EKAS 2.19.30 Flexible cords and plugs to 250 V

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EKAS 2.19.30Flexible cords and plugs to 250 V
UEE31307 Certificate III in Refrigeration and
Air Conditioning Stage 2A Units
UEENEEPOO2B Chris Hungerford Friday, September
11, 2015
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Flexible cords
Heavy Duty
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How is a flexible cord different from other
cables?

• The conductors in a flexible cord are made up of
  many more strands of finer wire than an ordinary
  cable (0.3mm). This allows the cord to flex
  without breaking the conductors.
• The maximum cross-sectional area (CSA) of a
  conductor in a flexible cord is 4mm2.
• Finally, the maximum number of insulated
  conductors (or cores) in a single cord is five.

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Maximum length of flexible cords
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Maximum current rating of flexible cords
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NOTES 1 Where a flexible cord is wound on a
drum, multiply current-carrying capacity by the
appropriate factor, as follows Number of layers
1 2 3 4 Derating factor
0.76 0.58 0.47 0.40 2 Flexible cords
having tinsel conductors with a nominal
cross-sectional area of 0.5 mm2 have a current
carrying capacity of 0.5 A. 3 The
current-carrying capacity is based on a cable
maximum conductor operating temperature of 60C
in order to limit the surface temperatures for
the expected use of such cables. Where flexible
cords are used as fixed wiring, the current
ratings are given in Tables 4 to 15 and 17.
(Refer to Clause 3.3.2). 4 To determine the
three-phase voltage drop, refer to the
appropriate value in Table 46, Table 47 or Table
48. To determine the single-phase voltage drop,
multiply the three-phase value by 1.155.
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Electrical cables
3 Core Earth Circular

• An electrical cable is identified by its
• Conductor material e.g. copper or aluminium
• Conductor size e.g. 1.5mm² CSA
• Insulation material e.g. rubber, glass, PVC
• Number of cable cores e.g. 7/0.50 i.e. 7
  strands of 0.50mm circular diameter
• Voltage grading e.g. 0.6 / 1 KV 250V / 440V
• Sheathing
• Protection

Conductor
Strand
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Steel Wire Armoured SWA
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Ratings of cables

• Voltage rating, all cables have a maximum
  operating voltage. This is directly related to
  the type and thickness of the insulation
  material.
• Temperature rating, table 3.2 AS 3000 2007.
• Cables are NOT rated in Current Carrying
  Capacity. A cable's current carrying capacity is
  determined buy how it is installed as per AS/NZS
  3008.1.1 (Australian).

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Selecting a cord

• Current carrying capacity of the cable.
• Operating conditions
• temperature
• voltage
• installation factors such as in direct sunlight,
  mechanical protection, thermal installation.
• Number of conductors.

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Plugs and sockets

• There are many types of plug tops, the most
  common being the 10A three-pin plug.

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International Protection Numbers
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AS/NZS-30002007 SAA Wiring Rules

• 3.7.2.8 Flexible cords
• Joints shall not be made in flexible cords.
• Exceptions Joint in flexible cords may be made -
• Where used as installation wiring
• By means of suitable cable couplers
• Any flexible cord shall be installed so that
  undue stress on its connections due to a pull on
  the cord is alleviated by a pillar, post, grip,
  tortuous path, or other effective means.
• Knotting of the flexible cord shall not be
  acceptable for this purpose.

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Accessories

• All accessories must be suitable and as per
  Australian standards .
• All accessories must be suitable for the
  application.
• Wide variety of accessories can be accessed via
  suppliers catalogues.

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AExcellent BGood CFair DPoor
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AS/NZS-30002007, SAA Wiring Rules
3.7 ELECTRICAL CONNECTIONS 3.7.1
General Connections between conductors and
between conductors and other electrical equipment
shall provide electrical continuity and adequate
mechanical strength.

