T&E is not really suitable for the outside environment due to it have low mechanical protection vaules
E.g impact, vermean
Which are all really important when installing a cable in any location. Selection of the right install method and cable is so important
Look at reg 544.1.2 pg164
Main protective bonding must be carried out if not installed as it keeps all live parts at the same potenial if a fault was to occur reducing the risk to humans