Evidence shall show that knowledge has been acquired of safe working practices and disconnecting and reconnecting fixed wired electrical equipment connected to a Low Voltage supply. All knowledge and skills detailed in this unit should be contextualised to current industry practices and technologies. KS01-EP012A Electrical Safety Principles Evidence shall show an understanding of electrical safety principles to an extent indicated by the following aspects T1 The basic electrical circuit encompassing: elements of a simple electric circuit (supply, control switch, protection device and load). definition, the symbol and the abbreviation of the unit for electromotive force, potential difference, current, resistance types of electrical load need for devices to afford electrical protection and the mechanisms used in protection devices including resetting symbols for the components of a basic electrical circuit connection of the circuit from the schematic diagram a.c supply (both single and three phase) and d.c. supply correct connection and use of voltmeters and ammeters, including the selection of correct range in terms of magnitude and whether the supply is a.c. or d.c. need for isolating, testing and tagging electrical circuits isolation, testing and tagging accessories in a simulated environment connecting a simple electrical circuit including supply, control switch and load. measuring voltage and current within a simple circuit T2 Relationships in an electrical circuit encompassing: relationship between Voltage, Current and Resistance connection of meters to determine resistance from voltmeter and ammeter readings using a variation of the Ohm’s Law relationship predicting changes in circuit parameters for altered values of voltage, current and resistance definition of ‘power’ in electrical terms (for d.c. or resistive a.c. circuits) using circuit readings determine power using the appropriate equations, symbols and unit abbreviations including the use of multiples and sub multiples T3 Electrical diagrams encompassing: symbols used for fuse, circuit breaker, isolator, normally open contacts, normally closed contacts, coil, energy meter, a.c. motor, transformer. using a ‘block diagram’ as means of developing concepts and understanding producing a block diagram of a simple circuit function of single line diagrams including their application in three phase systems definition of a ‘circuit’ or ‘schematic’ diagrams wiring diagrams connecting a simple circuit using a schematic diagram noting the wide degree of variety in the way the conductors may be run producing the wiring diagram of the connections used in following the schematic diagram connecting a simple circuit following a wiring diagram producing a schematic diagram from the wiring diagram T4 Test equipment – selection and care encompassing: fault currents and the implications of incorrectly connecting a meter to a high fault current source category ratings of multimeters in terms of their breaking capacity (fault current interruption) and identification of the appropriate category of instrument for typical domestic work and for typical commercial work. regulatory requirements in regard to the maintenance and testing of test instrumentation. steps and procedures for the safe use, care and storage of electrical instruments. selecting test equipment for given situations. T5 Test equipment - Voltage measurement encompassing: voltage measurement -meters connected in parallel operation of series test lamps construction of a set of series test lamps with emphasis on safety requirements using a set of series test lamps operation of neon test pencils and test screwdrivers with emphasis on the limitations of their safe use operation and limitations of voltage probes including their limitations using an analog multimeter for voltage measurement ensuring the following - setting zero, correct scale; ac or dc, polarity and magnitude, avoiding parallax error and estimating between division readings using a digital multimeter for voltage measurement ensuring the following - correct range and no active conductors are connected to any meter earth T6 Test equipment - Resistance measurement encompassing: voltmeter-ammeter method of resistance measurement measuring resistance in a simple circuit using the voltmeter-ammeter method with emphasis on the correct choice of long or short shunt measuring resistance in a simple circuit using an analog multimeter ensuring the following - setting zero, selecting correct range, estimating of between division readings measureing resistance using a digital multimeter insulation resistance, and list the required minimum values for insulation resistance for low voltage wiring and low voltage equipment (insulation resistance between active and earth the value for appliances incorporating heating elements) insulation resistance needs to be measured at higher than supply voltage and list the voltages to be used conducting insulation resistance tests using a hand held tester after checking for zero and meter calibration continuity and what a continuity tester does checking the polarity of a three core extension cord using a continuity tester T7 Test equipment - Current measurement encompassing: advantage(s) of the clip-on method of current measurement measuring current in a simple circuit using a multimeter on the correct current range and explain why a series connection must be used measuring current using a clip-on (tong tester) taking each circuit conductor in turn.  KS02-EP012A Disconnect and Reconnect Composite Electrical Equipment Evidence shall show an understanding of disconnect and reconnect composite electrical equipment to an extent indicated by the following aspects T1 Cable connections encompassing: construction of typical power cables. principle of operation of the following types of terminals stud, screw, tunnel, faston and soldered cable preparation and terminating methods appropriate to each type of terminal, including any special requirements which apply terminating cables using all of the above terminal types employing the correct preparation and the relevant terminating tools including the correct size soldering equipment T2 Protection for Safety encompassing: dangers associated with earth-faults. protection of persons against electric shock from earth-faults. maintaining a low earth-fault current path resistance. components in an earth-fault current path. testing the resistance of a fault-current path. regulatory issues/requirements/limitations in regards to working live T3 Safety testing preparation and procedures encompassing: faulty earth-fault current paths using safe working practices when carrying out fault finding work. Identification of earthing system components. unsatisfactory resistance of a fault-current