i have a 10.5 kw showerand need to run a cable some 25 meters one electrician says 10 mm Twin & earth will suffice but others say it should be 16mm. i am led to believe that 10mm goes up to 9.5kw. any advice would be welcome
Did it say why?Big_Spark said:Not sure of when the non-compliance kicks in, but manually calculating at 25 m and using my cbale calc software the cable must be 16mm² for compliance.
It shouldn't be hard to establish that it isn't that....smokeyJoe said:Which rule(s) are we using to determine compliance here?
voltage drop (525-01-02)?
Those two are effectively the same, and assuming TN-S & B50 was how I got to 22.1mdisconnection time assuming a TN system (413-02-08)?
impedance of the protective conductor to the main equipotential bond with a guess at the type of protective device (413-02-13)?
ban-all-sheds said:Can't remember the figure for TN-C-S but it was a lot more....
ban-all-sheds said:XLPE SWA is only rated as high as it is because the insulation can tolerate higher temperatures.
Run conductors at 90°C into normal switches and shower terminal blocks and expect trouble....
That's what I said. I can't remember how much higher, and I can't be **sed to work it out again. I have a vague memory that volt-drop kicked in at a lower figure anyway.securespark said:ban-all-sheds said:Can't remember the figure for TN-C-S but it was a lot more....
Mmmmm. PME has Ze of 0.35Ohm. It will be much higher.
Big_Spark said:BAS..the reason SWA XLPE or PVC/PVC has a higher current rating is actually due to the copper the cable is made from.
T&E is soft drawn annealed copper that is only 98% pure for compliance with the relevent BS, however SWA XLPE or PVC/PVC is hard-drawn annealed and 99.1% pure as a minimum..typically most seem to be about 99.4% pure copper..
The annealing process has an effect on the current carrying capacity of the cable, the insulation has a minor effect, but not to the extent that exists...
Meaningless.I do agree with the 90°C comment however..but if you ever find that in your home I think you'll already be dead..
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