mini split cassette

[UncleRico]

I have a job and it has 15 mini split cassettes in ceiling. They do not have a unit switch or disconnect. They are all looped off of the same 208V circuit directly off panel. I know some of these systems feed the inside unit with DC from the main unit but this has its own AC circuit. Are they required to have a disconnect within site? At first I thought yes but I did a bit of reading and I'm not sure if it falls under 440,430 or 422. Some people are saying it's an appliance and it does not need one. Im also wondering if it even falls under 440 because is doesn't have a compressor. 440.8 says it considered a single machine but this has a separate circuit. 430 would require it but I don't know if 430 applies here.

 

[dm9289]

I have a job and it has 15 mini split cassettes in ceiling. They do not have a unit switch or disconnect. They are all looped off of the same 208V circuit directly off panel. I know some of these systems feed the inside unit with DC from the main unit but this has its own AC circuit. Are they required to have a disconnect within site? At first I thought yes but I did a bit of reading and I'm not sure if it falls under 440,430 or 422. Some people are saying it's an appliance and it does not need one. Im also wondering if it even falls under 440 because is doesn't have a compressor. 440.8 says it considered a single machine but this has a separate circuit. 430 would require it but I don't know if 430 applies here.

Looks like you stumped the world

 

[hbiss]

I have a job and it has 15 mini split cassettes in ceiling. They do not have a unit switch or disconnect. They are all looped off of the same 208V circuit directly off panel.

If they do not receive power from the condensing unit and are only connected by refrigerant lines and are powered by their own circuit from the panel, I would say you need to treat them like fan coil units. They each need to have a disconnect or be close enough to the panel so that the breaker can act as a disconnect.

Kind of unusual though. Do you have the manufacturer and model number?

-Hal

 

[dm9289]

If they do not receive power from the condensing unit and are only connected by refrigerant lines and are powered by their own circuit from the panel, I would say you need to treat them like fan coil units. They each need to have a disconnect or be close enough to the panel so that the breaker can act as a disconnect.

Kind of unusual though. Do you have the manufacturer and model number?

-Hal

I think these are a unit that fits in 2x2 drop ceiling grids, refrigerant lines is only connection from condensing.
Im a little stumped here also, would a breaker lock be OK if the unit is not within sight?

 

[hbiss]

I assume so but not positive since you say all 15 are on the same breaker. You could mount a 4 square box on each unit above the ceiling and install a two pole switch as a disconnect. It would be considered accessible, and anybody working on the unit would be up there anyway.

-Hal

 

[Ken_S]

The system you're describing is becoming increasingly more common. While I've haven't looked into the code requirements for them, the systems I've seen like this all had switches installed above the ceiling next to the units.

 

[Tulsa Electrician]

It peaked my interest. I looked up a five cassette unit. For this brand it has a breaker in the cassette unit. The power comes from the main unit.

Never wired one and wonder if the cable install would be covered under the NEC.

 

[hbiss]

It peaked my interest. I looked up a five cassette unit. For this brand it has a breaker in the cassette unit. The power comes from the main unit.

That's not what we are talking about here. The OP is talking about a system that uses 2'x2' (or larger) "lay-ins" that go in the ceiling grid. Those are called cassettes. Although the style of the indoor unit shouldn't make a difference with what you are talking about, (wall units) his are not powered from the main unit but powered by an individual circuit of its own. Hence the disconnect requirement on each unit.

-Hal

 

[GoldDigger]

That's not what we are talking about here. The OP is talking about a system that uses 2'x2' (or larger) "lay-ins" that go in the ceiling grid. Those are called cassettes. Although the style of the indoor unit shouldn't make a difference with what you are talking about, (wall units) his are not powered from the main unit but powered by an individual circuit of its own. Hence the disconnect requirement on each unit.

-Hal

Does each indoor unit have a thermostat and/or control wiring back to its outdoor unit? I am not sure how the system would operate without a power connection between indoor and outdoor. Mini splits with power supplied from outdoor unit to indoor unit, there is a third wire which, working together with the power wiring, supplies a (two way?) signalling connection between the units.

 

[augie47]

IMHO, it would be dependent on the HP of the motor. 430.109(B) allows the branch circuit disconnect to suffice for motors 1/8 HP or less.
Otherwise, add a switch.

 

[Tulsa Electrician]

That's not what we are talking about here. The OP is talking about a system that uses 2'x2' (or larger) "lay-ins" that go in the ceiling grid. Those are called cassettes. Although the style of the indoor unit shouldn't make a difference with what you are talking about, (wall units) his are not powered from the main unit but powered by an individual circuit of its own. Hence the disconnect requirement on each unit.

-Hal

Thank you

 

[hbiss]

Does each indoor unit have a thermostat and/or control wiring back to its outdoor unit? I am not sure how the system would operate without a power connection between indoor and outdoor. Mini splits with power supplied from outdoor unit to indoor unit, there is a third wire which, working together with the power wiring, supplies a (two way?) signalling connection between the units.

Dunno. Good question. That's why I asked for the manufacturer and model number so I could check it out.

I could imagine a number of these units in a large area where there is one central thermostat that turns on the condensing unit. Then each unit turns on when it senses the refrigerant flow or the temperature of the coil.

Or it could operate like a supermarket refrigeration system. The condensing units operate continuously and there are refrigerant solenoid valves in each unit controlled by a wall thermostat.

-Hal

 

[UncleRico]

Here is the nameplate