connection cable for spilt unit

[afeef]

the cable connecting the indoor unit with out door unit of split type air-conditionar consist of 4 core, my inquiry is:
-if 3 cores is for :live,nutral,earth connection,what is the 4th core for?
-what is the size of each core in mm?
thanks and regards to all
afeef

[superswill]

the forth core would be the signal,a fluctuating voltage depending on the kit,also the cable size should be based on cable lenght

[afeef]

the length of cable is the same of refrigerant piping, it came with the split 5 meters length, but can be extended till 15 m, the controll of the compressor is done by the live or the neutral core as the signal transmited from thermostate mounted in indoor unit ,the compressor amps is around 12 A
thanks superswill

[Electrocoolman]

Hi Afeef,
Depending upon the type of unit (basic or Inverter), the 4th wire will be used for different types of control purposes.
Might be reversing valve on a basic unit or in case of inverter, it is used in conjunction with the neutral to form a signal bus which allows communication between indoor and outdoor units.

[malik55]

Afif
Normally forth wire is for compressor on off signal to the condensing unit, be careful some split units also works on D.C Signal and 2 wire +/- comes from indoor unit, When in doubt alway check the drawing and electrical circuit before to connect on supply. You can use 2.5mm 4X1 PVC Cable for the same,
malik55