• Solder less lugs
• Crimps
• Compression terminals
• Soldered connections

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AS/NZS-30002007 SAA Wiring Rules
3.7.2.2 Preparation for connection The insulation
on a conductor shall not be removed any further
than is necessary to make the connection. For
connections between insulated conductors the
connection shall be insulated to provide a degree
of insulation not inferior to that of the
conductors. Any damaged insulation shall be
reinstated.
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Insulation of conductors

• No
• Masking tape
• packing tape
• sticky tape
• silicon mastic

• Yes
• Electrical insulation tape
• Epoxy kits
• Heat shrink

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Conductor colouringAS/NZS 3000 Table 3.4
Colour
Function
Earth/bonding
Green/yellow
Neutral
Black
Light blue
Active
Red Brown, dark Blue, Grey, White, any colour
other than green/yellow, green, black, yellow or
light blue
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Terminations and connections

• Connections must not be soft soldered before
  compression terminations.
• Must be seated correctly.
• Free of dirt and oxides.
• Use a suitable lug or connector.
• Insulated to the equivalent of the original
  insulation.
• Earth connection must be painted if exposed to
  weather

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AS/NZS-30002007 SAA Wiring Rules
3.7.2.6 Mechanical stress All cables and
conductors shall be installed so that there is no
undue mechanical stress on any connection.
3.7.2.3.1 Loosening of connections Connections
shall be made so that no loosening is likely
because of vibration, alteration of materials or
temperature variations to which the
connections are likely to be subjected in normal
service.
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The eight visual checks recommended are

• Check for obvious damage or defects.
• Check that flexible cords are properly anchored
• Check for any damage to flexible cords.
• Check that maximum load warning labels are
  intact.
• Check that any controls such as switches are in
  working order.
• Check that covers and guards are properly
  secured as intended.
• Check that any safety devices are in good
  working order.
• Check that vents or exhausts are unobstructed.

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Earth Continuity Test

• Any Class I equipment with exposed metal parts
  must have its protective earth checked to ensure
  it is continuous from the earth pin of the plug
  to any exposed metal. The resistance must not be
  greater than 1?.

Instrument Low reading ohmmeter.
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Earth Continuity
Earth Pin To Earth Socket
?1?
What is the value of earth continuity?
Instrument Low reading ohmmeter.
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Earth Continuity Class 1
Earth Pin To Exposed Metal
?1?
What is the value of earth continuity?
Instrument Low reading ohmmeter.
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Insulation Resistance Test

• All equipment must be tested to ensure the
  integrity of the insulation, no electricity must
  be allowed to escape from the conductors or the
  appliance.

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Insulation Resistance Class 1
Switch ON
Active Neutral To Exposed Metal
?1M?
?1?
Q What is the value of insulation resistance?
Megohmmeter
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Insulation Resistance Class 2
Switch ON
Active Neutral To Exposed Metal
?1M?
?1M?
?1?
Q What is the value of insulation resistance?
Megohmmeter
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Insulation Resistance extension lead
Active Neutral To Earth Pin
?1M?
?1?
Q What is the value of insulation resistance?
Megohmmeter
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Polarity
Active Pin To Active Socket
low?
?1?
What is the value of continuity?
Instrument Low reading ohmmeter.
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Polarity
Neutral Pin To Neutral Socket
?1M?
low?
?1?
What is the value of continuity?
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Instrument Low reading ohmmeter.
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Is this correct?
What should the voltage be?
V2?
240v
V1 240v V2 240v V3 0v
V3?
240v
V1?
0v
Is this correct?
0v
Reversed polarity A-N
0v
0v
No Supply
Is this correct?
Is this correct?
0v
240v
240v
0v
240v
240v
Correct
Reversed polarity A-E
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Minimum records that should be completed and
maintained

• A record of the inspection and test results.
• A record of faulty electrical equipment (has it
  been repaired or destroyed).

Date of inspection Appliance Visual inspection Earth continuity W Insulation resistance MW Polaritya Correct RCD test current 30 MA trip time Milliseconds 0h 180h Test butt RCD test current 30 MA trip time Milliseconds 0h 180h Test butt RCD test current 30 MA trip time Milliseconds 0h 180h Test butt
2/7/09 Refrigerator ( LG model R100020 Serial 1004039832) O.K 0.3 75M N/A N/A N/A N/A
2/7/09 Safetypac (Clipsal mod 56B, serial 9987987) o.K. 0.8 187M a 22 18 a
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Energising supply

• Only after the visual inspections and safety
  testing as per AS/NZS 30002007 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.

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