= Electric power distribution
<Electric power distribution> is the part of an <electric power system> that delivers electrical <energy> from supply points to connected <electrical loads>. It uses conductors, switching and protective equipment, and often <electrical transformers> to provide suitable local <electric potential differences>. <Electric power transmission> mainly transfers bulk <power> between supply regions and major receiving points; the distinction concerns network function rather than one universal voltage threshold.
A one-line diagram suppresses individual phase conductors to show the supply-to-load structure. The DOE handbook's apparatus example connects utility and standby supplies, buses, switching and protection to the consuming circuits.<DOE Fundamentals Handbook Electrical Science>[Volume 4, Module 15, System Components and Protection Devices, printed pp.1–6, Figure 1]{ref} Following the actual connection points is necessary before assigning losses or assuming that two loads share a return path.
For an original two-wire <direct current> example, a source holds $V_s=240\,\mathrm V$ and supplies a resistive <electrical load> $R_L=12\,\Omega$ through an outgoing-plus-return conductor <electrical resistance> $R_w=0.4\,\Omega$. <Ohm's law> gives
$$
I=\frac{240}{12.4}\,\mathrm A\approx19.355\,\mathrm A,
\qquad V_L=IR_L\approx232.258\,\mathrm V.
$$
The conductor heating is $I^2R_w\approx149.84\,\mathrm W$, while the load receives $I^2R_L\approx4.4953\,\mathrm{kW}$. Their sum equals the source output $V_sI\approx4.6452\,\mathrm{kW}$. Assigning the full source <electric potential difference> to the load would miss both its reduced terminal value and the location of the dissipated <energy>.
A proposed bench demonstration uses a current-limited low-voltage supply, a known series <resistor> representing the wires and a separate load <resistor>. Simultaneously measuring source and load <electric potential differences> and branch <electric current> tests the loss calculation. Real <alternating current> networks add <electrical reactance>, phase imbalance and protection constraints; the simple example isolates conductor heating rather than representing every distribution effect.
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