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Thread: Air Conditioner connections

  1. #1
    Bronze Member
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    Air Conditioner connections


    When I did my training it was said that an air conditioner unit upto 16000 BTU can be supplied by a socket.

    I am have been asked to do the electrical for a 24000 BTU. The new air conditioners are a lot more efficient to give you an idea this 24000 BTU is a Samsung, 8 pole inverter unit and uses 8 amps for cooling and 7.7 for heating.

    I see no reason why I cant supply this unit from a socket circuit.

  2. #2
    Diamond Member AndyD's Avatar
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    If it's a high-wall split or in-ceiling cassette type a/c unit I'd treat it as a fixed appliance but I'd also look towards the manufacturers installation instructions for the supply requirements.


  3. #3
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    the afe way is to mount an isolator at ur unit condenser unit outside.Reason for that is that if any maintance need to be done to the unit a tech can switch it off there and no problem.To have it on a socket is not ideal as someone can be working on the unit and lets say the house owner's kids come home and the want to switch the aircon on and just plug it in.
    or at a office block normally the unit outside is far away and the office guy's just plug it in and switch it on.
    The other reason is that the normal Circuit breaker for a plug is not designed to handle the start up current of a it may pack up and then u sit with the problem.

  4. #4
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    I always prefer having a look through SANS 10142 before making assumptions

    The regulations talks in amps not BTU with regards to Aircons - Have pasted the section below and the requirement for the disconnector device. There are a couple of other references to Fix appliances and disconnection devices in the regulations but the 4 below basically cover the requirements.
    I have found that there are two points that everybody always seems to miss - It is the need to look at , that if it is classed as a motor and also that even if the fixed appliance has it own disconnector it still needs another disconnector as part of the fixed installation ( . Heating and cooling Dedicated circuits shall be provided for fixed space heating and
    cooling (air-conditioning units) that are rated at more than 16 A. There may
    be more than one unit on each circuit and the power supply to each unit shall
    be controlled by a switch-disconnector. The power supply to every fixed appliance, except luminaires, shall
    be supplied through
    a) a disconnecting device that disconnects both live conductors in a singlephase
    supply and all phase conductors in a multiphase supply, or
    b) a socket-outlet that is directly accessible at all times that any person is
    exposed to such appliance while the supply is on. In the case of a
    remotely installed appliance, the position of the disconnecting device
    shall be indicated by means of a notice in close proximity to or on the
    appliance. The disconnecting device shall be positioned
    a) within 1,5 m from the appliance, or
    b) in a distribution board (if the switch-disconnector is capable of being
    locked in the open position).
    Even where a disconnecting device is on the appliance, a separate
    disconnecting device shall be provided in the fixed installation to allow for the
    total removal of the appliance
    . Each motor shall be supplied by a manually operated
    disconnector or any other manually operated disconnecting arrangement
    such as a withdrawable circuit-breaker, a removable link, a fuse or by the
    removal of a plug from a socket-outlet, which provides at least the same
    isolating distance, for the sake of safety, as a disconnector that is
    a) readily accessible and mounted on or next to the motor, or
    b) visible from the motor, or
    c) lockable in the open position, or
    d) housed in a lockable enclosure other than a distribution board

  5. #5
    Diamond Member
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    A note with regards to Curve 1 or D curve breakers - In the past I always installed a slow curve breaker C1 or D curve...i have noticed that the new invertor A/C units make these breakers hum...I now fit a standard breaker suitably rated for the A/C unit.

  6. #6
    Diamond Member Justloadit's Avatar
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    With inverters, standard circuit breakers can be used, and no need to oversize, since the inverters implement soft start which ensures that the motors are never under a high current, there by reducing the current drawn from the supply. In the case of overload of motors, the inverters are so fast, the circuit breaker does not even flinch.

    The humming of the slow curve breaker, tells me that the inverters do not have built in PFC, and hence the high impulse currents which are transmitted to the supply under operation. Strange as this is one of the main issues SABS has with certification and power factor requirement.

    The circuit breaker in this case is purely for protection in the case of a catastrophic failure.
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  7. #7
    Gold Member Derlyn's Avatar
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    Hi All

    If the supply to a split unit is outside at the compressor, through a weatherproof isolator, is it necessary to also install an isolator at the control panel inside ? or will it be sufficient to attach a notice on the control panel inside indicating the position of the isolator as per a ?

    In the case of a remotely installed appliance, the position of the disconnecting device shall be indicated by means of a notice in close proximity to or on the appliance.

    Likewise, should the supply be at the control panel inside, through a double pole isolator, can one then attach a notice on the compressor unit outside indicating the position of the isolator ? or

    Must a split unit aircon have 2 isolators ? One at the control unit inside AND one at the compressor unit outside.

    Peace out .. Derek
    Last edited by Derlyn; 17-Jun-21 at 06:05 AM.

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