You can now size DC cables to NEC standards!
Simply select “DC” in the number of phases selection box:
And size the cable as normal. Obviously, the full load power factor will be ignored in the load calculations. Another change is the inclusion of conductor operating temperature in the voltage drop calculation:
This has been done to account for the temperature dependency of the DC resistance, which can lead to higher resistances at high conductor operating temperatures. The voltage drop is therefore calculated as follows:
- I is the DC load current (A)
- Rc is the DC resistance of the cable at 68°F (Ohms / 1000ft)
- L is the cable length (ft)
- T is the conductor operating temperature (°F)
- α is the temperature coefficient of resistance, which is 0.00218333 Ω/°F for copper and 0.00227778 Ω/°F for aluminum.