Electrical Circuits
Voltage Drop
Voltage drop is the loss of voltage along the conductors that carry a load current. In a two-wire circuit the current travels out through one conductor and back through the other, so the total drop is twice the drop of a single conductor. Excessive voltage drop starves the load and converts energy into heat in the wiring, which is why conductor size and run length matter.
Voltage Drop
V_drop = 2 × I × R_conductor
Variables and units
| Symbol | Quantity | Unit |
|---|---|---|
| V_drop | Total voltage drop in the loop | V |
| I | Load current | A |
| R_conductor | Resistance of one conductor | Ω |
Conditions of application
Two-wire circuit with equal go and return conductor resistance. Add connection and protective-device resistance separately; for three-phase circuits the relationship differs.
Worked example
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