I know the subject of SY cables in fixed power installations pops up a lot but please bear with me.
I know that SY cable does not meet any British or harmonised standards and is 'discouraged' under BS 7671, but can be installed and noted as a departure on the installation certificate.
As it will need to be 'safe' under BS 7671, should SY cable be installed in metallic containment such as steel trunking?
It seems to me that SY is being considered "the same as" flexible SWA. This is not true as the braid is mechanical protection only and is not suitable as the CPC. SY cables with mains colour cores have a G/Y core too, it is those that are aimed at LV control functions that may not. Therefore the resistance of the hard steel braid is not a consideration, and it is likely that a penetrating nail will simply burn up the surrounding braid, It does provide considerable extra protection from knocks and sharp objects etc. compared to soft sheathed cable
This is not true as the braid is mechanical protection only and is not suitable as the CPC.
That is not true ... the braid of SY is mainly for screen, for EMC purposes, and offers little or no mechanical protection, certainly in comparison to the armour of a cable. If there is a sheath beneath the braid, it may offer some additional protection to that sheath, in terms of protection against scuffing or cutting, of a fashion, but not penetration as with armour ... but I guess that is why we could do with a proper constructional standard for these cables.
SY cables with mains colour cores have a G/Y core too,
SY cables with black cores adopting numeric core identification also have GNYE core (Note GNYE is the correct abbreviation, see Amendment 2 - but this is not new, the two-letter colour code, with 4 letters used for bi-colour, was originally harmonized many years ago, and was published shortly after harmonization as BS 7645:1993 !).
For information, 2 core power cables are available without GNYE cpc ... and auxiliary (control) cables can be purchased that have a GNYE cpc ... perhaps because, as well as the fact that LV could be used for controls, PELV is preferred in Machinery (as defined), and the cpc would be run between all points.
Therefore the resistance of the hard steel braid is not a consideration, and it is likely that a penetrating nail will simply burn up the surrounding braid, It does provide considerable extra protection from knocks and sharp objects etc. compared to soft sheathed cable
Not true, and it is not the function of the braid. It is only the fact that the cable is sheathed, which prevents the braid from having to be a protective conductor ... and perhaps that's another discussion point as to why the guidance on BS 7671 advises caution, regards accidental penetration of the cable in certain environments.
This is not true as the braid is mechanical protection only and is not suitable as the CPC.
That is not true ... the braid of SY is mainly for screen, for EMC purposes, and offers little or no mechanical protection, certainly in comparison to the armour of a cable. If there is a sheath beneath the braid, it may offer some additional protection to that sheath, in terms of protection against scuffing or cutting, of a fashion, but not penetration as with armour ... but I guess that is why we could do with a proper constructional standard for these cables.
SY cables with mains colour cores have a G/Y core too,
SY cables with black cores adopting numeric core identification also have GNYE core (Note GNYE is the correct abbreviation, see Amendment 2 - but this is not new, the two-letter colour code, with 4 letters used for bi-colour, was originally harmonized many years ago, and was published shortly after harmonization as BS 7645:1993 !).
For information, 2 core power cables are available without GNYE cpc ... and auxiliary (control) cables can be purchased that have a GNYE cpc ... perhaps because, as well as the fact that LV could be used for controls, PELV is preferred in Machinery (as defined), and the cpc would be run between all points.
Therefore the resistance of the hard steel braid is not a consideration, and it is likely that a penetrating nail will simply burn up the surrounding braid, It does provide considerable extra protection from knocks and sharp objects etc. compared to soft sheathed cable
Not true, and it is not the function of the braid. It is only the fact that the cable is sheathed, which prevents the braid from having to be a protective conductor ... and perhaps that's another discussion point as to why the guidance on BS 7671 advises caution, regards accidental penetration of the cable in certain environments.
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