Low Voltage Cables
Electrical Depth and Cover
- Underground wiring systems must be installed with the minimum depth of cover and protection specified in Table 3.6 of AS3000.
- Cat C system is one in which the wiring system is laid within a channel chased in the surface of rock.
Notes:
- Cat A system is one where the wiring system is inherently suitable for installation below ground and no further mechanical protection is required.
- Cat B system is one where the wiring system is suitable for installation below ground only with additional mechanical protection provided for the cable or cable enclosure.
Below Ground Clearances
- Wiring systems installed below ground must:
- Maintain separation from other services in accordance with Table 3.7 of AS3000 (summarised in below ground separation distances).
- Use HD PVC conduits for all underground cable runs.
Services Crossover
- Separation distances outlined in below ground and above ground or as per manufactures specifications must be maintained where services cross over.
Above Ground Clearances
- Wiring systems installed above ground must maintain a separation from other services in accordance with above ground separation distances.
- Electrical equipment, including switches, socket-outlets and other accessories, in accordance with Clause 4.2.2.6 of AS 3000 must be:
- Arranged to provide a separation of not less than 300mm horizontally
- Positioned 600 mm vertically from any opening or recess in the opposite side of a wall, ceiling or floor that is required to be fire-rated.
Conduits - In Concrete
- Conduits which are completely concrete encased must:
- Be installed with adequate separation and be bunched in accordance with the Structural and Electrical Engineers’ requirements.
- Have a minimum clearance of 1.5 x times the size of aggregate.
- Be steel or HDPE in high strength concrete (anything over 40MPa). Note: avoid casting in conduits in high strength concrete if possible.
Fixing and Supports
- Fixings and cable support systems must be installed as per manufacturer’s specification.
Pits
- Electrical pits to be labelled, free of debris and sitting on a gravel bed of no less than 300mm and / or provided within drainage to the stormwater system.