Interconnecting/Comms cable

[marc5180]

Hi guys,

Historically we’ve used either SY cable or NYY cable for our interconnecting cable, with CY for our Comms.
However I’ve become aware that these are no longer acceptable because SY isn’t IP rated and NYY/CY doesn’t have the armoured sheathing, is this correct?

If so what type of cable should be used instead?

[frank]

Hi Marc
What makes you think that the interconnect has to be either IP rated or have an armoured sheath?
I've never come across a site specification that requires either?


For most brands, the interconnect has both power and comms. With VRV and VRF the comms are separate from the power, as you know.

Look forward to learning from your answer ��

[marc5180]

Hi Frank,

Sorry for the late reply.

We've recently been told to stop using SY/CY cable because it doesn't conform to BS standards, the BS standard that it refers to is BS7671.

After some digging, this is what I have come to -

SY cables are covered by the relevant IEC publication and are widely used in Europe, VDE0250 BSEN/IEC 60332-1.
However, some seem to think that they are not permitted in the UK under BS7671 but it seems that this is not the case, they are simply not listed, (hence the confusion) as they are used for machine applications in this country, rather than for fixed wiring.
Mains Power to AC units (ie fixed wiring) should be Class 1 or Class 2 cable, with the requirements being basic insulation and earth.
SY cable is Class 5 and should not be used for fixed wiring, so in replace of armoured cable from distribution board.
SY cable is normally ran between the condenser and indoor unit, along the route of the pipework and is ideal for what it was designed for and that is control.

I believe at least one of the SY manufacturers are attempting to gain a BS kitemark to stop the confusion on this going forward.