refrigeration electrical wiring -...

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HVAC & Refrigeration – Ultimo 2007Refrigeration Electrical Wiring

Refrigeration Electrical WiringModule No: NREW

Contents: Page No

Refrigeration Electrical Wiring.................................................................................. 1Section No: 1 Electrical Isolation & Safety........................................................... 3

Review Questions: Section No: 1 ............................................................. 14Section No: 2 Statutory Requirements and Standards.......................................... 17

Review Questions: Section No: 2 ............................................................. 20Section No: 3 Cables (Building &TPS)............................................................... 22

Review Questions: Section No: 3 ............................................................. 27Section No: 4 MIMS, SWA & Armoured Cables................................................ 29

Review Questions: Section No: 4 ............................................................. 31Section No: 5 Data Cables .................................................................................. 32

Review Questions: Section No: 5 ............................................................. 33Section No: 6 Flexible Cables............................................................................. 34

Review Questions: Section No: 6 ............................................................. 38Section No: 7 Appropriate Fixing Devices.......................................................... 40

Review Questions: Section No: 7 ............................................................. 43Section No: 8 Competency Assessments............................................................. 44

UTE NES208A:........................................................................................... 45UTE NES 209A:.......................................................................................... 46UTE NES 209A:.......................................................................................... 47UTE NES 210A:.......................................................................................... 48

Answers: Review Questions: ............................................................................... 49

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HVAC & Refrigeration, Ultimo 2006Refrigeration Electrical Wiring NREW

2

Refrigeration Electrical WiringStudent Resource Package NREW

Delivery: Competence in this training program can be achieved through either a formal education setting by completing the attached student resource packages or in the workplace environment.

Prerequisites:

The following resource packages or equivalent are prerequisites:

� Occupational Health & Safety (7793T)� Refrigeration Electrical 1 & 2.

Recognition of Prior Learning:

The student/ candidate may be granted recognition of prior learning if the evidence presented is authentic and valid which covers the content as laid out in this package.

Competencies:

� UTE NES208A: Disconnect & Reconnect fixed wired electrical equipment (up to 1000Volts).

� UTE NES 209A: Attach flexible cords and plugs to electrical equipment connected to 240 volt supply

� UTE NES 210A: Attach flexible cords and plugs to electrical equipment connected to a supply up 1000 volts AC ( Three phase 415)

Suggested Resources:

Jenneson, JR., 1995, Electrical Principles for Electrical Trades, McGraw Hill, Sydney. Phillips, P., 1996, Electrical Principles 1, Thomas Nelson, Melbourne. Phillips, P., 1996, Electrical Principles 2, Thomas Nelson, Melbourne. Pethebridge, K., Williams, W., Australian Electrical Wiring, Sydney. AS/NZS 3000 & 3008 Wiring Rules. Australian Refrigeration and Air Conditioning Volume 1 & 2.

The writers of this resource package would like to recognise the positive support of all the HVAC & Refrigeration teaching staff at Ultimo College of TAFE for their valued assistance.

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Section No: 1 Electrical Isolation & SafetyPurpose:The aim of this section is to provide you with the underpinning knowledge and skills to work safely when isolating and reconnecting electrical circuits to enable component replacement, service and or maintenance on refrigeration and or air conditioning plant and equipment.

Reason for StudyAs a consequence of the law a refrigeration mechanic is limited in the work they are allowed to undertake on the electrical reticulation system. The law and the procedures you must follow are explained in this package.

Electrical Safety:The legal requirements of all wiring systems are designed to maintain the highest practical safety standards in electrical wiring applications and these requirements are detailed in the current AS/NZS 3000 & 3008 Wiring Rules. These rules and regulations are designed to:

Protect persons, livestock and property from electric shock, fire, physical injury and hazards that may arise from an electrical installation that is used with responsible care and with due regard to the intended purpose of the electrical installation.

The refrigeration / air conditioning technician has the responsibility to ensure that he or she maintains a duty of care, which means that all safety precautions have been implemented to ensure their personal safety, the safety of others and that the plant and equipment operate in accordance with all OH&S regulations, relevant codes, wiring rules and legislative requirements.

Safety measures against electric shock:While the human body has a fairly high resistance, current will flow through the human tissues if contact is made between two electrical points of different electrical potentials.e.g. Active and neutral, or active and earth, or touching both ends of a cut neutral conductor or between any two phases.The path the current takes through the human body will have a huge impact on thephysiological effect of current flow. The amount of current flow in the body will depend on the potential difference (supply voltage) and the natural resistance of the particular human.Electric shock usually does not kill at once, but may stun the victim, stop the breathing and effect, the heart. Any delay in rescue and resuscitation may be fatal:“every second counts”.

There are three general safety measures and they are as follows: SAFE PRACTICES SAFE EQUIPMENT KNOWLEDGE OF HOW THE EQUIPMENT WORKS.

Remember:

Current=Voltage Resistance

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The Electrical Supply System.

The electrical supply system used in Australia has three parts;

The Production.Most of the EMF produced in NSW is generated by electromagnetic induction usually by steam driven alternators.

The Distribution. “see map below”

The Consumers.This is the end of the electrical system where the energy is converted into other forms of energy.

Consumer Electrical Systems

The electrical supply is delivered to the consumer via cables called ‘consumer mains’. The mains are connected to the Main Switchboard, which controls distribution of the electricity to Sub-boards via cabling called ‘sub-mains’.The Switchboards contain the following items, none of which the refrigeration mechanic is allowed to work on.

Components of a Commercial Switchboard and Control Panel.

Main Switch. The main switch (S/W), offers no protection for the circuits, its purpose is to isolate the internal wiring (busbar), of the s/w. board. It should be rated at the calculated maximum demand of the board.

Busbar.

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This is made from solid copper bar, which is arranged so that the three-phase supply can be distributed equally to the three phase and single phase circuit breakers.

Neutral Link. This has the main neutral connected to it and it is the point of attachment for the individual circuit’s neutrals, each circuit must have its own terminal.

Earth Link. The main earth connection and point of attachment for the individual circuits, each circuit should have its own terminal.

Cable Trays. These are a means of keeping the external wiring neat and tidy inside the switchboard, while running between the outside and the protective device or control device.

Labelling. All s/w boards, sub-boards, circuits, main switches and connection links must be labelled in accordance with AS3000.

Fuses, circuit breakers and contactors will be dealt with separately.

Reticulation within a single installation:The complete electrical installation in a reticulation system consists of:

Consumer mains Main switch board Sub-circuits Sub-mains Sub-distribution board Appliances or loads.

All the individual circuits must have their own protecting device ie; (fuse/circuit breaker) from the circuit origin. Note: attached block diagram Fig. 3.

