Control or branch circuit

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nickelec

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On Ductless mini split AC systems.

All the conductors from the rooftop condensing unit to the blower unit inside the apartments considered a branch circuit or control wiring.

I'm pretty sure they are considered control wiring

I just got violation for the HVAC contracted running number 14 AC cable. In New York City number 14 is not allowed for branch circuit wiring My argument is that it's not a branch circuit what does everybody else think

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Does the inside unit receive its power from the outside unit? I’d call that branch circuit wiring. If the inside unit was fed independently, with its own branch circuit, and the wires between the two units were strictly communication, then I would call it control wiring.
 
Choice_Gorilla said:
Does the inside unit receive its power from the outside unit? I’d call that branch circuit wiring. If the inside unit was fed independently, with its own branch circuit, and the wires between the two units were strictly communication, then I would call it control wiring.
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Look at it this way. Control circuits are covered in article 725 (2023 breaks them up into multiple chapters). If it fits in article 725 it is a control circuit.

Control Circuit. The circuit of a control apparatus or system
that carries the electric signals directing the performance of
the controller but does not carry the main power current.
(CMP-11)
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Note what I bolded.
 
petersonra said:
Look at it this way. Control circuits are covered in article 725 (2023 breaks them up into multiple chapters). If it fits in article 725 it is a control circuit.



Note what I bolded.
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I'm not looking at my code book right now, but when you have a "control" transformer stepping 480 incoming to 120 and it runs a fan to cool the unit, what is that wiring called?
 
Strathead said:
I'm not looking at my code book right now, but when you have a "control" transformer stepping 480 incoming to 120 and it runs a fan to cool the unit, what is that wiring called?
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What size transformer?
Does the wiring leave the enclosure,or is the fan internal?
What type of protective device is on the transformer secondary?
 
A mini split has exactly the same power and control wiring as a 120v smoke detector system, which is a 2-wire branch circuit and single conductor for control (or interconnect)

In the pic, it's L1, L2 for power in, and also L1, L2 to the indoor unit (or L1, N for 120v units)Screenshot_20230705_142816_Chrome.jpg
 
We have had a quite a few threads on these. On most consumer grade / residential units there is just a tap block in the outdoor unit allowing you to extend the branch circuit and add the control wire as the 3rd wire to supply the indoor unit(s).
At that outdoor unit there is no additional or supplemental overcurrent protection at the tap block to supply the indoor unit wires.

There probably is some type of overload protection of the blower motor that protects a smaller 14 AWG from overload, hence it is allowed to have the 14 on a 20 or 30A breaker.
 
The unit inside is being feed coolent from the main unit outside and inside unit is only blowing and ocilating. It’s not the main sorce of current for that ul listed equipment.
Going off post three comments
 
The way to test if its a control circuit is if you could manually hold in a contactor and turn the indoor blower on. The indoor blower would then be getting its main power elsewhere.
Side question why does NYC require a minimum size of #12? Is that a real code ?
 
Presumably the circuit conductors to the indoor blower motors fall under 430.53(D)
 
tortuga said:
Side question why does NYC require a minimum size of #12? Is that a real code ?
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I don't know anything about New York, but one municipality here in the Kansas City area (Smithville, Missouri) used to require minimum #12

I haven't done any work there in forever, so I don't know if it's still that way. But I'm sure the reason is that there is one guy who thinks he knows more than everybody else.
 
petersonra said:
I would say more likely they fall under whatever the UL listing is for that particular piece of equipment if it is supplied with the equipment..
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HVAC equipment is not required to be UL listed. It would be a sad day if it were, as HVAC people already have to deal with two or three other codes, and they frequently need to customize installs.
 
At the risk of stating the obvious, they must have decided it was too easy to start fires, likely to the use of portable electric heaters, window A/Cs, hot-plates, etc.

I have been involved with such fires, even when properly protected.
 
LarryFine said:
At the risk of stating the obvious, they must have decided it was too easy to start fires, likely to the use of portable electric heaters, window A/Cs, hot-plates, etc.

I have been involved with such fires, even when properly protected.
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Could be, in the NYC code its right in there with the section on voltage drop.

I'd say then at least allow a "lighting only circuit" to be 14..
 
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