Amendments Made to BS 8436

Dr. Jeremy Hodge, Chief Executive at the British Approvals Service for Cables (BASEC) comments on the recent amendments made to BS 8436.

Cable specified in BS 8436 is increasingly being used at shallow depths in partitioning and related applications, in accordance with the IET Wiring Regulations BS 7671.  The special construction of these cables allows circuit protection devices to operate quickly.

However, the British Standards Institution (BSI) is wisely being cautious in its recent amendments to BS 8436.

Addressing a need

When the standard was first introduced, BS 8436 cables were restricted to domestic and light uses – shallow depth partitions, stud walls etc. and have a normal 300/500V voltage rating. However, due to this cable’s possible electromagnetic interference screening properties, it is being used in more industrial applications such as hospitals where electrical interference causes concern. As a result, larger sizes and higher voltage ratings are being increasingly specified. However, this was not the use anticipated when the standard was first established and there is no ‘larger’ option available with these particular screening properties.

The amendment has gone some way to addressing this situation by increasing the maximum nominal size to 4mm², which will now cover some domestic uses such as radial circuits. However it will still not address the need for larger sized domestic applications such as showers and cookers. In BASEC’s view more work needs to be done to extend the reliable testing range for these British standard cables, including the important nail penetration test, in order to fully justify larger sizes.

An Irish standard for similar cables does provide for larger sizes and a higher voltage rating, but these would be outside the intended scope set out in BS 7671. Some cable manufacturers make these cables compliant with both the British and the Irish standards, and this can cause confusion for purchasers, particularly as the marking requirements would include two voltage ratings. This opens a debate as to whether cables should be marked as complying with more than one standard.

Further information about BASEC is available at or you can contact BASEC directly at or +44 1908 267300

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