More about Electrical Building Services

High Voltage

In buildings with high power demand it is normal for the electrical power to be supplied at High Voltage or 11,000 Volts. As electrical power is normally used at Low Voltage a transformer is required to convert the voltage for use in the building.


A transformer converts the electrical power supplied at High Voltage into Low Voltage for use by the electrical equipment within the building.

Low Voltage

Smaller buildings and buildings with lower power requirements are supplied with electrical power at Low Voltage or 415 Volts, this is used to power the equipment in the building directly.

Power Factor

In an ideal world the power factor for the building would be 1 indicating that the load in the building is purely resistive, however, in practice this is not the case as may items of equipment used within buildings are inductive and therefore contribute to a power factor of less that 1, typically in the range of 0.85 - 0.95. The power factor of an AC electric power system is defined as the ratio of the real power to the apparent power, and is a number between 0 and 1 (frequently expressed as a percentage, e.g. 0.5 pf = 50% pf). Real power is the capacity of the circuit for performing work in a particular time. Apparent power is the product of the current and voltage of the circuit. Due to energy stored in the load and returned to the source, or due to a non-linear load that distorts the wave shape of the current drawn from the source, the apparent power can be greater than the real power. Low-power-factor loads increase losses in a power distribution system and result in increased energy costs.

Main and Distribution Switchgear

Electrical distribution equipment is used within the building to distribute the electrical power from the point of entry to the building to the point in the building which is using the power. Circuit breakers and / or swiches are used to provide the means of switching the electrical power and providing the functions necessary to ensure that the elctrixal power is safely distributed around the building.

Point of Common Coupling

This is the point at which the electrical power supplied to the building is metered by the supply company for the purpose of determining consumption and therefore cost of the energy supplied to the building

Final Distribution

Final distribution switchgear is used throughout the building to provide switching and protection functions for the electrical power at or near its point of use.

Further reading