This section addresses issues relating to the specification and detailing of electrical wiring and fittings. The following should be considered a guide only.
Work shall commence as soon as practical after, but not before,
(a) the Builder has issued:
- a written order
- the relevant contract drawings, specifications and schedule of work
- written approval of any details provided by the Contractor
(b) the earthworks have reached a stage to enable underground cables to be roughed in, or
(c) the building frames have been constructed, sufficient for the wiring to be run.
Approvals
The Contractor shall obtain all relevant approvals and provide to the Builder the appropriate certificates.
Supply Authority Rules
The installation must be undertaken in accordance with the Supply Authority’s requirements as well as the relevant Australian Standards and codes.
Rating of Circuits
The rating of the service mains and the final sub circuits should allow for growth of at least 25% of requirements.
Capacity of Switchboard
The switchboard shall include 25% extra capacity to allow for future circuits including provision in service mains for additional capacity and space on switchboards.
Existing Services
The Contractor shall disconnect, terminate and remove any obsolete services. If required to divert existing services, at least three day’s notice shall be given to the Builder.
Roughing-In and Provision for Services
Chasing of brickwork to provide for electrical and plumbing services can severely weaken the structure. These services should be carefully planned in advance and roughed in to minimise chases. Where practical, restrict them to framed walls.
Dual Occupancy and Multiple Occupancy Units
Where separate title is required for more than one unit, ensure that the electrical and other services are run separately to each unit, considering the need for access for metering purposes and the need for security from tampering.
Energy Efficient Homes
The increasing interest in energy efficient homes requires special consideration. Building Regulations and Australian Standards in this area are emerging, aalthoug it is unlikely in the immediate future that such provision will be a normal part of a house construction. Considerations include provision for solar power and cogeneration.
Telecommunications Requirements
For the purpose of this section telecommunications is taken to mean any signal cables including telephone, data, security (including CCTV) and entertainment systems including television (either by master antenna (MATV) broadband cable or by satellite).
There is an increase in the use of devices that communicate electronically (including computers and networked peripherals) around the home. This requires consideration of the permanent wiring requirements during construction. The likelihood that there will be an increase in the networking of domestic devices including television/video and audio systems, recording devices, security systems and even domestic appliances could require significant additional cabling. Wireless and powerline systems may be suitable alternatives where cabling is more expensive however for a new construction wired networks are the preferred solution.
A major challenge is that there are a number of cabling standards and others are likely to emerge. Furthermore, powerline communications systems are becoming available using the domestic electrical wiring to distribute broadband data. There remain question marks about this technology as to whether it might result in unacceptable interference.
Wireless systems (Wireless LAN or WLAN) are also becoming more readily available, although users should be aware of frequency sharing issues, bandwidth limitations and network security issues.
Cabling options include twisted copper pairs (eg Cat 5 or Cat 6 cable), coaxial cable systems and optical fibre
Considerations include television and master antenna TV systems, satellite antenna, cabling requirements to the roof, equipment location for wireless or wired hub. A wireless hub location should be selected for good propagation around the premises and isolation from other users (other properties).
Communications Equipment Space
The purpose is to allow the interconnection of cables to outlets around the multi unit dwelling or house (including telephone and broadband cable) at which electronic hub equipment can be added if and when required. A multi unit dwelling may have a (secured) common equipment location where all cables that enter the premises terminate and are reticulated to a sub equipment location in each unit. Considerations include:
- Cupboard shelf
- Ventilation
- Power (also required for access for power line communications (PLC): should be cabled to optimise as the hub location for PLC)
- Cable pathway (eg 25mm conduit into cabling space (eg ceiling or under floor)
- Includes access for telephone cabling and broadband cable
- Provision for lightning protection (arrestors on external lines and at power points).
Cabling
Cabling requirements are specified by the Australian Communications Authority (ACA) and the Australian Communications Industry Forum (ACIF). Some of the relevant requirements are specified in the following table:
- AS/ACIF S009:2001 Installation requirements for customer cabling
- AS/ACIF S008:2001 Requirements for authorised cabling products
- AUSTEL TS 009-1997 Installation Requirements for Customer Cabling (Wiring Rules)
- ACA TS 001-1997 Safety Requirements for Customer Equipment
- ACA TS 008-1997 Requirements for Authorised Cabling Products
Copies of these standards may be obtained from
http://www.standards.com.au/catalogue/script/PortalTelecoms.asp
It is recommended that licensed cable installer be engaged for telecommunications cabling (desirable to have cable installer licensed for both electrical and telecommunications).
Telecommunications Cable Types
As far as possible standardise on one cable type (for telephone and data) and terminations where it can meet current and future requirements.
Telephone Cabling
The use of cordless handsets increases in popularity and, whilst this could avoid the need for extensive cabling, provision of at least one point where a fixed telephone can be installed is important as cordless telephones are unsuitable (without a no break power supply in the base station unit) when the mains power fails. This is an important factor to consider in regard to “life line” (eg 000) calls and is relevant to consideration of telephone systems which are supported from a computer network.
Suggested locations for cable points include a wall mount in the kitchen or table mount locations in the living room and master bedroom. A point in the study is advisable for a computer modem, which may utilise the data cabling. Typically run the same (high performance) cable type as used for data to standardise on cable type.
Data Cabling
Where data cabling required (assume wider cabling may be supported by wireless LAN or power line communications. Typically run the same (high performance type) and separate cable as used for telephone. Allow a minimum of one point in the study; it may be advisable to extend the coverage to other rooms.
Other Cabling Considerations
The designer should consider:
- Video Cabling
- Security Cabling
- Provision for cable pathways for future cabling
- Access from cabling termination point to other locations in residence
- Access for new street cabling
- Access to Residence
- Pressure to put street cable underground.
Ideally the designer should provide for underground conduit between street and house entry. It may not be practical to excavate later, due to the risk of damage to existing service. Conduit can become blocked with sediment rendering it unusable or requiring cleaning. Consider the cable pathway required between underground (or aboveground including broadband cable) cable entry and in house equipment hub.
