NECA Technical receive many enquiries regarding mechanical protection of cables, with many believing any cable below 2.4 metres requires additional mechanical protection. This is not the case and there is no rule requiring it.
The following Wiring Rules clause identifies the requirements for mechanical protection:
Effectively, consideration is given to the environment the cables are to be installed in and what is likely to occur. If the cable is not likely to be subject to any damage, then no additional protection is required.