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The use of SY cable in Lift installations

David Alcock

Hi,

I've noticed recently that lift companies tend to use SY cable for the supply cable from the Mian isolator (provided by main MEP contractor  under BS7671) to the lift control panel main intake connection of the lift

I know Lifts are not covered by BS7671, but I'm aware that these cable types are designed for use in Control environments and are discouraged in BS7671 for power circuits/Fixed installations

when questioned lift companies just issue data sheets for the said cable, spouting VDE compliance, although they are not manufactured to any manufacturing standard, how do they certify the installation when every way you look points to them not to be used as power cables? even if in lift installations? 

:The cable manufacturers even state on their data sheet they are "control cables" with mech protection 

Regards

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  • mapj1 said:
    The copper cores are of course made to a standard, just not one invented here, and knowledge of the stranding and copper purity from that allows those skilled in the art to deduce a resistance and a voltage drop- tables in OSG or '7671 are for those who can't, but those who can, are allowed to.

    The copper cores are usually quoted to BS EN 60228,  which is the same standard used in most, if not all, cables used in BS 7671.

    The actual issue with CY/SY/YY cables is the fact that other elements of the cable construction are NOT documented in a cable constructional standard (in the UK or in the DIN/VDE standard often quoted for these cable types). The constructional standard determines insulation type and thickness, layup, and sheathing type, and, for CY and SY types, % coverage of the copper (CY) or steel (SY) screen. The actual construction affects voltage drop as well as current-carrying capacity, and effectiveness of the screen for EMC purposes.

    The IET On-Site Guide provides guidance on what to check for when deciding to use CY/SY/YY cables (see Section 7.9, page 100, of the 2022 version).



    A final issue, is to make sure you get the right kind of CY/SY/YY cable ... some are only suitable for use as auxiliary cables and these are not suitable for power supplies/power circuits.

Reply
  • mapj1 said:
    The copper cores are of course made to a standard, just not one invented here, and knowledge of the stranding and copper purity from that allows those skilled in the art to deduce a resistance and a voltage drop- tables in OSG or '7671 are for those who can't, but those who can, are allowed to.

    The copper cores are usually quoted to BS EN 60228,  which is the same standard used in most, if not all, cables used in BS 7671.

    The actual issue with CY/SY/YY cables is the fact that other elements of the cable construction are NOT documented in a cable constructional standard (in the UK or in the DIN/VDE standard often quoted for these cable types). The constructional standard determines insulation type and thickness, layup, and sheathing type, and, for CY and SY types, % coverage of the copper (CY) or steel (SY) screen. The actual construction affects voltage drop as well as current-carrying capacity, and effectiveness of the screen for EMC purposes.

    The IET On-Site Guide provides guidance on what to check for when deciding to use CY/SY/YY cables (see Section 7.9, page 100, of the 2022 version).



    A final issue, is to make sure you get the right kind of CY/SY/YY cable ... some are only suitable for use as auxiliary cables and these are not suitable for power supplies/power circuits.

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