What is the cross-sectional area (CSA) of consumer tails?

The correct answer for the cross-sectional area (CSA) of consumer tails is indeed 25 mm². In the context of electrical installation and regulations, consumer tails are the conductors that connect the supply authority's service line to the consumer's distribution board. The cross-sectional area is significant because it relates to the current-carrying capacity of the cables and ensures that they can handle the expected load safely without overheating.

For residential applications, the minimum CSA for consumer tails is often specified in regulations to ensure that the installation is safe and meets performance standards. A value of 25 mm² is commonly accepted in many guidelines, allowing it to accommodate typical residential load requirements while providing a degree of safety against overcurrent conditions.

The other options represent common sizes that may be used in various electrical applications, but they do not meet the minimum requirements for consumer tails as per the standard recommendations usually adopted in building regulations.