Electrical practices: construction and demolition sites

Transcription

1 FACT SHEET Electrical practices: construction and demolition sites This fact sheet provides an overview of the requirements shown in AS/NZS 3012: 2010 Electrical installations construction and demolition sites (AS/ NZS 3012), which is called up as a mandatory standard by clause 163 of the Work Health and Safety Regulation 2011 (WHS Regulation). AS/NZS 3012 has replaced the Electrical Practices for Construction Work Code of Practice 2007, which was revoked with the introduction of the WHS Regulation on 1 January The standard sets out minimum requirements for the design, construction and testing of electrical installations that supply electricity to appliances and equipment on construction and demolition sites, and for the in-service testing of portable, transportable and fixed electrical equipment. Note: Electrical work carried out on electrical installations and electrical equipment used on construction and demolition sites must also be carried out in accordance with AS/NZS 3000: 2007 Wiring rules, except as varied by AS/NZS 3012 where applicable additional controls apply. Supply (Refer to section 2 of AS/NZS 3012) Construction wiring must be supplied from: an electricity distributor s main an existing switchboard in the permanent installation of the premises a low voltage generator complying with the principles of AS2790, which must be installed in accordance with AS 3010, or an inverter complying with the requirements of AS/NZS Construction wiring must: not be tied, bundled, or grouped with permanent wiring not be fixed to free standing fences that have no fixed posts (or equivalent means of support) be protected against mechanical damage (medium or heavy duty or corrugated conduit of insulating material, armoured cable, flexible electrical hose) be marked and be readily distinguishable from permanent wiring by using iridescent yellow tape spaced at intervals not exceeding five metres and marked with the words construction wiring be positioned to avoid crossing roadways or access ways where cranes, high loads or heavy machinery may travel. If this is not possible, an effective means to minimize the risk of vehicular contact with the overhead wiring system must be provided (such as insulated flagged catenary wires six metres on either side of the overhead wiring and 0.6 metres below the lowest point of the overhead electrical cable). Please note, all construction wiring, including overhead type, must be insulated. February 2013

2 Switchboards installed on construction and demolition sites (Refer to section 2.3 of AS/NZS 3012) Switchboard installation and location: must be installed in accordance with AS/NZS 3000: 2007 Wiring rules must be readily accessible and must be protected from damage during the course of the construction or demolition work must be mounted on a pole, post, wall, floor or other structure of stable and free standing design that takes into account any external forces that may be exerted on the switchboard must be marked with the source of the supply and where it originates from for multi-level buildings, be positioned in a manner that eliminates the need for flexible cords or cables to be run between floor levels. Note: Alternative switchboard construction and supply system (plug and socket arrangement) is shown in Appendix K of AS/NZS Switchboard construction Switchboards must be constructed of robust material capable of withstanding mechanical damage. The enclosure of the switchboard must have a minimum degree of protection of IP23 *. Energized (live) parts must be effectively protected at all times against contact by workers. An insulated or covered tie bar must be provided for anchorage of flexible cords to prevent strain on the plugs and socket outlets. Switchboard doors must not be of the removable type (unless with a tool) and be fitted with a locking facility (for locking overnight or when not in use). They must also be fitted with means for retaining the door in the open position. Switchboards must have a cut out (not sharp to prevent cables being cut, ie by providing brushing or plastic hose around it) in the bottom plate to allow safe entry of electrical leads with the door closed. A label must be fixed to the switchboard stating KEEP CLOSED RUN ALL LEADS THROUGH BOTTOM. If more than one switchboard is located on a site, markings must be provided to distinguish one switchboard from another. Switchboards must be marked with an electric shock symbol and a danger sign (as per below) warning workers of the presence of energized or live parts within the switchboard. * Note: IP23 refers to the degree of protection provided by the enclosures of electrical equipment. According to AS60529: 2004 Degrees of protection provided by enclosures (IP Code), IP23 refers to an enclosure (in this case an electrical switchboard) that is protected against access to hazardous parts with a finger and also protected against water spraying. 2

