I was approached by a builder today and he has asked me if he can run heavy guage pvc conduit(with neoprane gaskets to all the 'T' /thru /end boxes) buried in a trench with all the usual soil/hardcore/danger tape on top in excess of 500mm to supply 3 garden lights).......any comments?
Just checked the regs and regulation 522-06-03 may have answered my query,still any other comments are welcome.
Hi sparky sifi The builder is perfectly okay in what he is suggesting. What he may need help with is cable sizing and conduit sizing. If the garden lights are an appreciable distance down the garden (40-50m say) consider 2.5mm2 T&E cable (you may get away with less if you know how to do voltage drop calcs). This will also have the benefit of coping with "add-on" lighting in the future without worrying about the cable size as once its all in and buried it is going to be a real pain to dig it up and change it! The conduit I would recommend is 32mm dia. as 25mm dia. will be too tight to pull the cables. You may like to suggest blck conduit if it is emerging from the ground anywhere as this is less unsightly than white and more resistant to UV from the sun. Apart from this good luck.. RSS
I think he was suggesting using singles in 20mm me thinks?with separate cpc of course,i was wondering about 1.5mm considering the depth he is proposing which should hopefully eliminate penetration with all that soil and concrete on top,also it would be easier to draw the cables through. All the conduit I think I am right in saying will be unseen from human eyes so uv shouldnt be a prob.
I have had a look at 1.5's and this is what I think... Going by the on site guide with regard to voltage drop,1.5's would give on a run length of 40M with 5 lamps running max 100W (realisticly he reckons he will use 60W) 29240/1000=2.32v 29-voltage drop in mV for 1.5 2 Ib 1000 converts mV to V 40-run length Could someone else also check theese calcs,just in case I missed something.
Hi again Agree with the calcs. Would suggest using 6242Y though instead of singles as the pvc sheath will give that extra protection to the wires underground in the conduit...also agree that if using only a single cable 20mm conduit should be okay. RSS