How to test pools Below is an outline of a method for inspecting and testing low voltage electrical pool installations, which incorporates a multiple earthed neutral (MEN) system of earthing. The methods comply with the principles of testing for AS/NZS 3000:2007. At all times, a safe system for performing electrical work should be in place before testing is undertaken. Tips for safe testing of existing pool installations Method 1. 2. 3. 4. Visual inspection checklist Mandatory tests Equipotential bonding Presence of voltage on exposed metal work. Visual inspection checklist The following items provide a guide on the points to be checked during the visual inspection, in order to determine that the relevant requirements of AS/NZS 3000:2007 have been satisfied. Further items for inspection can be found in CL 8.2.2. General • • Protection against direct contact with live parts, e.g. insulation and enclosure Protection against indirect contact with exposed conductive parts, e.g. double insulation or isolation transformers • Protection against hazardous parts, e.g. enclosure, guarding or screening of flammable materials, hot surfaces, and parts that may cause physical injury Protection against spread of fire, e.g. penetration of fire barriers General condition of the electrical equipment, e.g. signs of damage that could impair safe operation, disconnection of unused electrical equipment or cables. • • Wiring Systems • • Conductor size, e.g. current-carrying capacity and voltage drop Identification of cable cores • • • • • • Adequate support and fixings Connections and enclosures Particular installation conditions, e.g. underground, aerial, emergency systems Segregation from other services and electrical installations Protection against external influences, e.g. enclosure Potential risk of mechanical damage. Electrical equipment • • • • • • Isolation and switching devices for protection against injury from mechanical movement devices and motors Isolation and switching devices for protection against thermal effects, e.g. motors, room heaters, water heaters Switching devices for particular electrical equipment, e.g. socket-outlets, cooking appliances Particular installation conditions, e.g. locations affected by water, explosive atmospheres, extra-low voltage, high voltage Compliance with required standards Protection against external influences, e.g. ambient temperature, external heat sources, presence of water or high humidity, presence of corrosive substances, solar radiation etc. Earthing • • • • MEN connection Earth electrode Earthing conductors, e.g. size, identification Equipotential bonding conductors, e.g. size, identification. The minimum equipotential • • • • bonding conductor size for a pool area is 4mm², unless the conductor is incorporated in a multi-core cord supplying electrical equipment that is required to be removed for maintenance Connections, joints and terminations Protection against external influences (as above) Connection to earthing arrangements for other systems, e.g. generating sets, PV array etc Creation of earthed situation that may require earthing of additional electrical equipment • Visual inspection of any other parts relevant to the electrical installation should also be performed. Mandatory tests 1. 2. 3. 4. 5. Continuity of earthing system. Clause 8.3.3 (a) Insulation resistance. Clause 8.3.3 (b) Polarity. Clause 8.3.3 (c) Correct circuit connections. Clause 8.3.3 (d) Verification of impedance required for automatic disconnection of supply (earth fault-loop impedance). Clause 8.3.3 (e) 6. Verification of operation of residual current devices. Clause 8.3.3 (f). NOTE: If the electrical installation fails a test, that test and any preceding tests that may have been influenced by the fault indicated shall be repeated after the fault has been rectified (Clause 8.3.3). For specific values of results please consult the quick reference tables. Equipotential bonding (see clause 5.6.2.6 AS/NZS 3000:2007 Amendment 2) Confirmation of any equipotential bonding conductor to the pool shell or surround is paramount. The following sequence should be followed: 1. Ensure supply is isolated 2. Check operation of ohmmeter and set zero Ω with leads connected together 3. Test between each end of equipotential bonding conductor under test (this is all the way back to the main switchboard). Results should indicate that resistance does not exceed 0.5 Ω. (If trailing lead is used for this test, take the resistance of the lead into consideration) 4. Repeat steps 1 to 3 for each equipotential bonding conductor, e.g. bonding at metal water pipes near pool area, swimming pool attachments, swimming pool fixtures etc. Ultimately, exposing part of the reinforcing may be the only way to check some equipotential bonding connections and their associated conductors. Any fixed extraneous conductive parts of the pool structure, including the reinforcing metal of the pool shell and deck, and the concrete slab within arm’s reach of the pool, shall also be checked as these items are often missed during the construction phase. Presence of voltage on exposed metal work With all supply connected, use a voltmeter to prove the instrument is on a known live source and as an indication of voltage is present. Using the voltmeter, confirm any exposed metal parts of the pool installation, e.g. metal subswitchboards, metal water pipes, casing of hot water elements etc, are not energised by testing between the metal part and an independent earth*. Results should indicate NO VOLTAGE. These procedures have been developed with reference to AS/NZS 3000:2007. In some cases a pool installation may be effected using methods that were acceptable when that part of the electrical installation was originally installed, provided that the methods satisfy the fundamental safety principals of Part 1 of the Standard. MEA highly recommends compliance with the current standard and the use of RCDs on all pool-related circuits as a precautionary measure. *Note: An ‘independent earth’ is an earth that is completely independent of the electrical installation. That is an earth that is driven by you for the purposes of testing only. The independent earth shall be driven no closer than four metres from the point at which you are testing, or any part of the electrical installation such as the earth electrode. Disclaimer Whilst all care has been taken in the preparation of this document, the accuracy, completeness or currency of the content is not warranted or guaranteed. This document has been published as a guide only. No liability The Electrical Contractors Association, Queensland Industrial Organisation of Employers, takes no responsibility for, and will not be held liable for, any loss or damage suffered by you, your servants or agents, arising out of or in connection with the provisions of the document to you or the use of the document by you, your servants or agents.
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