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Once you decide how much load capacity you require , the rest is simple using the voltage drop calculation and the tabulated values in the OSG
Discuss Cable Size for 100m Shed Run in the UK Electrical Forum area at ElectriciansForums.net
please could you in light use how you got to this equation .If looking at, say, 10A max load and a 16A B-curve MCB then Zs max is 2.2 ohm, assuming TN-S max of 0.8 ohm then 1.4 ohm for R1+R2 or 14mOhm/m for a 100m cable run.
Looking at the 2-core SWA for mucho cheapness, then
So either those should be fine. Assuming 16A B-curve MCB/RCBO of course!
- 6mm is 3.1+7 = 10.1 mOhm/m
- 4mm is 4.6+7.9 = 12.4mOhm/m
Also assuming the SWA is properly glanded to get a good and reliable connection to the armour!
Starting point was the light load, so assume enough for a 13A socket and not much more. So Table B6 of the OSG has Zs limit at 2.2 ohms for 16A B-curve MCB.please could you in light use how you got to this equation .
Can anyone recommend a good Cable Size calculator to use online?
The old man wants me to order some 6mm 3 SWA to feed his shed that will go on to supply some sockets, fairy lights around the garden and other stuff, no power tools or high load activities.
Cost is the mitigating factor here because the cable run is (his estimate) 100m (my estimate is 70 meters) from Consumer unit to shed running through the full length of his bungalow attic, down one side of the house and that ran along the kick board or bottom of his fence around the side of his garden.
Im thinking it might have to be 10mm which is going to put the job past his budget.
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