Cable Length in Calcs

Postby ml09616 » Sun Mar 22, 2009 11:40 pm

When calculating the cable size required for a particular circuit, is the length of the cable run (in the formula), the length from the CU to the point of service only, or is it double this length, ie from the CU to the service point, then back to the CU again?
ie size = (1.72 x 10^-2 x cable length (m) / R ( cable resistance)

regards all...
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Postby kbrownie » Mon Mar 23, 2009 4:59 pm

Cable length in voltage drop calc.
Cable size is calc using ib, in and de-rating using route, thermal insulation, grouping factors, bs3036 fuse, ambient temp to workout (it) then findind the cable csa most suitable to carry that current, after that you calc volt drop using length the cable runs. ie if your last light on a circuit was 25 meters away calc using 25 m
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Postby sparx » Tue Mar 24, 2009 8:49 pm

Hi, KB's last line says it, ie tables refer to distance of CABLE to end of circuit not CORE,
regards SPARX
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Postby ml09616 » Tue Mar 24, 2009 9:29 pm

Thanks for the replies folks....
you have been most helpful and it is greatly appreciated.

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Joined: Sun Mar 22, 2009 11:34 pm

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