Single Phase Electrical Systems

Single phase electrical systems:

Single phase electrical systems consist of: Incoming supply Main switch Main neutral link Circuit breaker or fuse (protective device) Circuit conductors (cables) Load (plant and associated equipment)

Conductors: There are two conductors: active, neutral and the earth wire.

Single phase supply: note Fig 1

The earth cable is referred to as a wire because traditionally it was uninsulated which gives it the classification of a wire, whereas a conductor is insulated.

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Fig 1.

Multiple Earth Neutral System (MEN)The MEN system is used to maintain the neutral conductor at earth potential. This is done by connecting the main earthing conductors together with the main neutral link at the main switchboard. (Fig 1) Circuit Identification: The circuit in an electrical installation comprises of a power source,

circuit conductors and a load as shown in Fig. 2.Each individual circuit is separated by its own individual protective device, for example the light and power circuits have their own fuse / circuit breaker.

Fig. 2 Protective and isolating devices:

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Most refrigeration and air conditioning units are fitted with overloads of either external or internal type. However the whole circuit must also be protected against failure of the unit or equipment overloads. A common cause of fires in buildings is the overheating of building or house electrical wiring in ceilings or walls due to excessive current draw and therefore protection for the wiring system needs to be taken into account.

Every active conductor of a final sub-circuit must be protected by a device suitable for disconnecting the power from the circuit in the event of excessive current being drawn. This protection may be in the form of Re-Wireable Fuses, High Rupturing Capacity Fuses (HRC) or Over-Current Circuit Breakers.

Fuse: Re-wireable; The base is rigidly fixed, while the wedge can be removed from the base to allow easy and safe replacement of the fuse element. Fuses are rated by current the fuse element will carry continuously without over heating. Disadvantages: include relatively slow response compared to the HRC fuse and circuit breaker and lack of control on the size of the fuse element.

The current AS/NZS 3000 states in the clause section:Clause 1.4.55.Fuse. A device for protecting a circuit against damage from excessive current flowing in it by opening the circuit on the melting of the fuse-element by such excessive current.

High Rupturing Capacity (HRC); The HRC fuse has its fuse element enclosed in a ceramic body filled with arc suppressing silicon powder.This body confines the heat energy created by the melting of fuse element completely within the container. The fuse element is made of silver, which makes the fuse far more accurate in its operation.

The HRC fuse has a greater reliability in its speed in response compared with that of the re-wireable fuse. The HRC fuse has the ability to open circuit in less than one hundredth of a second under short circuit conditions and is used extensively as protection where high fault currents may occur.

Note: the advantages of a HRC fuse are its speed of response and accuracy under high fault currents.

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Circuit Breaker: The circuit breaker will open or trip under fault conditions, but does not require replacement of parts (fuse element). While being responsive to over-current, they also act (in a limited way) as a switching device for the circuit.

Ideal requirements for a circuit breaker:� It should be responsive to ambient temperature that

is the time required to trip the circuit breaker under over-current conditions automatically adjusts itself with the changing surrounding temperatures.

� It should trip instantly when passing ten times its rated current.

� It should have an inverse time characteristic: As excess current in the circuit breaker increases, the time taken for the circuit breaker to trip should decrease.

Types of circuit breakers:

Thermal circuit breaker: This type of circuit breaker relies on the operation of a thermal strip to trip the breaker. They are slow to respond normally used on motor circuits.

Magnetic circuit breaker: This type uses the magnetic field created by the current in the circuit breaker to operate the trip mechanism in the circuit breaker. These are used everywhere as the are quick to respond to fault current.

Low voltage thermal magnetic circuit breaker: Uses a combination of above and is the most common used in Australia

Below is a photograph of the internal details of a 10 ampere DIN rail mounted thermal-magnetic miniature circuit breaker. Circuit breakers such as this are the most common style in modern domestic consumer units and commercial electrical distribution boards. Unfortunately, while the size and shape of the opening in the front and its elevation from the rail are standardized, the arrangements for busbar connections are not, so installers need to take care that the chosen breaker fits the bus bar in a particular board.

Two pole miniature C/B

1. Actuator lever - used to manually trip and reset the circuit breaker. Also indicates the status of the circuit breaker (On or Off/tripped). Most breakers are designed so they can still trip even if the lever is held or locked in the on position. This is sometimes referred to as "free trip" or "positive trip" operation.

2. Actuator mechanism - forces the contacts together or apart.

3. Contacts - Allow current to flow when touching and break the flow of current when moved apart.

4. Terminals 5. Bimetallic strip 6. Calibration screw - allows the manufacturer

to precisely adjust the trip current of the device after assembly.

7. Solenoid 8. Arc divider / extinguisher

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Circuit Breaker Rating.

Circuit Breakers’ use a rating similar to the transformers in as much as the do not consume energy unless there is a fault on the circuit. They have a Voltage rating and a maximum current rating, they also a kA rating which is an indicator of how much short term over current they can absorb before they trip. Circuit breakers that do not have the kA rating are only suitable for power and light circuits. Circuit breakers with a 4kA rating can be used to protect the wiring to a small split system.Ratings greater than 6kA are needed for larger systems, they will allow the compressor to start direct on line (DOL) without causing the circuit breaker to trip.

A major advantage of circuit breakers over fuses is that they cannot be tampered with and so have reliable and consistent operation. Most fuses however may be loaded to many times their rated current carrying capacity thus decreasing their effectiveness as a protective device. Also modern circuit breakers are “TRIP FREE” which means they cannot be closed under fault conditions.

Earth Leakage Circuit Breaker

An earth leakage circuit breaker (ELCB) is a device with two earth terminals used to directly detect currents leaking to earth from an installation and cut the power. They were mainly used on Australian circuit pre 1966. By having the assumption of the presence of current in the earth line, it means there is any leaking current from the main incoming live cable, thus the power has to be cut off to ensure the safety. State of ELCB when it cuts the power is called tripped. Every time the ELCB tripped, we can reset it back (connect back the power line) by resetting the trip button.

They cannot detect earth faults that do not go through the earthing system. They do not allow a system to be easily split into multiple sections with independent

fault protection, due to the fact that earthing systems are usually bonded to things like pipework.

They may be tripped by external voltages on something connected to the earthing system such as metal pipes, or a MEN system.

They introduce additional resistance and an additional point of failure into the earthing system.

Due to the number of problems, they’ve almost been replaced by Residual Current Devices, (RCD) (except in very old installations)..

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Residual Current Device (RCD)Clause 1.4.3. Residual current device (RCD). A device intended to isolate supply to protect the protected circuits, socket-outlets or electrical equipment in the event of current flow to earth which exceeds a predetermined value.

