2. EKAS 2.19.29 Disconnect & Reconnect UEE31307 Certificate III in Refrigeration and Air Conditioning Stage 2A Units: UEENEEPOO1B Chris Hungerford Sunday, August 16, 2015

3. Voltage measurement Voltage measuring devices have high values of internal resistance, however a series test lamp has a low resistance whereas voltmeter has a very high internal resistance. A voltage measuring device is connected in parallel across the terminals you are measuring. The highest range on the voltmeter should be chosen when beginning your measurements. 2.19.29.A

4. Resistance measurement An ohmmeter has a it’s own internal power supply and should not be placed across a live supply. 2.19.29.A

5. Handheld test tool safety Last known earthly residence of automotive fuse used to replace original fuse How not to save time... 2.19.29.A

6. Handheld test tool safety Probe tips burned off 250V fuse didn’t open in time The wrong meter to use on a power circuit. Fingerprints burned into probes 2.19.29.A

7. Testing Practices Ensure that the correct testing device and scale are chosen Ensure that your hand and test probes are dry and clear of conductive materials. Test the testing device on a known source. Ensure that you do not contact the supply with yourself. Allow plenty of working space. If possible the first probe to contact should be a neutral or earth potential. Do not leave live exposed terminals when finished. 2.19.29.A

8. CAT IV-600 V CAT III-1000 V What’s the bottom line? If you work on power circuits, you need a CAT III-600 V or CAT IV-600 V/ CAT III 1000 V meter. Look for the CAT rating and voltage rating marked near the input jacks. –CAT or voltage rating alone can be misleading Look for independent certification. UL 3111 2.19.29.A

9. Electricity Safety Regulation 2002 18 Employer or self-employed person to ensure suitability of testing instruments (1) This section applies to the following— (a) an employer of a person required to perform tests on electrical work or safety equipment; (b) a self-employed person required to perform tests on electrical work or safety equipment. (2) The employer or self-employed person must ensure— (a) the test instruments used for the testing are designed for, and capable of correctly performing, the required tests; and (b) if a testing instrument can not be visually confirmed as being correctly functioning and safe—that the instrument is tested at least every 6 months to ensure it is in proper working order; and (c) records of tests performed are kept for at least 5 years. Maximum penalty for subsection (2)—40 penalty units. 2.19.29.A

10. M.E.N. system MEN point 2.19.29.B

11. 11 Requirements for electrical work (1)An employer or self-employed person must ensure that, unless the circumstances required under this division for the performance of live work apply, live work is not performed. Maximum penalty—40 penalty units. ELECTRICAL SAFETY REGULATION 2002 2.19.29.B

12. 63 Work involving direct contact with electrical part (1) Work may be performed involving a person coming into direct contact with an electrical part if the electrical part is— (a) isolated from all sources of electricity; and (b) tested to ensure it is, or otherwise confirmed to be, isolated from all sources of electricity; and (c) if the electrical part is a high voltage electrical part— earthed. ELECTRICAL SAFETY REGULATION 2002 2.19.29.B

13. Safe Isolation of a Supply Test before you touch, this protects you physically, so you can have a good day! Procedure to isolate a Supply 1.Notify all persons likely to be affected by the isolation. 2.Determine the method to isolating the supply. 3.Test the supply availability. 4.Isolate the supply. 5.Danger tag the isolation device. 6.Test that the supply is isolated. 7.Test the testing device. 2.19.29.C

14. 20 Signs on switches and disconnection points (1) This section applies if— (a) a licensed electrical worker is performing electrical work; and (b) to perform the work, the worker has de-energised, or otherwise isolated from electricity, an item of electrical equipment that is the subject of the electrical work or that is near where the electrical work is being performed; and (c) to de-energise, or otherwise isolate, the item of electrical equipment, the licensed electrical worker has operated a device; and (d) while the worker is performing the work, the worker does not have the device under the worker’s sole effective control. (2) The licensed electrical worker must ensure that there is attached to the device, in a prominent position, a warning sign that is suitable in the circumstances, having regard to AS 1319 (Safety signs for the occupational environment). Maximum penalty—40 penalty units. ELECTRICAL SAFETY REGULATION 2002 2.19.29.C

15. Lockout Tags “Out of Service” tags are equipment protection only. “Danger” tags are personal protection. Can only be removed by the person who placed the tag or the principle with written permission. Danger Name Dept Reason Do Not Energize 2.19.29.C

16. Isolating Supplies Fuse Circuit Breaker Remove the fuse wedge Remove the fusible link. Replace the wedge to cover the otherwise exposed terminals. Fit the danger tag. Remove the fusible link from the switchboard area (place it in your pocket). Turn off circuit breaker Fit the danger tag. 2.19.29.B

17. Working with the plug in Remove the plug from the socket before working on an appliance. Only when testing an appliance’s operation should the plug remain connected to a power point. The switch mechanism on a power point only isolates one active conductor. If the polarity is reversed then the mechanism isolates the neutral conductor, leaving an active at the appliance. Always test before you touch. 2.19.29.B

18. Storage Devices Storage devices such as capacitors must be discharged before any work is to be commenced. Devices such as microwave ovens, variable speed drives, switch mode power supplies are considered very dangerous if the capacitor is not discharged. 2.19.29.C

19. The two golden rules Test before you touch, this protects you physically, so you can have a good day! Test your work is electrically safe when completed, tests include insulation resistance, earth continuity, polarity, and visual inspection, this protects you financially.

