Published: 31 October 2014
Category: Q&A
Jason asks this question, which concerns sleeving a flex cable’s earth core. He also wonders whether this practice is allowed. It has been answered by the NICEIC (Theme – Cables, Wiring and Wiring Accessories):
This Q & A is one of thousands posted in our Technical Expertise area, and answered on a daily basis by our Voltimum Experts.
Question: Is it permissible to sleeve the earth core to use as a switch wire in a three-core flex cable?
I have read that this practice is frowned upon - it is acceptable for flex cables only, but not for singles. Is this so?
Answer: This provision is used on a flex where the cross-sectional area of the conductor of the circuit protective conductor (CPC) is equal to the live conductors of the flex.
However, the flex must be over-sleeved at its terminations, and consideration as to whether the cable requires a CPC for compliance with BS 7671 must be adhered to.
It is frowned upon as, ideally, a four-core flex should be used in the first instance to resolve the issue.
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