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Temperature rating of C.B's, cables and conduits

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Question 1: All PVC conduits in market to BS:61386 are rated for 60C operating temp while CU/PVC single core wires to IEC 60228 are rated for 70C. what is the BS 7671 point of view.
Question 2: BS 7671 section 512.1.5 states that :Switchgear, protective devices, accessories and other types of equipment shall not be connected to conductors

intended to operate at a temperature exceeding 70°C at the equipment in normal service unless the equipment manufacturer has confirmed that the equipment is suitable for such conditions, or the conductor size shall be chosen based on the current ratings for 70° C cables of a similar construction. where as NEC 110.14(c): “Conductors with temperature ratings higher than specified for terminations shall be permitted to be used for ampacity adjustment,correction, or both.” Derating factors may be required because of the number of conductors in a conduit, higher ambient temperatures, or internal design requirements for a facility. By beginning the derating process at the ampacity of the conductor based on the higher insulation value, you may not be required to upsize the conductor to compensate for the derating.is there a similar way to apply the exception of NEC using the BS 7671.
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    MOESEB:

     CU/PVC single core wires to IEC 60228 are rated for 70C. 




    IEC 60228 is the standard for the 'Conductors of insulated cables', so only deals with the copper (or aluminium), not the insulation, and therefore does not have a temperature rating. You will need to check what standard covers the insulation of the PVC. I know the Americans have what they call 'High Temperature PVC' which they allow to operate at 105°C, though I can't remember seeing that accepted elsewhere.

    The temperature rating assigned generally dictates the testing requirements so in theory as cable tested as suitable for 70°C should be able to operate at that temperature (though the more I find out about the testing regime the less confidence I have in the tests definitively proving suitability anyway, but that is a different story).

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  • 0

    MOESEB:

     CU/PVC single core wires to IEC 60228 are rated for 70C. 




    IEC 60228 is the standard for the 'Conductors of insulated cables', so only deals with the copper (or aluminium), not the insulation, and therefore does not have a temperature rating. You will need to check what standard covers the insulation of the PVC. I know the Americans have what they call 'High Temperature PVC' which they allow to operate at 105°C, though I can't remember seeing that accepted elsewhere.

    The temperature rating assigned generally dictates the testing requirements so in theory as cable tested as suitable for 70°C should be able to operate at that temperature (though the more I find out about the testing regime the less confidence I have in the tests definitively proving suitability anyway, but that is a different story).

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