A residual current device (RCD), or residual current circuit breaker (RCCB), is an electrical wiring device that disconnects a circuit whenever it detects that the flow of current is not balanced between the phase ("hot") conductor and the neutral conductor. The presumption is that such an imbalance may represent current leakage through the body of a person who is grounded and accidentally touching the energized part of the circuit. A shock, possibly lethal, is likely to result from these conditions; RCDs are designed to disconnectquickly enough to prevent such shocks.

Purpose and operation

RCDs operate by measuring the current balance between two conductors using a differential current transformer, and opening the device's contacts if there is a balance fault (i.e., a difference in current between the phase conductor and the neutral conductor). More generally (single phase, three phase, etc.) RCDs operate by detecting a nonzero sum of currents, i.e. the current in the "live" (phase) conductor plus that in the "neutral" conductor must equal zero (within some small tolerance), otherwise there is a leakage of current to somewhere else (to earth/ground, or to another circuit, etc.).

They do not protect if the fault current is between active and neutral, unless its current rating is excessed.

The incoming supply active and the grounded neutral conductors are connected to the terminals at (1) and the outgoing load conductors are connected to the terminals at (2). The earth is connected through from supply to load uninterrupted.

When the reset button (3), is pressed the contacts (4 and hidden behind (5) close, allowing current to pass. The solenoid (5) keeps the contacts closed when the reset button is released.

The sense coil (6) is a differential current transformer which surrounds (but is not electrically connected to) the live and neutral conductors. In normal operation, all the current flowing down the live conductor returns up the neutral conductor. The currents in the two conductors are therefore equal and opposite and cancel each other out.

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It is normal in Australia to fit a Residual Current Breaker with Overload. (RCBO is a combination of an RCD and a miniature circuit breaker (MCB)). This will protect an individual circuit for both earth leakage and overload.

The RCBO is installed in the consumer’s Distribution Board in what is known as a split load configuration where one group of circuits is just on the main switch (circuits that have small leakage devices (Refrigerators)). and another group on RCBOs (power points and light circuit).

RCDs and CBs are not circuit isolators, they are protective devices.

Isolation devices:The primary function of an isolating device in an electrical circuit is to manually disconnect a ability to remain waterproof. Check the “IP’ rating before using an isolator outside.

� Lockable isolator: (required where the isolator is to be tamperproof).� Control isolators: (the normal type isolator).

AS/NZS 3000 Wiring Rules:The current AS/NZS 3000 states:

� Isolation: Clause 2.8.2.1 – Electrical installations shall include all devices for isolation and switching necessary to enable operations, repairs and maintenance work to be carried out with safety.

� Isolation: Clause 2.8.3.5 – every motor shall be provided with an isolation switch that isolates the motor from the supply.

It must be emphasised the necessity of these rules to govern and protect the safety of the circuit, plant, equipment, those who are involved and the general public.

Isolation, Testing and Tagging

Lock and tag or lock-out tag-out is a safety procedure which is used in industry to ensure that dangerous machines are properly shut off and not started up again prior to the completion of maintenance or servicing work. It requires that hazardous energy sources be "isolated and rendered inoperative" before any repair procedure is started.

The procedure requires that a tag be affixed to the locked device indicating that it should not be turned on.

A lock selected by color, shape or size (e.g. red padlock) is used to designate a standard safety device, locking and securing hazardous energy. No two keys or locks should ever be the same. A person's lock and tag must not be removed by anyone other than the individual who installed the lock and tag unless removal is accomplished under the direction of the employer.

Employer procedures and training for such removal must have been developed, documented and incorporated into the employer's energy control program

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All electrical equipment must be correctly isolated when work is to be undertaken on the equipment for the following reasons:

� To prevent electric shock.� In case of fire, flood, etc.� To prevent physical injury� To prevent unauthorised use of equipment.

It should be noted that when isolating a circuit, testing needs to be done to ensure the isolation is effective and locking and or danger tagging needs to be carried out so that the circuit remains isolated. (Danger Tag Fig. 7)

Note: isolation Danger Tag must only be removed by the person who originally isolated and tagged it, or by authorised personnel

Fig. 7

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Electrical Test Equipment:There are a number of electrical circuit test instruments and they can either come in analogue or digital: Types of meters:

Recommended volt meter (Analogue type) Test lamps, tests 240 or 415 volts. Combi-check LED Indicator, combination of voltage and continuity. Multi-meters can be used to check various voltages, resistances and continuity. Clamp-On (ampere meter) comes with a number of functions such as: amps, voltage

and resistance.

Procedure to Isolate, Test and Tag an Electrical Circuit:The following details the required steps to be taken when isolating an electrical circuit.

1. Notify owner, manager of intension to isolate the circuit.2. Locate the isolating device.3. Test the circuit to verify tester operation and that the circuit is live.4. Isolate the circuit.5. Test circuit to confirm power is no longer present.6. Check the test instrument to verify that it still operates.7. Lock and tag the isolation device or,8. Remove the fuse carrier and take out the fusible link (if a fuse).9. Replace the fuse carrier.10. Connect a short circuit between the circuit conductors and the earth wire.

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Review Questions: Section No: 1

1. An electrical circuit starts at the:(a) circuit conductors(b) load(c) earth(d) supply or source. ( )

2. In the MEN system of earthing the two cables that are joined together at the main switch are:(a) the active and earth(b) the active and neutral(c) the neutral and earth(d) none of the above. ( )

3. Isolating switches are used in electrical circuits to:(a) manually separate equipment from the active conductors(b) interrupt the supply automatically(c) terminate circuit wiring(d) start motors. ( )

4. When isolating an electrical circuit, the fuse should be removed from its base, danger tagged and then:(a) be left lying in the switch board(b) have the element removed and the carrier replaced in the fuse base(c) be taken away by the person isolating the circuit(d) be thrown away. ( )

5. A danger tag should only be removed from an electrical isolator by:(a) a licensed electrician (b) an operator(c) the person who placed it there(d) the owner of the building. ( )

6. Circuit breakers and fuses are used in electrical circuits to:(a) indicate current(b) isolate the supply(c) interrupt the active line automatically if excessive current flows(d) make the MEN connection. ( )

7. The fuse element of an HRC fuse is usually made of:(a) copper(b) tin lead(c) silver(d) brass. ( )

8. An isolating switch connected in the supply to an electrical installation is called a:(a) knife switch(b) supply isolator(c) main switch(d) isolator. ( )

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9. List three electrical testing meters: (a)

(b)

(c)

10. Identify the protection devices as show below:

(a) (b) (c)

11. Identify each part of the wiring diagram below:

(a) (e)

(b) (f)

(c) (g)

(d) (h)

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12. Describe how the thermal circuit breaker operates:

13. What are the two main advantages an HRC fuse has over a rewireable fuse?

14. There are two devices used for human protection, list both of them:

15. The installation of electrical systems and there circuits are governed by:

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Section No: 2 Statutory Requirements and StandardsPurpose:The aim of this section is to provide you with an understanding of the legal requirements and the required skills to enable referencing of AS/NZS 3000-2000 and AS/NZS 3008 Wiring rules and its terminology.