3 Isolating switches, RCDs, socket outlets, auxiliary socket outlet panels, portable socket outlet panels, generators and inverters (Refer to section of AS/NZS 3012) Isolating switches/main switches Each switchboard must be provided with one marked isolating switch which, if switched off, will interrupt supply to all final sub-circuits and sub-mains originating from the switchboard, including socket outlets mounted on the switchboard. The switchboard must be provided with a means to prevent electrical equipment from being inadvertently energized while undertaking work on electrical installations (provision for fitting a padlock or located within a lockable space or enclosure). Main switchboard isolating switches must be marked MAIN SWITCH and the distribution board isolating switches must be marked DISTRIBUTION BOARD ISOLATING SWITCH. RCDs ** All final sub-circuits of construction wiring must be protected at the switchboard where the sub-circuits originate by a residual current device (RCD), with a maximum rated residual current of 30mA, that operates in all live (active and neutral) conductors. All appliances, luminaries and other electrical equipment must be supplied from an RCD protected circuit that is fixed at the switchboard or incorporated into the socket-outlet or incorporated into a portable socket-outlet assembly. Socket outlets Socket outlets must be rated at not less than 10A. Single-phase socket outlets must be individually controlled by a double-pole switch (active and neutral conductors are switched). Portable socket outlet assemblies (PSOA) must comply with AS/NZS 3190 and be of class H (should be marked with these requirements) must have an overload protective device, RCD and plugs intended for connection of low-voltage socket-outlet flexible cable feeding the PSOA must be the heavy duty sheathed type not longer than 2m. ** Note: Testing and inspection requirements are discussed further in this fact sheet. 3

4 Auxiliary socket outlet Assemblies (ASOP) must be: of robust construction to withstand mechanical damage and have a minimum IP23 rating located at a height of 1.2 to two metres above the floor level and be securely mounted to a fixed structure or a structure designed for that purpose supplied by an RCD protected circuit at the switchboard it originates from provided by a clearly marked isolating switch that controls the incoming supply. Incoming supply cable must have a minimum cross sectional area of 4mm 2 provided by means to relieve strain on plug and socket outlets of flexible cables. Example of an ASOP Cord extension sets (commonly known as extension leads) A flexible cord must be the heavy duty sheathed type (not green in colour) and each conductor in the flexible cord must be no less than 1mm 2 in cross-sectional area. The plug and socket on either side of a cord extension set must be compliant with the relevant standard for their construction. The maximum length of a flexible cord, for a given conductor cross-sectional area, must comply with table 1 below. A cord extension set must not to be joined so that the total length of any combination exceeds the relevant maximum value specified in table 1. Note: Electrical portable outlets devices (EPODS), for example domestic type power boards, double adaptors and three pin plug adaptors (piggyback), are not allowed on construction and demolition sites. Table 1: (Maximum lengths of flexible cords and flexible cables) as per AS/NZS 3012: 2010 Electrical installations construction and demolition sites. Table 1: Maximum length of most commonly used single phase cord extension set Current rating (A) Conductor size (mm 2 ) Maximum length (metres) / Note: Lengths quoted for flexible cords are taken from AS/NZS 3199 and are based on a voltage drop of 5% of 230V at rated current for the conductor size. 4

