Considering the following formulas for voltage drop, what additional factors need to be included and how can resistance be derived to thoroughly calculate theoretical voltage drop for multiple scenarios?

For example, cables run in steel conduit will need to be treated differently than cables run in 'free space' (this falls under resistance but is additional to cable resistance). The National Electric Code contains resistance & impedance data but only for specific scenarios and cable ratings.

How can one cover all necessary factors in the absence of raw data in order to produce an accurate result? Or, how can one obtain the data if it exists?

  1. DC: Vd = \$2IRL\$

  2. Single phase: Vd = \$2IZL\$

  3. Three phase: Vd = \$\sqrt{3}ZL\$

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    \$\begingroup\$ Please feel free to correct the formatting of the formulas. \$\endgroup\$ – Lott99 Jul 1 at 22:50

Two additional factors that should be considered are the power factor of the load and the L/R for the cable. The effect of steel conduit is related to cable inductance. The major electrical equipment manufacturers such as ABB, Allen-Bradley, Eaton, Schneider Electric and Siemens may have helpful information. There are online voltage drop calculators. Some major electric utilities may have information. There may be handbooks published by IEEE or others. NFPA's guide to the NEC may have something.

For 50 for 60 Hz, frequency should not be an issue, but it might be for 400 Hz and would certainly be for higher frequency.

I use the following:

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