Personal tools

Sizing and protection of conductors

From Electrical Installation Guide

Jump to: navigation , search
General rules of electrical installation design
Connection to the MV utility distribution network
Connection to the LV utility distribution network
MV and LV architecture selection guide
LV Distribution
Protection against electric shocks
Sizing and protection of conductors
LV switchgear: functions and selection
Overvoltage protection
Energy Efficiency in electrical distribution
Power Factor Correction
Power harmonics management
Characteristics of particular sources and loads
PhotoVoltaic (PV) installation
Residential and other special locations
ElectroMagnetic Compatibility (EMC)

Conductor sizing and protection

Methodology and definition

Overcurrent protection principles

Practical values for a protective scheme

Location of protective devices

Conductors in parallel

Practical method for determining the smallest allowable cross-sectional area of circuit conductors

General method for cable sizing

Recommended simplified approach for cable sizing

Busbar trunking systems

Determination of voltage drop

Maximum voltage drop limit

Calculation of voltage drop in steady load conditions

Short-circuit current

Short-circuit current at the secondary terminals of a MV/LV distribution transformer

3-phase short-circuit current (Isc) at any point within a LV installation

Isc at the receiving end of a feeder as a function of the Isc at its sending end

Short-circuit current supplied by an alternator or an inverter: refer to Characteristics of particular sources and loads

Particular cases of short-circuit current

Calculation of minimum levels of short-circuit current

Verification of the withstand capabilities of cables under short-circuit conditions

Protective earthing conductor

Connection and choice for protective earthing conductor

Sizing of protective earthing conductor

Protective conductor between MV/LV transformer and the main general distribution board (MGDB)

Equipotential conductor

The neutral conductor

Sizing the neutral conductor

Protection of the neutral conductor

Breaking of the neutral conductor

Isolation of the neutral conductor

Worked example of cable calculation


External links