Verification and Certification After a Board Replacement
An installer replaces an old fuse board with a new switchboard in a 1970s house. The new board contains a 63 A main switch, a 30 mA RCD protecting all final subcircuits, and new MCBs. During the work the installer finds: no main earthing conductor visible at the old board; a metallic water pipe bonded to the neutral bar; two circuits with no identifiable protective earthing conductor; and a subcircuit supplying a garden shed with a two-core cable and the earth return via the conduit. The client wants the certificate issued the same day so the property can settle.
1. What verification and testing must be completed before a certificate can be issued, and which findings are defects that must be rectified?
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Before certification the installer must complete verification in accordance with AS/NZS 3000, including visual inspection and testing. The tests should include continuity of the protective earthing conductor and bonding, insulation resistance, polarity, correct circuit connections, earth fault loop impedance, and operation of the RCD at its rated residual current and within the required time. The results must be recorded.
The findings are serious defects. The absence of a visible main earthing conductor means the earthing system cannot be verified; the main earthing conductor must be located or installed and connected to the earthing electrode and the MEN link. Bonding a metallic water pipe to the neutral bar is incorrect and dangerous: bonding must be to the protective earthing conductor, not the neutral. This must be corrected and the pipe bonded to the earth bar.
The two circuits with no identifiable protective earthing conductor cannot be certified as they are; the earthing must be traced, restored or the circuits made safe and clearly identified. The garden shed subcircuit using the conduit as the earth return is not acceptable; a proper protective earthing conductor must be installed, or the circuit must be disconnected. The RCD will not compensate for these earthing defects.
Only after all defects are rectified and the tests pass can a certificate be issued. The settlement date is a commercial pressure and does not justify certifying non-compliant work.
2. How should the installer handle the client's request to issue the certificate the same day?
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The installer should explain in writing that the certificate confirms the work complies with the relevant standard, and that issuing it before the defects are rectified would be false certification. The installer should provide a written list of the defects found, the tests performed, and what is required to rectify each item, with a realistic timeframe.
If the client needs documentation for settlement, the installer can provide a written statement of the work completed and the outstanding items, clearly marked as not a certificate of compliance. This protects both parties and gives the client something to take to settlement without misrepresenting the status of the installation.
Once the rectification work is complete and the tests pass, the certificate can be issued with the test results attached. The installer should keep copies of all records, including the defect list and the client's instructions, in case the matter is later disputed.