a few mini split observations

Status
Not open for further replies.
electrofelon

electrofelon

Senior Member
Location
Cherry Valley NY, Seattle, WA
Installed a few mini splits today. The real interesting thing was two of the conductors to the indoor unit were common with the L1, L2 supply conductors. I had never seen that before. Seems like that could throw another wrench in the discussion of these interconnect conductors, protection, disconnection, etc. These were daiken. I think they are Chinese. A different brand on site (air conn) had one of the three interconnect conductors labeled as a neutral. You dont see that much. I know on the Mitsubishis, all three are ungrounded as a metered them once to try to see if I could get away with a two pole switch (that location required the indoor disco).

The other interesting thing was the HVAC company supplied coated MC cable for the interconnect wiring method. First time I have seen that in the wild, its nice stuff I like it. Rated for direct bury, wet, and CT use.
 
Dennis Alwon said:
And in that thread there was a discussion that a mini split was considered one unit and a disconnect was not required on the inside unit-- according to some cmp members
Click to expand...

This in Washington state. There is no specific amendment requiring it. In the seattle area they do not require it, but seem to in the east side of the state.
I got hit for it once, I don't remember the sections called out, but it was several things from 430 and 440. They also required labeling on the units indicated where the other one was. They also supported that with a code citation, but I don't remember what it was either. This job is 270 miles for me, not worth the fight.
 
Well, this is how I interpret mini splits with regard to the inside unit disconnect...

Article 440 has rules on circuits supplying HERMETIC refrigerant motor-compressors and for any air-conditioner or refrigerant equipment that is supplied from a branch circuit that supplies a HERMETIC refrigerant motor-compressor...see 440-1

So...given that the indoor unit of a mini-split AC system does not have a HERMETIC motor compressor, it is not subject to the rules of article 440

440.3 tells me to look at OTHER ARTICLES and 440.3(B) directs me to look at 422,424 and 430 for air-conditioning equipment that does not incorporate a HERMETIC refrigerant motor-compressor.

I can rule out article 424 because the indoor head of the mini-split air-conditioning system is not a fixed electric space heating unit.

Article 422.3 guides me to look to the requirements of article 430 for motor operated appliances and article 440 for HERMETIC refrigerant motor-compressors. 422.10(G) again tells me to go to 430 for motor-operated appliances and 440 for HERMETIC type equipment (for overload protection).

OK...422.3 sends me to article 430 for motor operated appliances and I look at 430.109(B) in Part IX Disconnecting Means because the motor in these indoor heads is less than 1/8 horsepower and the branch-circuit overcurrent device shall be permitted to serve as the disconnecting means. The circuit breaker must be lockable if not in sight as required by 430.102(B)(2) exception..."lockable in accordance with 110.25"... I think we can consider the outdoor condensing unit with the HERMETIC motor-compressor the Controller of the indoor head unit and follow 430.102(B)(2) and use a lockable outdoor disconnecting means to comply with the disconnect requirement for the indoor head unit.

Unless the installation instructions with the mini-split AC system has a MANDATORY requirement for a disconnect by the indoor head unit...then 110.3(B) must be followed. I know Mitsubishi has taken any mandatory language for a disconnect by the indoor head unit out of their instructions.
 
Status
Not open for further replies.
Top