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The cross-sectional area of neutral is
Double than line conductor
Quarter than line conductor
Half of the line conductor
None of these
Half of the line conductor
In a balanced three-phase distribution system, the neutral wire typically carries little to no current. Therefore, for economic reasons, it is standard practice to design the neutral conductor with a cross-sectional area equal to half (or sometimes even less) of the phase (line) conductor.
In a balanced three-phase distribution system, the neutral wire typically carries little to no current. Therefore, for economic reasons, it is standard practice to design the neutral conductor with a cross-sectional area equal to half (or sometimes even less) of the phase (line) conductor.
InтАЛ=IaтАЛ+IbтАЛ+IcтАЛ тАФ Neutral current calculation
AnтАЛ=21тАЛApтАЛ тАФ Standard sizing rule for neutral conductor
The current in the neutral conductor (InтАЛ) is the vector sum of the individual phase currents (IaтАЛ,IbтАЛ,IcтАЛ). In a perfectly balanced load condition, InтАЛ=0. While practical distribution systems are often unbalanced, the neutral current remains significantly lower than the individual phase currents, allowing for a smaller conductor size to reduce material costs.
Neutral wire sizing is dictated by the expected unbalanced current, not the full load current.
Cost optimization is a major driver in distribution system design.
Safety regulations (like IS codes) may mandate a minimum cross-section for mechanical strength despite low current requirements.
Significant reduction in material cost (copper or aluminum)
Lower overall weight on the distribution poles
Potential for overheating if the system becomes severely unbalanced
May require extra mechanical reinforcement in long spans
Low-voltage (LV) distribution networks
Service lines to residential consumers
In systems where non-linear loads (like LEDs or computer power supplies) create significant third-harmonic currents, the neutral current may actually exceed the phase current, necessitating a full-sized or oversized neutral.
Option A is incorrect because double the area would be an uneconomical waste of material.
C is correct тАФ The cross-sectional area of the neutral conductor is typically designed to be half of the line conductor to optimize material costs in balanced distribution systems.
Always remember that while the neutral is 'half-sized' for cost, modern power systems with heavy harmonics may require the neutral to be sized differently to prevent thermal damage.