Reason for StudyAs a consequence of the law a refrigeration mechanic is limited in the work they are allowed to undertake on the electrical reticulation system. The law and the procedures you must follow are explained in this package.

Legal Requirements:The complete installation of refrigeration / air conditioning system needs to conform to a number of codes and regulations in this section we will cover the AS/NZS 3000 Wiring Rules. These rules are laid out to provide a minimum standard that will ensure the maximum safety within the installation and the current AS/NZS 3000 - 2000 covers a minimum rating for various installation situations.

The contracted installation of any electrical wiring system must be done by a licensed electrician who is operating under a current contractor licence as issued by the Department of Fair Trading.

A licensed Refrigeration / Air Conditioning technician is allowed to disconnect and reconnect directly associated electrical components during normal service work. However, if there are minor wiring alterations needed and as long as it meets with the current AS/NZS 3000-3008 Wiring Rules the service technician can make such alterations. It should be noted that a refrigeration / air conditioning technician cannot install the electrical wiring systems unless they hold the current electrical supervisors licence.

Using AS/NZS 3000 – 2000 & AS/NZS 3008 Wiring Rules:To become competent in the use of the electrical wiring standards you should make yourself familiar with the following sections:

General Introduction and Definitions (AS/NZS 3000-2000)Example:

� The term “Active” on page 13, Clause 1.4.4. Any conductor which is maintained at a difference of potential from the neutral or earthed conductor. In a system which does not include a neutral or earthed conductor, all conductors shall be considered to be active conductors.

� The term “Consumer Mains” on page 17, Clause 1.4.30. Those conductors

between the point of supply and the main switch board.

� The term “Appliance” on page 14, Clause 1.4.6. Appliance – a consumer device, other than a lamp, in which electricity is converted into heat, motion or any other form of energy, or substantially changed in its electrical character.

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Using the AS/NZS 3000 – 2000 Wiring Rules:

Contents SectionExample: What colours are expressly prohibited for use with current carrying

conductors?

Method: Using (AS/NZS 3000 Wiring Rules)

� Refer to the contents section and locate the heading “Identification”Section 3. Refers to page 87.and clause 3.8.1 Insulation conductors shall be identified by colour given in Table 3.5 to indicate their intended colour.

Table 3.5 Colours of cables:- Earth Green / yellow (recommended) Green (alternative)

Index SectionThe index section is an alternative and the use of a key word is another method of finding relevant information.

Method: Using (AS/NZS 3000 Wiring Rules)

Example 1: What core colours are expressly prohibited for use with current carrying conductors?

Using the index, select a key word from the question (Core Identification) find the entry under this word. In this example the entry is core identification which identifies clause 3.8.1 page 87 : Insulation conductors shall be identified by colour given in Table 3.5 to indicate their intended colour.

Table 3.5 Colours of cables:- Earth Green / yellow (recommended) Green (alternative)

Example 2: What are the general wiring requirements for the installation of electrical equipment for a refrigerated coolroom?

Using the index, select a key word from the question (RefrigeratedCoolroom) find the entry under this word. In this example the entry is selection and wiring systems which identifies clause 7.4.4.2 page 193, move down to wiring systems general clause 7.4.4.2.1 which states:

The wiring system used in a refrigerated room shall be of a type which:

(a) Will not be affected by the operating temperature of the room; and

(b) Does not provide pockets or channels in which moisture might accumulate or through which it might pass into electrical equipment.

Terminology:The following indicates terms that are used in the AS/NZS 3000 - 2000 that are important to prevent any confusion in the identification of components or materials.

Common term: Correct term:

Wire Cable or CordPower Point General Purpose Outlet (GPO)Light Fitting LuminaireLight Socket Batten Holder.J Box Junction Box

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AS/NZS – 3008 Wiring Rules (Cable Sizes):

Cross Sectional area: for a given conductor material and length, the resistance of a conductor in inversely proportional to the cross sectional area (CSA). That is, if the CSA is doubled, than the resistance is halved. The CSA of a cable will ultimately determine its maximum current rating, but other factors such as what the cable runs through will also contribute to its rating, i.e. run in conduit, buried underground or covered by thermal insulation in a ceiling space.

Refer to AS/NZS - 3008:

1. A three core thermoplastic sheathed (TPS) cable is to be run in free air, clipped direct to the wall and needs to carry 20A for a single phase load protected by a circuit breaker. Determine the cable size required and its current rating?

� Refer to the contents section of AS/NZS 3008, Section 3 Types of cables page 16. Clause: 3.3.1 sheathed and unsheathed thermoplastic cables.

� Clause 3.3.1.2 sates: “The method of installation” The current - carrying capacity of a given cable depends on the method of installation. Tables 2(1) to 2(4) provide a schedule of the installation methods applicable to sheathed and unsheathed thermoplastic cables.

� Table 2 (1) Item 13, column 4 refers to tables 12 and 13.

� Table 12 under unenclosed, touching and circuit breaker: indicates 2.5mm2 cable with a current rating of 22 amperes.

Termination and connection of electrical cables:

The current edition of AS/NZS 3000 -2000 states: under Clause No: 4.11. Electrical equipment may be connected to the electrical installation wiring by one of the following methods:

(a) Direct connection: meaning that the fixed wiring will be directly connected to the terminals provided on the electrical equipment.

(b) By socket – outlet: The fixed wiring of the electrical installation shall terminate at a suitable socket – outlet, the wiring to the electrical equipment being continued by means of a plug and flexible cord or cable.

(c) By connecting device: The fixed wiring shall terminate at: - a socket – outlet complying with AS/NZS 3000 - 2000- a suitable junction box - a suitable outlet- any other appropriate connecting

device.

Common terminating devices:� Single screw connector � Double screw connector� Solder less lugs (Ross Courtney)� Crimp lugs (insulated or uninsulated)� Bolt connections� Tunnel or screw type connector� Solder lugs.

Note: The joint must not weaken the systems protection against mechanical damage, fire, electric shock, chemical deterioration or any other hazards.

All main earth connections up to 16mm2 must be soldered.

The correct joining connections and appropriate tools such as soldering iron, hand crimping tool ratchet-type hand crimping tool and crimp tool for solderless lug should be used to comply with the standards.

