Chapter G

Sizing and protection of conductors


Determination of voltage drop

From Electrical Installation Guide
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The impedance of circuit conductors is low but not negligible: when carrying load current there is a voltage drop between the origin of the circuit and the load terminals. The correct operation of a load (a motor, lighting circuit, etc.) depends on the voltage at its terminals being maintained at a value close to its rated value. It is necessary therefore to determine the circuit conductors such that at full-load current, the load terminal voltage is maintained within the limits required for correct performance.

This section deals with methods of determining voltage drops, in order to check that:

  • They comply with the particular standards and regulations in force
  • They can be tolerated by the load
  • They satisfy the essential operational requirements
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