path. actions to rectify unsatisfactory resistance of an earth-fault current path or insulation. T4 Isolating supplies encompassing: regulatory requirements in regards to working de-energised, and ensuring and maintaining isolation reasons for advising all personnel likely to be affected: preventing others wanting to remake supply reason for isolation and approximate time of outage to allow planning of alternate activities identification the type and arrangement of circuits supplying equipment that is to be disconnected availability of supply is tested at an appliance about to be disconnected locating isolation device/s e.g. lockable adjacent isolating switch or fuse/circuit breaker at a distribution board usually identified at the appliance determining the method of isolation to be used; which available device isolating a supply at a fuse, the fuse wedge is removed only after the appliance is turned off and why the empty wedge is replaced once the fusible link has been removed tests to determine if an appliance/equipment is turned off when isolating at a fuse/circuit breaker use of and reason for danger tags at the point of isolation reason for the following steps: testing on a known live supply, testing for isolation, retesting on a known live supply after confirming isolation T5 Disconnecting composite electrical equipment - ELV encompassing: identification of the type and arrangement of circuits supplying equipment that is to be disconnected from a ELV single phase and/or multiphase supply of voltages up to 50 V a.c. or 120 V d.c. procedures that ensure the safe isolation of the supply to equipment which is to be disconnected. disconnecting isolated equipment from fixed wiring with minimal damage to wiring system. after ensuring no visible faults or damage, and the recording of conductor connection sequence termination practices in regard to disconnected wiring T6 Reconnecting composite electrical equipment - ELV encompassing: importance of checking the new composite electrical equipment nameplate details against those of the composite electrical equipment being replaced need for high insulation resistance and the need to test insulation of 400 volt composite electrical equipment at 1000 volts and identify the minimum acceptable value of insulation resistance between active and earth generally and the value for composite electrical equipment incorporating heating elements. testing procedures: testing on a known live supply, testing for isolation and retesting on a known live supply after confirming isolation need to disconnect circuit cables before undertaking insulation resistance testing compliance testing the composite electrical equipment: insulation resistance test and continuity test need to ensure the following steps are taken when terminating cables: stranded conductors are twisted tightly together, appropriate lugs are used rather than simple loops under a nut e.g. soldered lugs or Ross Courtney, Stanco or other solderless variety, shake proof washers are used, cables are not left under physical stress, cables are protected when passing through metal openings, conductors are doubled in tunnel connectors T7 Disconnecting composite electrical equipment - LV encompassing: identification of the type and arrangement of circuits supplying equipment that is to be disconnected from a single phase and/or multiphase supply of voltages up to 1000 V a.c. or 1500 V d.c. procedures that ensure the safe isolation of the supply to equipment which is to be disconnected disconnection of isolated equipment from fixed wiring with minimal damage to wiring system after ensuring no visible faults or damage, and the recording of conductor connection sequence termination practices in regard to disconnected wiring T8 Reconnecting an composite electrical equipment – LV encompassing: importance of checking the new composite electrical equipment nameplate details against those of the composite electrical equipment being replaced need to visually inspect and test the equipment electrical characteristics using suitable test equipment to ensure equipment is safe to connect in regard to sufficiently high insulation resistance, arrangements for protection against indirect contact are undamaged and in place, appropriate IP rating, and arrangements for protection against dangers of mechanical movement are undamaged and in place compliance testing of the fixed equipment, ie insulation resistance and continuity testing the disconnected equipment for faults (open circuits, partial open circuits, short circuits, partial short circuits and earth faults), and recognise any unsatisfactory test results obtained procedures for equipment with unsatisfactory results - unsuitability for reconnection identification of the type and arrangement of circuits supplying equipment that is to be reconnected to a single phase and/or multiphase supply of voltages up to 1000 V a.c. or 1500 V d.c. procedures ensuring isolation of supply process to establish the integrity of the circuit to which the disconnected equipment is to be connected, including: testing the resistance between the protective earthing conductor and neutral conductor as applicable is sufficiently low ie not greater than 2 ohms insulation resistance of the active conductors is greater than 1 megohm engaging appropriately qualified person to rectify any noncompliance appropriate cable termination practices reconnection of equipment to fixed wiring with minimal damage to wiring system continuity between exposed conductive parts of the equipment and the main earth or metal switchboard enclosure restoring supply after ensuring correct connections, and all safety requirements have been met testing the supply at appliance / equipment restoring all mechanical protection eg terminal covers checking operation of reconnected equipment T9 Produce documentation and reports encompassing: need to produce status reports and documents to locate and identify isolation mechanisms for a wide range of circuits and associated loads. production of reports and documents to use a suitable procedure to safely disconnect a component from a single phase supply and/or multiphase supply. content required in reports and documents used to safely determine the suitability of a component for reconnection to supply. producing reports and documents for the safe reconnection/commissioning of a component to the supply. T10 Enterprise reporting and recording system encompassing: purpose and extent of maintaining work activities records in an enterprise types of records for maintaining work activities in an enterprise methods for recording and maintaining work records work records for regulation requirements producing enterprise records and documents for the safe reconnection/commissioning of a component to the supply. |