5 Generators and inverters Low voltage generators (complying with AS 2790) must be connected in accordance with AS/NZS All sub-mains, sub-circuits and switchboards supplied by a generator must be protected as per requirements outlined in this summary. Generators and inverters providing electrical supply via permanently connected RCDs must have a maximum tripping current of 30mA Isolated winding generators and isolated inverters must only be used to supply a separated circuit for electrical equipment installed in accordance with AS/NZS 3000: 2007 Wiring rules, and each winding must supply not more than one item of Class I (earthed conductive parts) electrical equipment. Lighting, lift shafts, transportable structures (Refer section of AS/NZS 3012) Lighting Where more than one lighting circuit is installed, the lighting circuits must be distributed between RCDs. The recommended minimum lighting level for walkways is 40 lx, and 160 lx *** for general areas. Lamps in luminaires must be protected against mechanical damage. Emergency lighting must be sufficient to allow the safe egress of all workers from the site. It must be capable of running for a minimum of one hour in case of loss of normal lighting in the area. Edison screw type lamp holders must be connected to the supply with the neutral conductor connected to the outer contact. Festoon lighting must be connected to an Extra low Voltage power source (<50 V a.c). It must be suspended at a minimum height of 2.5m or above or directly below the ceiling. Portable luminaries (eg flood light tripods) must have a minimum degree of protection (refer to AS 60529), a mechanical guard on the lamp and adequate stability. Lift shafts Construction wiring dedicated to the installation of lift shaft equipment must be fed from a separate final sub-circuit at the switchboard and protected by 30mA RCD. Circuit breakers must be locked and tagged to prevent the inadvertent isolation of supply to the lift shaft by others onsite. False cars (guided work platforms) must be supplied from a minimum 230V, 20A socket outlet on a final subcircuit protected by a 30mA RCD. Supply cable must be of the heavy duty type, minimum conductor size 4mm 2. The supply cable must be installed in a way to minimize mechanical damage and of sufficient length to cover the full length of the lift shaft. Transportable structures Electrical installations of transportable structures must comply with AS/NZS 3001 and the following: The installations must be supplied from a sub-main or final sub-circuit originating at a circuit breaker on a switchboard and installed as construction wiring. The installations must be supplied from a flexible cord and plug with a specific socket outlet with a degree of protection not less than IPX4. They must also be individually protected by a circuit breaker of a rating not greater than the socket outlet and be RCD protected. The supply cord must have a minimum cross sectional area of 2.5mm 2 and not longer than 15 metres. All socket outlets (inside/outside) must be RCD protected and only be used for equipment and lighting within the transportable structure or immediately adjacent the exterior. (Note: double pole switches must be used for socket outlets.) *** lx: lux which is a measure of light illuminance and could be measured using a special hand held device. 5

6 Inspection, testing, record keeping (Refer to section of AS/NZS 3012) Inspection and testing All construction wiring, switchboards and transportable structures must be inspected and tested by a licensed electrical worker (electrician) following the initial installation and in a period not exceeding six months (refer to table 2). For new equipment, prior to the initial introduction it must be inspected for obvious damage before being placed into service. All other electrical equipment including power tools, flexible cords, cord extension sets (extension leads) and portable socket outlet assemblies and portable RCDs** must be tested and inspected according to the methods in AS/NZS 3760 and in a period not exceeding three months. Inspection and testing can be carried out by a competent person (trained in use of RCD testers and Portable Appliance Testers PAT) or a licensed electrician. **The RCD tests referred to above, test the tripping time which should be less than 300ms. A push button test is required every time a portable RCD unit is used, and monthly on fixed RCDs. This could be carried out by the user (worker) after being instructed on how to do it. For hire equipment, inspection prior to each hire and testing at not greater than monthly intervals. If hire equipment remains on site, then table 2 applies. Compliant equipment and equipment new to service must be fitted with a durable non-metallic tag that clearly states the date it was inspected and the next date of inspection. It should also include the name of the person that performed the verification and the standard it was tested to (AS/NZS 3760). Colour coded tags for each period are optional. Non-compliant equipment must be withdrawn from service immediately and labelled with suitable warning against further use. If sent for repairs, it must be re-tested once returned to site. Record keeping Records of inspection and tests must be kept for the duration of the construction/demolition job. The following should be recorded and be available for inspection at all times. Register of all equipment. Record of formal inspections and tests. Repairs register and record of faulty equipment, where applicable. Construction wiring must be inspected according to AS/NZS 3000: 2007 Wiring rules checklist, which includes, but is not limited to: visual inspection, continuity of earthing, insulation resistance, polarity, correct circuit connections and RCD trip time values. Note: electronic records (ie computer databases, excel spread sheets etc) are acceptable. Table 2: Periodic verification intervals (AS/NZS 3012: Electrical installations construction and demolition sites) Table 2: Inspection and testing intervals Equipment class Construction wiring, including switchboards Re-locatable structures, fixed and transportable equipment Portable equipment and flexible electrical cords (extension leads) Equipment in amenities and site offices Portable RCDs push button test Portable RCDs operating time Fixed RCDs push button test Fixed RCDs operating time Hire equipment Testing intervals Inspected and tested at time of installation, then re-inspected every 6 months 6 months 3 months 3 months Before each use of equipment 3 months 1 month 12 months Upon introduction to service, then in accordance with the testing intervals appropriate to the equipment class. 6

