For 6mm2 T&E, I might likely use independent 20mm oval conduits, just one for every of The 2 cables, but I would guess you would have to have 32mm oval conduit it you actually wanted to put each in a single length. Onsite availability differs by region and repair ordered. https://round-conduit80012.shotblogs.com/examine-this-report-on-round-conduit-41502182