Is the interconnecting cable between outdoor and indoor AC units classed as a control cable or power cable?

Could be either ... or both.

It's certainly part of 'machinery' as defined in the Supply of Machinery (Safety) Regulations, and therefore not completely in the scope of BS 7671 ...

David Alcock said:

To another point on the design of the machine, it's also a requirement to design the installation and certify it, along with conplying with the UK regulations

With respect, you seem very reluctant to specify the standard or even law against which you are certifying compliance. Why is that please?

There are lots of regulations to comply with, BS7671, BS 5839, HTMs, and lets not forget the EAWR and CDM

AJJewsbury said:

Be careful with those cable specs - H only means it's a harmonized type, 05 or 07 the voltage range - so nothing there specifies UV resistance at all.

That's why you have to use the relevant part of BS EN 50525 series ... it should achieve the same thing, but in the UK we'd certainly owant BS EN 52525 series.

Some makes of HO7 will be more or less UV resistant - its the letters that follow that matter.;-) 

UV resistant Look out for third letter "N" without trailing qualifier numbers

(See https://www.peakcables.co.uk/european-system-cenelec-codes/ for a fuller cable decoding of the system or even 

https://myelectrical.com/notes/entryid/228/harmonised-cable-codes-and-colours 

Then see https://myelectrical.com/notes/entryid/178/cable-insulation-properties for the chemical and physical properties of most common insulation materials.)

 Polychloroprene (brand name Neoprene synthetic rubber) on its own is rather better than say  PVC,  or indeed un-stabilised polypropylene or polyethylene, but even so  mil-spec versions exist that also have additional  UV stabilizers  put in to survive long term in the sun- 

As a rule of thumb then unstabilised  PP or PE in full desert sun for about a year has lost 70% of flexibility and will show crazing and cracking right through if flexed

PVC loses its chlorine from the surface and slowly crazes with the damage stopping after a few mm, unless the cracks are opened by flexing to allow the UV deeper.This is over a couple of years of full desert sun exposure.

N on the other hand is dark so the UV does not penentrate and develops surface crazing due to loss of surface flexibility over about 5 times that period

It is worth knowing what you are selecting. All cables last better out of sunlight but in the UK most days are not desert sun levels of UV , and even the 'wrong' cables can last many decades if at least partly shaded.

Mike.

David Alcock said:

I believe it should be in scope of BS7671, as someone needs to certify it on install as compliant, and any cables used for Power should comply with BS or harmonised standards

BS 7671 doesn't agree, see Regulation 110.2 (xi), noting that cables and wiring systems are electrical equipment (see definition of electrical equipment in Part 2).

There is nothing to stop a designer, however, meeting the requirements of both BS EN 60204-1 and BS 7671, in cases where there are no conflicting requirements. And, to be clear, there are cases of conflict.

Which applies depends upon what you are doing, but why are the cables troubling you so much?

Home many machines are being installed, one or two please?

EG    H07RN-F

Indeed- but not say H05VV-F (which is ordinary 3183Y PVC flex) - that was my point.

   - Andy.

I dont believe there is one standard alone that you need to consider, its in some degree in my opinion that if you use just one i.e. manfacturers recommendation then it may fall fiul of other uk regulations or locations where you are installing the cable, so its engineering judgement, My judgement is it should be a power rated cable and type to suit the environment

For example, recently a contractor submitted data sheets for a cable that was not LSF in an environment that required it, and after its rejection another cable chosen was the same standard of cable but LSF whilst also being of the same standard to the manufacturers recommendations

H07RN-F not LSF to H07ZZ-F so for AC interconnector its power rated as supplies the indoor unit snd suutable for externsl use and LSF

David Alcock said:

I dont believe there is one standard alone that you need to consider, its in some degree in my opinion that if you use just one i.e. manfacturers recommendation then it may fall fiul of other uk regulations or locations where you are installing the cable, so its engineering judgement, My judgement is it should be a power rated cable and type to suit the environment

This is also true ... the installation of the cable is Construction Work as defined in CDM Regulations, and therefore, particularly for places of work, there are safety factors to consider.

However, some of the environmental and safety factors might include EMC ... so if the manufacturer recommends a cable like CY or SY for EMC purposes, then a suitable alternative arrangement of a wiring system is needed ... it could include, for example, cables in metallic conduit or trunking that provide an equivalent EMC performance. See also Section 444 of BS 7671, and BS IEC 61000-5-2.

Agree

Agree