I think that's more of a suggestion than a requirement, and even then it's meant more for chippies who seem to think it's ok to go around sawing through cables and having to "wiggle the lead" is just one of those things you have to do sometimes.
It is a suggestion from the IEE however if it went to court during an investigation the Health and Safety at Work Act would be used.
For example how can you prove the plant was in operation condition for its correct use, the only valid way would be to follow the suggestion from the IEE.
Remember prior to BS7671 the Wiring Regs wasn't a legal requirement, think it was the early 90's they became a BS.
I reckon my defence would be that I'm qualified to inspect & test my own gear so I would know what to look out for in terms of damage, ie it is visually inspected before, during and after use.
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