7 Appendix 1 Guide to arrangement of switchboards, construction wiring and equipment Refer to Appendix J of AS/NZS 3012:

8 Appendix 2 AS/NZS 3012: 2010 Electrical installations: construction and demolition sites checklist Inspection checklist Inspected by Inspection date (DD/MM/YYYY) / / Clause AS/NZS 3012 requirements / 1.2 All wiring installed according to AS3000 Wiring rules in addition to AS3012 requirements All electrical equipment and lighting supplied from a 30mA RCD protected circuit breaker(s) Source of supply identified Switchboard readily accessible (ab) Switchboard of robust construction with a minimum IP23 rating (c) Live parts effectively protected and a warning sign attached along an electric shock symbol (d) Insulated tie bar for extension leads to prevent strain on socket/outlet (e) Switchboard door is lockable, non-removable without a tool and fitted with a retention device to stay in open position (e) Switchboard has means of safe entry of leads and a label: KEEP CLOSED RUN LEADS THROUGH BOTTOM Switchboard mounted on a pole, structure, wall or suitably designed free standing design Switchboard has a main isolation switch capable of isolating all downstream circuits Main switch capable of being locked or within a lockable space Main switch labelled appropriately: MAIN SWITCH or DISTRIBUTION BOARD ISOLATION SWITCH or similar Construction wiring installed in appropriate conduit to protect against mechanical damage Construction wiring labelled with yellow tape with words construction wiring at distances not longer than 5m Extension leads supported by stands or insulated hooks Adequate lighting provided for safe work Lighting is mechanically protected Emergency lighting adequate for safe exit of workers (if applicable) If a lift shaft is present, the final sub-circuit feeding it is locked and tagged to prevent inadvertent isolation of supply. 2.9 Socket outlets in site sheds and other transportable structures are RCD protected Portable equipment including power leads are inspected at three-monthly intervals Portable RCD s trip time is tested every 3 months Switchboards, wiring and site sheds are inspected at six-monthly intervals Register available for equipment and includes records of testing and tagging, RCD trip time results and list of repaired equipment. Action required Re-inspected by Compliance date (DD/MM/YYYY) / / Note: For more information and guidance material on construction work carried out in the vicinity of overhead wiring that is not classified as construction wiring discussed in this bulletin, safeworkaustralia.gov.au and search for Code of practice: Working in the vicinity of overhead and underground electric lines. The Guide: Work near underground assets (catalogue no. WC01419) provides more information for work carried out near underground assets (eg power lines, telecommunications, gas, water). It can be accessed at workcover.nsw.gov.au or by clicking on the following link: Guide: Work near underground assets. 8

9 Disclaimer This publication may contain work health and safety and workers compensation information. It may include some of your obligations under the various legislations that WorkCover NSW administers. To ensure you comply with your legal obligations you must refer to the appropriate legislation. Information on the latest laws can be checked by visiting the NSW legislation website legislation.nsw.gov.au This publication does not represent a comprehensive statement of the law as it applies to particular problems or to individuals or as a substitute for legal advice. You should seek independent legal advice if you need assistance on the application of the law to your situation. WorkCover NSW Catalogue No. WC03959 WorkCover Publications Hotline WorkCover NSW, Donnison Street, Gosford, NSW 2250 Locked Bag 2906, Lisarow, NSW 2252 WorkCover Assistance Service Website workcover.nsw.gov.au ISBN Copyright WorkCover NSW 0213