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1. The correct term for a light fitting is a::

(a) Luminaire(b) Batten holder(c) Ceiling rose(d) lamp ( )

2 Electricians have a legal responsibility to ensure that::

(a) Power is always available(b) The switch board is locked(c) They install wiring systems that conform with AS/NZS 3000(d) They purchase the AS 3000 Wiring Rules. ( )

3. If the cross sectional area of a conductor is increased its current rating will?(a) Decrease (b) Increase(c) Remain unchanged(d) Double ( )

4. All electrical circuit starts at the:(a) Circuit conductors(b) Load(c) Earth(d) Supply source. ( )

5. The scope and application or AS/NZS 3000 requires that:(a) All electrical installations adhere to the safety requirements of

AS/NZS 3000(b) The supply authorities make AS /NZS3000 available free of charge(c) It be compulsory reading for all trade students(d) Electricians to know all the rules ( )

Using AS/NZS 3000. Determine the answers to the following questions. Also include appropriate Clause or Table number from AS/NZS 3000 & 3008 which covers each question.

6. What are the requirements for the installation of duct heaters?

Clause No:

7. What is the CSA of a three core TPS cable installed in free air and connected to a three phase supply; if the current carrying capacity is 35 amps, protected by a circuit breaker; quote the clause and table numbers in your answer:

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8. From the AS/NZS 3000 define the definition of the following terms and state the clause number:

Cable:

Consumer mains:

Earthed:

Appliance:

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Section No: 3 Cables (Building &TPS)Purpose:

The aim of this section is to provide you with the knowledge and skills to identify the structure, colour coding, applications and termination of building and TPS cables used in the refrigeration / air conditioning and electrical industries.

Reason for StudyBuilding Wire is the most common type of cable used in the HAVC industry.

Cable Definition:An insulated conductor (solid or stranded) or two or more such conductors laid together with or without fillings, reinforcements or protective coverings.

1. Building Wire: Single insulated cable designed for use with low to medium voltages, made from relatively course wire strands (compared to flexible) and commonly used on light, power and control circuits.

Colour Codes: Building wire is available in a number of various colours; that is:

� Red, blue, white, brown or violet can be used as an active conductor.� Black is neutral� Green and yellow (earth only).

Cable identification of building wire: Building wire can be identified by:� Size and number or strands� Single insulation� Labelling on cable or drum.

Cable Size: The size of a cable is expressed as the total cross sectional area of the conductor in square millimetres. Cables of 2.5mm2 and under are available with one single strand conductor, or with seven strands. Copper cables over 2.5 mm2 in area must be stranded when using building wire. The most common sizes of building wire are shown in Table No: 1.

Area (mm2) Strands/diameter of each strand1 1/1. 13

1.5 1/1. 381.5 7/0. 502.5 1/1. 782.5 7/0. 674 7/0. 856 7/1. 04

10 7/1. 3516 7/1. 70

Table No: 1

Enclosure of Cables: In most low to medium voltage applications, building wires must be enclosed in a conduit or other protection system as the insulation is not adequate protection against mechanical damage. An alternative form of protection is cable toughing.

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Practical Assessment No: 1

Installing Building Wire in conduit: Procedure:

� Using the layout in Fig. 1 and the components list, obtain the necessary conduit sections, mounting block, junction boxes, cable, and the essential saddles / screws to mount all the components and fittings to the training board.

� Assemble the conduit, mounting block and junction boxes as in Fig. 1 and attach them with saddles and screws.

� Install the cables in the conduit by referring to Fig, 2 making sure that the insulation of the cables is not damaged during this process.

� With reference to Fig. 2 connect the batten holders and light switch.

� Note: If single cable is being terminated, both stranded and solid core conductors should have the exposed conductor doubled over to provide a good area for the clamping screw in the terminal to grip.

� If two wires are joined in one terminal , such as where the black (neutral) cable enters and leaves the lamp holder, the conductors should be twisted together to give the maximum surface area for grip.

� The cable insulation should extend to the entry of the terminal and should not enter the terminal. It is essential that the terminal screw makes contact with the conductor and not the insulation.

Testing Circuit before Connection to Supply Voltage:Using a resistance tester with no electrical connection, check the following:

- resistance between the active and neutral- resistance between active and earth- resistance between neutral and earth

Note: To conform with AS/NZ 3000, you should obtain a resistance reading greater than 1M ohm.

Components and Materials List:� Training (mounting board)� Two batten holders� One standard mounting block� One standard plate and switch� Three junction boxes� 1000 mm red 1mm2 (1/1.3) building wire� 1500 mm black 1mm2 (1/1.3) building wire� 1500 mm white 1mm2 (1/1.3) building wire� 1500 mm earth wire (yellow / green 2.5 mm2 (7/0.67).

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2. Thermoplastic Sheathed Cables (TPS)A cable which has an insulated core or cores, that is surrounded by an outer layer or sheath of insulation is referred to as a sheathed or doubled insulated cable.TPS cable is available in single core or several insulated cores as well as two or more insulated cores with an earthing conductor. Figures 3 & 4 illustrate some of the various types that are available.

Sheathing Colours:� White (most common)� Orange (usually circular)� Grey� Black� Red (fire systems)� Blue (instrumentation)

Current Rating:The term current rating of a cable relates to the maximum continuous current that is permitted to carry under normal operating conditions. The current rating for cables for various operating conditions is listed in Section 3 of AS/NZ 3008.

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Practical Assessment No: 2 Wiring GPO’s

Procedure:� Using the layout in Fig. 5 which shows the job in which you have to complete.

Obtain the necessary equipment using the diagram as a guide.

� Note: you will only need short lengths of 2.5mm2 twin and earth TPS cable.

Testing Circuit before Connection to Supply Voltage:Using a resistance tester check the following:

- resistance between the active and neutral- resistance between active and earth- resistance between neutral and earth

Note: To conform with AS/NZ 3000, you should obtain a resistance reading greater than 1M ohm.

Thermoplastic Sheathed Cable CircuitFig. 5

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1. PVC insulated cables are generally rated in terms of the current they can carry as well as their:

(a) voltage rating(b) temperature rating(c) voltage and temperature rating(d) physical rating ( )

2. The number of strands of copper wire used in 2.5mm2 (7/0.67) building wire is: (a) one (b) seven (c) 19 (d) 67 ( )

3. In most applications, building wire is enclosed in conduit to prevent:(a) ingress of moisture(b) deterioration of the insulation(c) mechanical damage(d) explosion ( )

4. All earthing conductors should be coloured:(a) green(b) yellow(c) green/yellow combination(d) red ( )

5. PVC insulated cables are known as:(a) building wire(b) single doubled insulated(c) thermoplastic sheathed cable(d) bare conductors ( )

6. The sheath colour of flat TPS cables are generally:(a) orange(b) red(c) white(d) blue ( )

7. Thermoplastic sheathed cables are available in two shapes. They are:(a) flat and twin(b) TPS and SDI(c) Circular and triangular(d) Flat and circular ( )

8. Where TPS cables are run unenclosed, they may be joined using:(a) conduit(b) a TPS J box(c) connectors and PVC tape(d) crimp lugs ( )

9. The sheath colour of TPS cables used for fire alarms is generally:(a) white(b) red(c) orange(d) blue ( )

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10. A TPS cable comprising of red, black and green/yellow is generally known as

cable.

