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SY Cabling - Current Carrying Capacity

ElectricalCuriousity

Often I am finding SY used for the permanent fixed wiring of installations for circuits like Air Conditioning and Sockets. Apart from the obvious with SY Cable not permitted as such for these circuits as per BS 7671, Is there a specific current carrying capacity table for SY? This is because sometimes on EICR's we are finding SY being too small for the load but cannot always find the exact table/document to back this up.

Thanks

ElectricalCuriousity

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    In my view, the braid of SY cable should be earthed under all common conditions, but should not be relied upon as the sole means of earthing. One core should be used as the earth IN ADDITION to the braid.

    The braid needs earthing as it could become live in cases of damage. The braid should not be relied upon as the sole means of earthing as the conductivity is too low.

    Returning to current carrying capacity, I would expect that SY would have a greater current carrying capacity than a similar sized PVC insulated and sheathed flexible cord, due to the greater diameter and surface area from which heat can be dissipated. However in the absence of any PROOF of this higher rating, I would adopt a cautious approach and assume the same rating as PVC flex. 

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  • 0

    In my view, the braid of SY cable should be earthed under all common conditions, but should not be relied upon as the sole means of earthing. One core should be used as the earth IN ADDITION to the braid.

    The braid needs earthing as it could become live in cases of damage. The braid should not be relied upon as the sole means of earthing as the conductivity is too low.

    Returning to current carrying capacity, I would expect that SY would have a greater current carrying capacity than a similar sized PVC insulated and sheathed flexible cord, due to the greater diameter and surface area from which heat can be dissipated. However in the absence of any PROOF of this higher rating, I would adopt a cautious approach and assume the same rating as PVC flex. 

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