What reference method?

[Rockingit]

Got an install that doesn't quite fit any of the tabled methods... more than 3 SWA's laid in 6 x 6 galv conduit, inset in screed / concrete, with lid. Ref 70 applies to ground (soil) and 118/119/120 is direct to concrete which has different thermal propogation than the galv that they're actually sat on.

Suggestions on a postcard to.....

 

[DefyG]

Ref D (70) ........ '..... or in ducting in ground' Not specific what the ducting or ground is made from!
or
Ref B (44/46/51) ...... ? Again not specific of ducting material!