Transcript Slide 1

EKAS 2.19.30
Flexible cords and plugs to 250 V
UEE31307 Certificate III in
Refrigeration and Air Conditioning
Stage 2A
Units: UEENEEPOO2B
Chris Hungerford
Saturday, July 18, 2015
Flexible cords
Ordinary Duty
Light Duty
2.19.30.A
Heavy Duty
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
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 60°C 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.
Electrical cables
3 Core & Earth Circular
An electrical cable is identified by its:
1.
2.
3.
4.
5.
6.
7.
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
Strand
2.19.30.A
Conductor
Steel Wire Armoured SWA
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).
2.19.30.A
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
AS/NZS-3000:2007 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 (a) Where used as installation wiring
(b) 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.
2.19.30.C
2.19.30.C
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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A=Excellent B=Good C=Fair D=Poor
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AS/NZS-3000:2007, 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
2.19.30.C
AS/NZS-3000:2007 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
Yes
• Electrical
insulation tape
• Epoxy kits
• Heat shrink
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No
• Masking tape
• packing tape
• sticky tape
• silicon mastic
Conductor colouring
AS/NZS 3000 Table 3.4
Earth/bonding
Colour
Green/yellow
Neutral
Black
Function
Active
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Light blue
Red Brown, dark Blue, Grey, White, any colour
other than green/yellow, green, black, yellow or
light blue
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
2.19.30.C
AS/NZS-3000:2007 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:
1.
2.
3.
4.
5.
6.
7.
8.
2.19.30.D
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.
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 1Ω.
Instrument Low reading ohmmeter.
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Earth Continuity
Earth Pin
To
Earth Socket
1
What is the value of earth continuity?
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Instrument Low reading ohmmeter.
Earth Continuity “Class 1”
Earth Pin
To
Exposed Metal
1
What is the value of earth continuity?
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Instrument Low reading ohmmeter.
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
1M
1

Exposed Metal
Q What is the value of insulation resistance?
2.19.30.D
Megohmmeter
Insulation Resistance “Class 2”
Switch ON
Active & Neutral
To
1M
1M
1

Exposed Metal
Q What is the value of insulation resistance?
2.19.30.D
Megohmmeter
Insulation Resistance “extension
lead”
Active & Neutral
To
Earth Pin 1M
1M
1

Q What is the value of insulation resistance?
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Megohmmeter
Polarity
Active Pin
To
Active Socket
low
1
What is the value of continuity?
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Instrument Low reading ohmmeter.
Polarity
Neutral Pin
To
Neutral Socket
low
1M
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?
V
2
=
?
V1 240v
V2 240v
V3 0v
240v
V
3
=
?
V
1
=
?
240v
0v
Is this correct?
0v
Reversed polarity A-N
0v
0v
No Supply
Is this correct?
Is this correct?
0v
240v
0v
240v
Correct
240v
240v
Reversed polarity A-E
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

Insulation
resistance
a
RCD test current
30 MA trip time
Milliseconds
0h
180h Test butt
Polarity
= Correct
M
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 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.
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