[Citroënbender]

You’re thinking of direct burial XLPE?

I’ve already got orange conduit buried under concrete between house and shed, 32mm dia x 600 deep, draw cord all ready, no warning tape though. It turns up to a weatherproof junction box mounted to the house wall at floor level.

If I re-mount the junction box 150mm lower, I can use 25mm HD corrugated conduit with a gland, entering at the rear of the box and punching straight through the wall just under the joist. Conduit under the house can mostly be run quite readily - just a few single skin sub walls to bore through.