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I’m planning to replace my old central forced air HVAC with mini split systems, but for a number of reasons, it will be more than a single multi-zone compressor. In that regard, am I required to have a dedicated branch circuit to each compressor, or can I run a single (appropriately sized) branch circuit to two or more compressors (assuming each one has its own disconnect)?

The main reason for this is the lack of room left in my breaker panel, and each unit typically requires two poles (the most efficient units are 240 V). It also makes the wiring effort easier.

Even if each unit has a rated maximum service breaker, it seems a disconnect with a breaker in it would address this, right?

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  • It is the amps that will decide. The breaker in the panel decides, but if putting in new circuits, can use larger wires and breaker, and then split the circuit down to size. It will probably be better to add a sub panel to have more breaker spaces. Think each mini split must be on it's own circuit
    – crip659
    Commented Aug 2, 2022 at 23:48
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    @crip659 - All mini split systems require a dedicated circuit to supply power to the system. Two minisplits cannot share one circuit. Also, a disconnect box is required by code to be installed near the outdoor unit Commented Aug 3, 2022 at 0:17

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All of the mini split system I've worked on have required dedicated circuits. Think about installing a sub panel out by the compressor locations and feeding it from your main panel. From the sub panel you use individual breakers and circuits sized for each compressor.

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I cannot say that all mini splits require a dedicated circuit but that is easy to get around.

Using the existing feed, install a small NEMA 3R panel that has 5 breaker positions. If both mini splits are within 50’ and can see the small panel, add a lockout clip for each mini split and you have the required disconnect and dedicated circuit.

I have used this method many times, including my own home. The small “spa” panel having a circuit for each mini and a circuit for the service or convenience receptacle works within code provided you have a 4 wire feeder.

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  • Great point about the "line of site" from compressors to breakers so they qualify as disconnects. I implied it but didn't define it.+
    – JACK
    Commented Aug 3, 2022 at 20:09

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