I am sizing cables to NEC for an LNG Facility in Peru, following the rules from Article 310 of NFPA 70. The cables must be direct buried. From the main 13.8kV Switchboard there are 28 feeders to transformers (14 from bus A and 14 from bus B). Here, the probelm arises. From NEC Figure 310.60, it...
My cable sizing calculations (to NEC standards) have told me that I need 4 x triplexed circuits in one trench for a particular situation. For ease of installation it would be desirable to have 3 'groups such that the arrangement has the 4 'reds' grouped together, likewise with the other two...
I am sizing MV/HV cables for direct burial based on NEC Standards. It does not seem to mention in detail within article 310 of NFPA 70, the ampacity adjustment factors for changes in temperature, thermal soil resistivity and grouping from the 'base' values. What I have done thus far is take the...