11. TPS cables with more than four cores will always be in shape.

12. Identify the following accessories that are used with TPS cable:

(a) (b)

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Section No: 4 MIMS, SWA & Armoured Cables Purpose:The aim of this section is to provide you with the knowledge and skills to identify the structure, colour coding, applications and termination of mineral insulated metal sheathed, steel wired armoured and various other armoured cables as used in the refrigeration / air conditioning and electrical industries.

Reason for StudyOccasionally you will come across the following cables and you will need to have an understanding of their purpose.

Steel wired armoured (SWA):

Steel Wired Armoured (SWA) cables are constructed with the insulated cores protected from any mechanical damage by the addition of an external layer of steel wire or braided Steel wired armoured cables have a PVC outer covering to protect the armouring from corrosion. Refer Fig. 3.

Fig. 3 Example of Steel Wired Cable (SWA)

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Heat and Flame resistant Cables

Mineral Insulated Metal Sheathed Cables (MIMS)Mineral Insulated Metal Sheathed (MIMS) cable are constructed with one or more cores of single stranded cable enclosed in a continuous metal sheath with compressed powder (magnesium oxide) to insulate the cores from each other and the outer sheath. MIMS is commonly referred to as Pyrotenax. Refer Fig. 1.

This type of cable is used where there are extreme high ambient temperatures up to 250 degrees C and is extremely hygroscopic (absorbs moisture readily). The joining and termination of MIMS require special fittings and seals refer Fig. 2.

Fig. 1 Examples of MIMS cables

Fig. 2 Example of MIMS pot seal joint

Other Types of Heat Resistant Cable:

� Class Fibre Insulated Cable: Used in wiring applications that may involve high temperatures (such as ovens, hot plates and hot water heaters electric duct heaters etc).

� Fire Resistance Cable (Radox): This type of cable is fire resistance, but not heat resistant, That is, it retains its insulating properties when subjected to fire, but is usually physically destroyed. Application: used in the wiring of fire alarms.

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1. Mineral insulated metal sheathed cables can operate at a temperature of:(a) 75 degrees C(b) 90 degrees C(c) 105 degrees C(d) 250 degrees C ( )

2. SWA cables are preferred to TPS cables because of their ability to withstand greater:

(a) voltage(b) temperature(c) mechanical stress(d) permeability ( )

3. Steel wired armoured is usually known as:(a) armoured cable(b) TPS cable (c) lead sheathed cable(d) SWA ( )

4. Care has to be taken when working with MIMS cable due to the ability of the insulation to:

(a) radiate heat(b) absorb moisture(c) soil the workplace(d) become dislodged ( )

5. A fire resistant cable that looks like conventional circular TPS cable is known as: (a) MIMS cable(b) Glass fibre cable(c) SDI cable(d) Radox cable ( )

6. Glass fibre cable is generally use in:(a) low voltage circuits(b) control circuits(c) hot water systems / ovens etc(d) large industrial boiler circuits ( )

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Section No: 5 Data CablesPurpose:The aim of this section is to provide you with the knowledge and skills to identify the structure, colour coding, applications and the termination of various data cables used in the refrigeration / air conditioning and electrical industries.

Reason for StudyJust about all the controls used in the HVAC industry are electronic and they need special cable to carry the very low voltages from the sensors to the controllers.

Data Cables:There are a number of data cables designed to send signals for communication systems such as: Telephones, televisions computers etc. the following details a number of data cables used within the communication network:

� Shielded Cable� Co-axial Cable� Telephone Cable� Fibre Optic Cable.

Shielded Cable.The ‘shield’ is usually in the form of aluminium foil warped around the internal insulated signal carrying conductors.The ‘Shield’ is usually connected to earth and effectively screens the inner cables from induced voltages. Shielded cables have a low frequency and are suited for interconnecting appliances in computers and sound systems. This type of cable cannot be used in place of co-axial cable.

Co-axial Cable:Co-axial cable similar type of construction to shielded cable, but is designed for use at high frequencies (radio frequencies – 200mhz) and is specified by its impedance.

The screen (or earth braid) around co-axial cable The data signals are often measured in microvolts and therefore it is essential to prevent interference to retain a clean signal.

Applications:� Television antenna distribution systems� Signal source for VCR’s� Computer network systems. These systems are referred to as: Local Area Network

(LAN) systems.

Telephone Cable:Telephone cables are used in the telecommunication system and this type of cable is used where screening is not important and where currents and voltages used are low.

Applications:� Cabling for telephones� Intercom systems

Fibre Optic Cable:Fibre optic cables are used to transmit data using pulses of light. The joining of fibre optic cable is a fairly simple task; however the joining and terminating procedures can be very complex and thus requires specialised equipment with a competently trained technician to facilitate these processes. One of the main advantages; of fibre optic cable is that it offers higher security against illegal tapping.

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1. The transmission of data using light rather than electrical signals requires:(a) light duty cables(b) coaxial cable(c) shielded cable(d) fibre optic cable ( )

2. Cables used for the connection of computers, intercoms and alarms which convey small signals at extra low voltages are generally referred to as:

(a) coaxial cable(b) two pair single core, sheathed cable(c) fibre optic cable(d) flexible cable ( )

3. The metal braid around a coaxial cable is usually connected to:(a) the neutral(b) earth(c) the inner core of the cable(d) an isolating point ( )

4. Fibre optic cables have the advantage that they:(a) can carry high voltages(b) can bend easily(c) offer high security against illegal tapping(d) are cheap ( )

1. 5. Telephone systems are usually wired with: (a) coaxial cables

(b) telephone cables(c) TPS cables(d) Data cables ( )

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Section No: 6 Flexible CablesPurpose:The aim of this section is to provide you with the knowledge and skills to identify the structure, colour coding, applications and the termination of single and three phase flexible cables used in the refrigeration / air conditioning and electrical industries.

Reason for StudyFlexible cabling is used extensively to connect between fixed wiring and devices that will vibrated, i.e. compressor, fans and pumps. An understanding of their limitations and their unique colour code is essential.

