When earthing structural metalwork what is an appropriate sized conductor ? Clause 5.4.6.3 states : “ Earthing of parts of structural metalwork , including conductive building materials , may be affected by the connection of a protective earthing conductor of appropriate size at one point of the metalwork provided that the resistance between the earth bar and any part required to be earthed does not exceed 0.5Ω .” |
The appropriate size can be determined by Clause 5.3.3.1.2 . The cross-sectional area of any copper protective earthing conductor required for the protection of any portion of an electrical installation shall be determined either — ( a ) from Table 5.1 in relation to the cross-sectional area of the largest active conductor supplying the portion of the electrical installation to be protected ; or ( b ) by calculation , in accordance with Clause 5.3.3.1.3 . |
AS / NZS 3000:2007 |
Clause 5.3.3.1.2 |
I have been issued a defect notice by my electricity distributor as one pole of my two-pole private overhead electric line has only 30mm of sound wood . They say I need to install an underground supply as I am in an area of high bushfire risk . Is this correct ? |
Yes , a private overhead electric line that is to be constructed or substantially reconstructed in a hazardous bushfire risk area must be placed underground . Substantial reconstruction means in the case of a private overhead electric line the replacement of more than 20 per cent of the wiring or more that 20 per cent of the poles in a line supporting the wiring . The replacement of one pole of a two pole overhead private electric line is 50 per cent and exceeds the 20 per cent . |
Electricity Safety ( Installations ) Regulations 2009 |
Regulation 220 |
Can I install underground consumer ’ s mains at a depth of 300mm under a concrete driveway in compliance with clause 3.11.4.4 of AS / NZS 3000:2007 ? |
No , consumer ’ s mains are required to be installed with a minimum depth of cover of 500mm from the top of the additional protection to the surface of the ground . |
Electricity Safety ( Installations ) Regulations 2009 |
Regulation 214 ( 1 ) |
Can a concrete house slab be used as an earth electrode ? |
The connection of the electrical installation earthing system to the general mass of earth shall be achieved by means of an earth electrode . Materials and dimensions of earth electrodes shall be selected to withstand corrosion and to have adequate mechanical strength . Consideration should be given to the soil and environmental conditions . Earth electrodes shall be of a type and shall be installed in accordance with Table 5.2 . Exception : Conductive reinforcement of ( a ) concrete foundations embedded directly in the soil ; or ( b ) concrete foundations of a building or floor slab in contact with the ground and not impeded by a continuous insulating barrier , may be used in lieu of an electrode specified in Table 5.2 . |
AS / NZS 3000:2007 |
Clause 5.3.6.1 & 5.3.6.2 . |
I am inspecting a replaced switchboard – am I required to inspect the whole of the installation ? |
No , but the licensed electrical inspector has to attend the electrical installation address stated on the certificate of compliance ; and : »» carry out inspection of the electrical installation in accordance with the Australian / New Zealand Wiring Rules and these regulations »» carry out testing of the electrical installation in accordance with regulation 231 »» in circumstances where the inspector knows or should be reasonably expected to know that the premises or land related to the electrical installation work being inspected will be electrically unsafe to connect to electricity supply or unsafe to use , has stated on the certificate of inspection that the installation appears to be electrically unsafe . |
Electricity Safety ( Installations ) Regulations 2009 |
Regulation 242 |