20. Disconnection of Cables Check the supply is isolated. Make a sketch of the connection showing the terminal positions and cable colours\numbering etc.. Number or label each cable as it is disconnected. Insulate the cable ends, damaged cable lugs or ends should be cut off to be refitted latter. Enclose the cable ends in an appropriate enclosure such as a PVC junction box. Ensure a danger tag is fitted at the point of isolation. Fit a danger tag to the cable end and identify the isolation point. 2.19.29.C

21. The rated supply voltage for a replacement appliance must be the same as the unit it replaces. Determine the circuit current of the appliance being connected. Most appliance plates have voltage and power ratings. The current carrying capacity of the connecting cables needs to be assessed using AS/NZS-3008.1.1 Also check the rating of the Fuse or circuit breaker. Manufacturer Specifications of disconnected & replacement equipment. When replacing any load you should be sure that the new item is suitable with regards to: Speed, Rotation, Power rating, Voltage, Current, Physical size, Environmental conditions & design of replacement, Dust & waterproof, temperature, UV rating, touch proof, life span. 2.19.29.D

22. Electric Shock To receive an electric shock two conditions must be reached 1.Access to electricity Direct contact. Indirect contact ( insulation resistance failure) Insulation Resistance Test. 2.elevated potential of the electricity. Earthing circuit is at zero volts due to the low resistance of the MEN point, therefore if the earthing circuit is kept to very low resistance values the voltage will also stay low. Earth Continuity Test 2.19.29.D

23. Final Tests 1 Visual inspection, is the work as per AS/NZS 3000:2007? 2 Earth continuity test, is the earthing circuit continuous? AS/NZS 3000:  < 0.5 . 3 Insulation resistance test, is the conductors insulation able to contain the operating voltage? AS/NZS 3000:2007 > 1M  4 Polarity, are the outlets correctly connected, are the circuit actives switched? 2.19.29.D

24. Analogue insulation-continuity Tester 2.19.29.D

25. Scale Plate Megohm scale Megohm Selector switch 2.19.29.D

26. Low reading ohm scale Scale Plate Low reading ohm Selector switch 2.19.29.D

27. Scale Plate 500 ohm scale 500 ohm Selector switch 2.19.29.D

28. Battery check scale Battery check Selector switch Always check your batteries before using the meter 2.19.29.D

29. Test Button 2.19.29.D

30. When measuring continuity it is important to adjust your meter to zero ohms before you commence. Ohms zero adjust 2.19.29.D

31. Measuring insulation resistance at 250vDC Megohm Selector switch is set to 250V Megohm scale x ½ i.e needle reading = 5 IR = 5 x ½ = 2.5 M  2.19.29.D

32. Measuring insulation resistance at 500vDC Megohm Selector switch is set to 500V Megohm scale x 1 i.e needle reading = 2.5 IR = 2.5 x 1 = 2.5 M  2.19.29.D

33. Measuring insulation resistance at 1000vDC Megohm Selector switch is set to 1000V Megohm scale x 2 i.e needle reading = 1.25 IR = 1.25 x 2 = 2.5 M  2.19.29.D

34. Instrument set to low reading ohms One lead connected to the earth pin Other lead connected to the metal frame 2.19.29.E

35. Class 2 equipment X

36. Instrument set to 500vdc M  scale One lead connected to the earth pin Other lead connected across active & neutral pin 2.19.29.E

37. X, Wrong Class 2 equipment No earth wire from plugtop 2.19.29.E

38. Lead connected to frame of appliance Correct Class 2 equipment 2.19.29.E

39. AS/NZS 3760 Clause 2.3.3.2 (b). Instrument set to 250vdc MOV 2.19.29.E

40. Circuit integrity Switch off the supply to the circuit. Determine the current draw for the circuit, (name plate). Measure the Resistance of the circuit. Using Ohm’s Law, determined if the current is greater than the rating of the fuse element then investigate the cause. If the circuit is OK, re-energise. 2.19.29.E

41. Reconnection of Cables Never assume the cables are dead, –TEST BEFORE YOU TOUCH Measure the insulation resistance of the cables. Measure the insulation resistance of the replacement article. Reconnect cables as per your disconnection diagram. Test your connections for firmness and visual correctness. Measure the Earth continuity of the earthing circuit. 2.19.29.F

42. Energising supply Only after the visual inspections and safety testing as per AS/NZS 3000:2007 has proven that the circuit is fit for purpose are you to energise the circuit. Remove only your Danger tag. If another worker has their danger tag on the isolated point then you can not energise. If clear: Energise the circuit. Test for the correct and safe operation of the circuit, i.e. rotation, system performance, current draw, voltage, etc. Prepare all your safety and performance documentation. 2.19.29.G

43. Further readings Questions Topic 6 Q1-Q48