Flexible Cords (240 Volts)The construction of the flexible cord differs from that of building wire in that the following characteristics:

� Has fine strands of wire� Provides flexibility� It is portable� Rated in light, ordinary and heavy duty.

Note: the international colour coding for flexible cords up to 250 volts is as follows:- active: brown- neutral: Light blue- earth: green / yellow.

It should also be noted that obsolete colour coding was:- active: red- neutral: black- earth: green.

Types of flexible cables:

� PVC sheathed light duty, two or three core� PVC sheathed ordinary duty, two or three core� PVC sheathed heavy duty, two or three core� Parallel, two core unsheathed (figure 8 configuration)� Textile braided cotton covered, (used on irons and toasters etc).

AS/NZS 3000 – 2000 Flexible cords:� Prohibited – cords must not be run through windows, doorways, walls or

partitions beyond the room where they are permanently connected to a device..

� Jointing – Clause 3.7.2.7 Flexible cords, except where used as fixed wiring, shall not be joined except by means of suitable cable couplings.

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Termination of 240 volt flexible cords:The correct termination connections and colour code for a flexible cord connected with a three pin plug top and extension socket is illustrated in Fig. 1 & Fig. 2.In addition the polarity of a GPO is also illustrated in Fig. 2.

International colour coding

Fig. 1

Polarity:The polarity of a GPO is illustrated below in Fig. 2.

Fig. 2 Polarity

of GPO (front view)

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Flexible Cords (415 Volts)The construction of the three phase flexible cord up to 1000 volts differs from that of building wire in that the following characteristics:

� Provides flexibility� It is portable

The majority of three phase (415 volt) flexible cords consist of three active connections, a neutral and an earth. The voltage supply provides for three and single phase connections of appliances:

� Voltage between any two actives 415 volts� Voltage between active and neutral 240 volts� Voltage between active and earth 240 volts.� Voltage between neutral and earth Zero volts

Termination of 415 volt flexible cords:The correct termination connections for a three phase flexible cord using a five pin plug socket connected to an appliance is illustrated in Fig. 3 & 4.

Fig 3

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Fig 4

Colour Code for Three Phase Flexible Cable.

Actives Red, White, Dark Blue, Black and Brown are commonly used.

Neutral Light Blue

Earth Green/yellow

## Always check the neutral conductor colour code if you are connecting a plug to your equipment.##

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1. Joints between flexible cords used for purposes other than fixed wiring can be made:

(a) by means of an approved plug and cord extension socket(b) by twisting the wires together and wrapping in PVC tape(c) in a fixed junction box(d) using soldered connections wrapped in PVC tape ( )

2. Flexible cords, when not used as fixed wiring cannot be held in a position where they:

(a) touch the floor(b) pass through a window(c) can be seen(d) touch an earthed appliance ( )

3. PVC sheathed flexible cords are categorised as:(a) textile, PVC and tinsel types(b) having single, double and multi cores(c) light, ordinary and heavy duty(d) 5A, 10A and 15A current ratings ( )

4. Flexible cables when used for fixed wiring connections must be:(a) terminated by means of an approved plug and cord extension socket(b) terminated by twisting the wires together and wrapping in PVC tape(c) terminated with soldered connections wrapped in PVC tape(d) terminated and inclosed in a junction box ( )

5. Flexible cords used for domestic appliances such as irons, toasters etc are usually:(a) light duty PVC sheathed(b) cotton covered(c) twin core (figure eight)(d) metal braid screened ( )

6. Why shouldn’t flexible cord be run beyond the room they are connected?

7. From the details below fill the correct voltages for a three phase flexible cord plug:

� Between L1 and L2

� Between L3 and neutral

� Between L1 and earth

� Between Earth and neutral

8. What are the two main advantages of a three phase flexible cord?

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9. List the name for each of the connections of a five pin three phase plug in conjunction with a flexible cord.

10. What is the international colour coding for a 240 volt flexible cord connected to an appliance?

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Section No: 7 Appropriate Fixing DevicesPurpose:The aim of this section is to provide you with the knowledge and skills to identify and attach the appropriate fixing devices for TPS cables, PVC steel conduits, cable trays and trunking (ducting) for various electrical installations within the refrigeration / air conditioning and electrical industries.

Reason for StudyWhenever you repair or replace a conductor or associated equipment it must be done correctly, and as a ‘duty of care’ this may require that fix others work.

Installation:The cable runs should be planned for speedy installation and economic use of material. Appearance will also be a factor for surface work. If the wiring is on the surface, it should be installed with cable clips in short sections (300mm apart) and making sure that the cable is installed flat and that there are no kinks. TPS cable should be joined using BP connectors enclosed in an insulated TPS junction box. Note attached diagram Fig. 1

Attachment of TPS Cable:Thermoplastic Sheathed Cables are attached using either metal or PVC clips for either round or flat TPS and these clips should be spaced at a maximum 300 mm.

Note attached diagrams Fig 2 & 3, indicate both PVC and metal clips.

Fig. 1

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PVC and Steel Conduit Accessories:

Accessories used for the support of conduit, both steel and PVC, vary with the method of support, the most common being the conduit saddle and half saddle or clip as shown in Fig. 4, 5 & 6.

Note: the distance between each saddle and or clip should be no more than one metre.

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Cable Trunking / Ducting:A trunking or cable duct is a closed passage structure into which cables are laid or drawn. The construction of cable trunking or ducts can be made of either metal or PVC, note typical cable ducts Fig. 7.

The installation provides for easy access for wiring and for any extensions or additions.

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1. What are the two approved methods for attaching TPS cables and the distance required between each attachment:

2. What is the main advantage of using cable trunking or duct for the installation of electrical cables?

3. Building wire is to be used for the installation of a split ducted air conditioning system, describe how would you provide protect and attachment of the electrical cables?

5. When installing steel conduit using conduit saddles, what is the maximum distance between each saddle?

6. What are the three main factors to be considered before you commence the installation of TPS cable:

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Section No: 8 Competency AssessmentsPurpose:The aim of this section is to validate that you have the knowledge and skills required to isolate, test and tag electrical circuits, make an electrical extension cord, attach a single phase flexible cord to an appliance and attach a three phase flexible cord to an appliance.

Requirements:To enable completion of these competencies you will be required to provide evidence that you have completed training in the following programs or equivalent:

Prerequisites:

� Occupational Health & Safety (7793T)� Electrical Fundamentals (NREF)� Electrical Concepts and Applications (NRECA)� Refrigeration Electrical Wiring (NREW)

Competencies:

� UTE NES208A: Disconnect & Reconnect fixed wired electrical equipment (up to 1000Volts).

