Sharpend
"It Just Is"
Now that is how to answer a post, well done slips. No more to be said really!Cut to the chase here. It should be TT'ed at the container so only a 2 core is needed saving you some money. The armouring should be earthed at the supply end & isolated at the container end. You should also have it protected by a Rcd and i would fit that in the container but be aware of the rules regarding metal enclosures and TT systems.