Grounding Conductors

[Mike01]

when sizing grounding conductors for xfmr secondary conductors you size per nec 250.66, when you have mulitple sets of conductors you add the sum of the conductors, according to the 2005nec article 250.24(c).1 it indicates how to route and size, for conductors over 1100kcmil(copper) shall not have an ampacity of less than 12.5% of the largest service entrance phase conductor.


so for a 3000 amp service served with 8 sets of 600kcmil per phase is the following correct?

600*8 = 3250kcmil total per phase = 4800000 *.12.5% = 600000


so does this mean that the ground conductor shall be a 600kcmil per phase or is a 3/0 sufficent per the chart of 250.66??

 

[infinity]

Look at 250.102(C).

 

[George Stolz]

Discussion continued here.