� UTE NES 209A: Attach flexible cords and plugs to electrical equipment connected to 240 volt supply

� UTE NES 210A: Attach flexible cords and plugs to electrical equipment connected to a supply up 1000 volts AC ( Three phase 415)

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Practical Assessment

UTE NES208A: Disconnect & Reconnect fixed wired electrical equipment (up to 1000Volts).

Isolate, Test and Tag an Electrical CircuitProcedure:

Isolate the electrical supply to enable the removal of a three phase drive motor from a refrigeration belt driven unit.

Select the appropriate tools, testing meters and associated isolation tags.

Test and tag the electrical circuit in accordance with the established procedures and the current AS/NZS 3000 - 2000 Wiring Rules.

Demonstrate the reconnection procedures.

Your teacher / mentor will check your performance against the established procedures.

Note: Remember Electricity can Kill!

Document the correct procedures for the disconnection and reconnection of an electrical circuit in the space provided below:

Isolating, testing and tagging procedures of an electrical circuit

1.

2.

3.

4.

5.

6

7.

8.

9.

10.

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UTE NES 209A: Attach flexible cords and plugs to electrical equipment connected to 240 volt supply

Task: Making an Extension Lead

Procedure:Connect a three pin plug and plug extension socket to a length of three core flex to make an extension lead which conforms to the current AS/NZ Wiring Rules.

Resources: Suitable length of three core flexible cable Electrical wiring hand tools Three pin plug and extension socket Multimeter.

Remember Electricity can Kill!

Note: diagram below indicates the correct polarity

Conclusion:On completion of the cable connections using a multimeter check that the polarity is correct

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UTE NES 209A: Attach flexible cords and plugs to electrical equipment connected to 240 volt supply

Task: Attach a single phase flexible cord to an appliance

Procedure:Connect a three pin plug to a length of three core flex and terminate the other end at the terminal junction bok for a Room Air Conditioner (RAC) or Domestic refrigerator to comply with the current AS/NZS Wiring Rules.

Resources: Suitable length of three core flexible cable Electrical wiring hand tools Three pin plug Multimeter.


Note: Form the attached diagram draw the interconnecting cable conductors to ensure correct termination and polarity.

Conclusion:On completion of the cable connections using a multimeter check that the polarity is correct.

A

N

E

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UTE NES 210A: Attach flexible cords and plugs to electrical equipment connected to a supply up 1000 volts AC (Three phase 415)

Task: Attach a three phase flexible cord to an appliance

Procedure:Connect a three phase (415 volt) five pin plug to a length of five core three phase flexible cable which is to be connected to the terminals of a three phase appliance (package air conditioning system) in accordance with the current AS/NZ 3000 -2000Wiring Rules.

Resources: Suitable length of three phase flexible cable Electrical wiring hand tools Three phase plug Terminal connectors Multimeter.


Note: Form the attached diagram draw the interconnecting cable conductors to ensure correct termination and polarity.

Conclusion:On completion of the cable connections using a multimeter check that the polarity is correct

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Answers: Review Questions:Section No: 1Q.1 d

Q.2 c

Q3 a

Q4 b

Q5 c

Q6 c

Q7 c

Q.8 c

Q9 Test lamps, Combi-check, multi-meter, clamp-on ampere mater.

Q.10 (a) re-wireable fuse

(b) HRC fuse

(c) circuit breaker.

Q. 11 (a) supply mains

(b) neutral link

(c) MEN link

(d) main isolator switch

(e) fuse/ / circuit breaker

(f) earth conductor

(g) circuit conductors

(h) appliance

.

Q. 12 Thermal circuit breaker relies on the operation of a thermal strip to trip the breaker in the event of excess current flow.

Q.13 The advantages of a HRC fuse is its speed of response and accuracy under high fault currents.

Q.14 Earth leakage circuit breaker (ELCB) Residual current device (RCD)

Q. 15 The current AS/NZS 3000 and 3008 Wiring Rules.

Section No: 2Q.1 a

Q.2 c

Q.3 b

Q.4 d

Q.5 a

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Q.6 Clause No: 4.3.7 in AS/NZS 3000 – 2000 states: the electrical portion of any duct heater installation shall comply with the requirements of this standard and attention to AS/NZS 1668-1 as well as safety requirements contained in AS 3102. In addition compliance within the relevant regulatory authorities may be required.

Q.7 AS/NZS 3008 section 3 refers to types of cables page 16, Clause 3.3.1.2 method of installation and refers to tables 2 (1) to 2 (4)

� Table 2 (1) item 13 column 4 refers to tables 12 and 13.� Table 12 unenclosed, touching indicates 6mm2 with a current rating of 37

amperes.

Q.8 Clause No: 1.4.17 in AS/NZS 3000-2000 states: cable a single core or two or more cores laid together either with or without fillings, reinforcements or protective coverings.

Q.9

� Consumer mains Clause No: 1.4.30 states: those conductors between the point of supply and the main switch board.

� Earthed Clause No: 1.4.40 states: connected to the general mass of earth in accordance with the appropriate requirements of this standard.

� Appliance Clause No: 1.4.6 states: a consumer device other than a lamp in which electricity is converted to heat motion or any other form of energy or is substantially changed in its electricity character.

Section No: 3Q. 1 c

Q. 2 b

Q.3 c

Q.4 c

Q.5 a

Q.6 c

Q.7 c

Q.8 b

Q.9 b

Q.10 A TPS cable comprising of red, black and green/yellow is generally known as twin and earth cable.

Q.11 TPS cables with more than four cores will always be circular in shape.

Q.12 (a) General Purpose Outlet (GPO)

(b) Thermoplastic Sheathed Junction Box (TPS J box)

Section No: 4Q.1 (d)

Q.2 (c)

Q.3 (d)

Q.4 (b)

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Q.5 (d)

Q.6 (c)

Section No: 5Q.1 (d)

Q.2 (a)

Q.3 (b)

Q.4 (c)

Q.5 (b)

Section No: 6Q.1 (a)

Q.2 (b)

Q.3 (c)

Q.4 (d)

Q.5 (b)

Q.6 To maintain the point of isolation with view and prevent mechanical damage to the

cable.

Q.7 Between L1 & L2 415 volts

Between L3 & neutral 240 volts

Between L1 & earth 240 volts

Between earth & neutral Zero volts

Section No: 7

Q.1 PVC or Metal Clips 300mm maximum distance apart.Q.2 The main advantage of using trunking or duct is that it provides easy access for wiring

and any future additions.

Q.3 The building wire could be run in cable trunking that has a removable cover for ease of access and protection.

Q.4 The maximum distance between each steel saddles is one metre.

Q.5 � Cable run should be planned for speedy installation.� Economic use of material.� Appearance where surface work is a factor.

refrigeration electrical wiring -...

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