Schneider Electric - Electrical installation guide 2009
G
© Schneider Electric - all rights reserved
Chapter G
Sizing and protection of conductors
Contents
General
G2
1.1 Methodology and definition
G2
1.2 Overcurrent protection principles
G4
1.3 Practical values for a protective scheme
G4
1.4 Location of protective devices
G6
1.5 Conductors in parallel
G6
Practical method for determining the smallest allowable
G7
cross-sectional area of circuit conductors
2.1 General
G7
2.2 General method for cables
G7
2.3 Recommended simplified approach for cables
G16
2.4 Busbar trunking systems
G18
Determination of voltage drop
G20
3.1 Maximum voltage drop limit
G20
3.2 Calculation of voltage drop in steady load conditions
G21
Short-circuit current
G24
4.1 Short-circuit current at the secondary terminals of
G24
a MV/LV distribution transformer
4.2 3-phase short-circuit current (Isc) at any point within
G25
a LV installation
4.3 Isc at the receiving end of a feeder in terms of the Isc
G28
at its sending end
4.4 Short-circuit current supplied by an alternator or an inverter
G29
Particular cases of short-circuit current
G30
5.1 Calculation of minimum levels of short-circuit current
G30
5.2 Verification of the withstand capabilities of cables under
G35
short-circuit conditions
Protective earthing conductor
G37
6.1 Connection and choice
G37
6.2 Conductor sizing
G38
6.3 Protective conductor between MV/LV transformer and
G40
the main general distribution board (MGDB)
6.4 Equipotential conductor
G41
The neutral conductor
G42
7.1 Sizing the neutral conductor
G42
7.2 Protection of the neutral conductor
G42
7.3 Breaking of the neutral conductor
G44
7.4 Isolation of the neutral conductor
G44
Worked example of cable calculation
G46
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Schneider Electric - Electrical installation guide 2009
G - Sizing and protection of conductors
G2
© Schneider Electric - all