Morning, I have some boulard lamps in my garden. Want to connect them together using 16amp cabtyre in a condude feeding from a sub-db outside the pool building.which has a earth-leakage already installed and will go via a trip switch (LED globes will be used) 10 x 12Watt LED globes and will be using ferrules on the ends of cabtyre to go into connector blocks . ANY LEGAL ISSUES HERE ??

Apologies, this reply is a bit late, I'm guessing you may have already finished your installation.

Cabtyre (I assume standard PVC and not HO5/HO7) is not great as an installation cable. It's not rated for below ground use, it's often not UV stable and as you pointed out it's fine stranded conductors so you need to ferrule the wires before any types of termination and it's also relatively expensive compared to flat twin + earth. Cabtyre current ratings are usually for trailing in free-air and often they won't give a current rating for different installation methods like in conduit because its not really meant to be used that way.

That doesn't mean it contradictory to the regs however, in recent years SANS10142 has become more tolerant of this kind of cable being used in installations as long as the manufacturers instructions allows it.

Just for future planning, it would be a lot cheaper and probably easier to use 1,0mm flat twin +e cable in conduit from a 6A or 10A circuit breaker. That would have been more than sufficient for the circuit you were installing which had a running current requirement of maybe 0.5-1 Amp.