OK the cable is made to DIN 57250 VDE 0250-1.
It is an acceptable wiring material for use in Germany.
Germany use EN 60364 for their wiring standard.
BS7671 is the UK implementation of EN 60364.
Ergo, it is acceptable, as long as it's treated correctly.
It has a class 5 stranded conductor according to IEC 60228.
The insulation is PVC, with a PVC bedding, the overbraid & a PVC sheath.
The braid is braid, not armour.
If it is treated like BS6500 flex, then it's fine, so use the current carrying capacity for BS6500 flex, and installation methods in accordance with BS6500 flex, gland it correctly, earth the braid supply end.
OK, yes I know BS6500 has now been withdrawn, and replaced by EN 50525, but 6500 is easier to type!
Now you will find CY, CY & YY cable being approved to EN50525.
See here:
http://www.clevelandcable.com/products/standards/bs-en-50525211-cable/sy-control-cable-sy-control-flex-bs-en-50525211-and-vde-0250/
As this is a harmonised standard under the LVD, it means one cable for the whole of the EU market, hence the movement by cable manufacturers over to "certifying" their cables to the EN std.
Remember we are still in a state of flux over cable standards as they are only now being harmonised, as a result of the Construction Products Directive.
I will use it, and have used it, but, for specific properties that other cables would not posses, e.g. the class 5 conductor, which is more resistant to vibration.
If you have external influence AH2 or AH3 then a class 5 conductor is more suitable, thus, SWA, 6491x 6004 type cables tend to be unsuitable.
They tend to be class 1 or 2 conductors.
OK, yes you could then say that a 6500 flex has a class 5 conductor, which it may, but, with SY you have an additional layer of the braid and the outer sheath as extra mechanical protection.
Remember that the sheath on a flex to 6500 is not insulation it's a sheath, simply offering mechanical protection for the insulation over the conductors.
Thus the answer to the question, is, if it is selected & installed correctly and complies with EN50525-2-11, then it's fine to use under BS7671.
