if it’s supplies and labour get your sparky to purchase conduit. If he purchases an excessive amount of he can maintain the excess.I have fed 1000s of 2 x 2.5mm T&E drops down 20mm oval conduit drops, without the need of resorting to any lubricant, but only at any time with picked helps make of cable and conduit. Prysman and M/Tuflex recently.ENM