Designing homes to conserve energy and use it efficiently, from sources that cause least environmental harm.

Additional on-site electrical demand

Rural properties (most typically the properties that utilise stand-alone or distributed generation systems) generally have specific features that will increase the electrical load.

On this page:

  • outbuildings
  • sewage disposal systems
  • water pumps
  • small-scale irrigation systems
  • fire sprinkler pumps
  • landscape lighting
  • automatic gates and security features.


Outbuildings may include garage, shed, workshop, granny flat and sleepout. They typically require a submain to be installed from the main meter box or the distribution board. If possible, use a common trench for conduit and cabling to connect the main and the outbuilding. Maximum demand and possible future loads should be calculated and the submain and cabling sized to suit the current and cable length.

Electric car charging at home is likely to become more common in future. Socket outlets provided for charging electric vehicles should be supplied by a dedicated final subcircuit and have a minimum rating of 20 A.

Sewage disposal system

Most rural and lifestyle blocks require a pumped on-site wastewater disposal system. These will require a power supply, typically a 2.5 mm2 two-core plus earth TPS. Some systems also include an alarm at the house for a high tank level, loss of air or pump motor failure (some local authorities require an alarm), requiring a 1.5 mm2 two-core plus earth TPS cable. Cables may be run in the trench with the sewer pipes, but the correct cover and separation from the sewer must be maintained.

Investigate the power consumption and the likely on-going maintenance costs before specifying a particular model of sewage disposal system.

Water pump

Most rural properties require a power supply to operate a bore pump or a pumped rainwater system. The trench for the water pipes may also have the power cables laid in it.

Fire sprinkler pump

Fire sprinkler systems generally require a pump, which may be the water pump if it is sized correctly. However, the sprinkler system security can be increased by powering the pump directly from the meter box, so if a fire starts inside the house, the pump power supply is not affected.

Security and landscape lighting and power

Rural properties generally require security lighting and may include feature lighting. Utilise existing trenches to install cables for landscape and security lighting and external power.

Security and landscape lighting considerations include:

  • light pathways and stairs with discreet low-level lighting
  • avoid glare and direct lights away from the main viewing points
  • minimise light pollution and wasted light, e.g. when using uplighting, use glare controllers and suitable reflectors to avoid excessive uplighting, which can affect birdlife and the view of the night sky
  • locate control switches in convenient places, e.g. adjacent to an external door leading to the area to be lit
  • specify cut-off luminaires and warm white light sources
  • highlight entertainment areas and silhouette sculptural plants or forms
  • light the background to give additional depth and distance to the night view.

Automatic gates, audio and video links and cameras

The installation of a security system often includes controlled gates, an intercom system and security cameras. Where these are required, cabling can usually be included in the mains trench, so planning for these should be carried out in the early stages of the design. If they are planned for a future installation, the prewiring should be carried out during the initial installation.


Updated: 16 November 2016