you used and how you did... just simple terms. My electrician (literally just left the building) is still wrestling with how to open up the air handlers to interrupt the electrical for the switch. Our current plan is to simply install a decora style 2 pole "light" switch withing a few inches to the side or below the air handler. Is this how you did it? If you have easy access to a picture of the finished work that would be great too! TIA!

(I have reached out to MRCOOL support for any wiring diagrams and recommendations they might have. Hoping for a response from them tomorrow.)
 
MA is usually pretty strict. I used to use a 3 pole (Leviton motor switch) toggle switch to break the two hot legs and the signal wire from the outdoor unit. My feeling was it is a motor driven appliance and needs a disconnect.

But MA has ruled they are not required. Subject to interpretation in different locations, I guess.

@rc/retired

You can mount a box just under the head in the same stud bay as the pipe opening through the wall. Most mini splits these days are wired with TC cable. That way you fish the wire down to the electrical box through the switch and back up to the head.


See the attached. You can buy just the switch and flush mount it like any other switch or buy it with the enclosure and surface mount it. I did both depending on what location it was in
 

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Eddie702 said:
See the attached. You can buy just the switch and flush mount it like any other switch or buy it with the enclosure and surface mount it. I did both depending on what location it was in
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That one with the big red handle is probably what your inspector wants. Right in the middle of the bedroom wall. From his training, of course. 🤯

-Hal
 
The Mr. Cool product has in it's installation manual showing an "air break switch" at the air handler unit, but has no means to connect one without disassembly of the already prewired air handler. In addition to that, the MC, coolant, and drainage lines all prewrapped in a design to just sleeve through the wall own to the compressor, where only at that end are they separated.
They do make a switch that suppose to comply if only the design would allow for access to the wiring at air handler without total disassembly.

Air break switch
 
440.12(B) would seem to allow the main unit disconnecting means to disconnect the air handler as well.
But, the "within sight" requirement allowance if "lockable" does not seem to apply per 440.14 with the added wording of the exception "Where the disconnecting means provided in accordance with 430.102(A) is lockable in accordance with 110.25 and the refrigerating or air-conditioning equipment is essential to an industrial process in a facility".

So the allowance of 440.12 would seem to be useless in any location other than for an industrial process.
 
electrofelon said:
Did he cite a code section?
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Nopers. Even though he is the "Senior Building Mechanical Inspector Code Enforcement"; i.e. inspectors supervisor, I did tell him I was going to research it to verify if he was right or wrong. Of note, he's an inspector exception as he's personable and reasonable.

Fred B said:
The Mr. Cool product has in it's installation manual showing an "air break switch" at the air handler unit, but has no means to connect one without disassembly of the already prewired air handler. In addition to that, the MC, coolant, and drainage lines all prewrapped in a design to just sleeve through the wall own to the compressor, where only at that end are they separated.
They do make a switch that suppose to comply if only the design would allow for access to the wiring at air handler without total disassembly.
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You are right on point. This is the problem. It appears the whole air handler unit needs to be taken apart to interrupt the power and route locally to the required disconnect; i.e. it's not designed to do that even though the manual mentions it might be required. This is a DIY kit designed to be super easy and basically everything snaps together. Here's a pic of the cabling. Cutting the electrical cable with it's press on connectors and finishing shield just isn't vey DIY.

I haven't heard back from MRCOOL yet with any of their instructions/guidance/suggestions/answers. Considering all the NEC codes mentioned it makes no sense to me that they would make this kit out of compliance with standard code and be able to sell it. (I've read in other threads that some states have made stated exceptions to spit systems, but it wouldn't make business sense for MRCOOL to target for sale these units to only 2-3 US states!) The California ADU market is booming. I talked to the owner of a HERS inspection company and he said they majority of their business for the last couple years is ADUs at almost 100/mo. Typically that's a lot of garage to ADU conversions where ducted forced air to a 500 or 600 sq ft space doesn't make much sense financially and mini splits are a great affordable solution. MRCOOL must be getting hit with this problem constantly and realistically should have a solution; though that solution is probably buy the pro kit and have a pro install it.

I will update here as things progress. I'm hoping for a response from MRCOOL along the lines that the kit isn't designed for a local disconnect and that opening the air handler will void warranty blah blah, then I'll go bounce all this off the inspector and point out that the outside disconnect is LOTO can be locked out in off position. Hopefully he'll than agree to pass the inspection as is. FINGERS CROSSED!
 
augie47 said:
Someone else may know otherwise but I'm not sure there has yet to be a direct definite answer from the NEC. Many feel the interior unit is covered by Art 422 and 422.31 would generally not require an interior disconnect if the exterior disconnect is lockable. Others seem to base the decision on Art 430 and feel 430.109 exempts an interior disconnect.
Click to expand...

I've put this in my "argument box" as well. Waiting though to get my response from MRCOOL.
 
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