AM2

GUIDE TO THE AM2 EXAM

What is AM2? AM2 or the Achievement Measurement 2 is a practical performance skill test administered by the National Electrotechnical Training (NET). You must take the AM2 test if you are: • An Apprentice finishing your JIB Apprentice Training Scheme

• Finishing an Electrical Installation Apprenticeship

• An oversees qualified electrician (from Poland or Hungary for example)

who needs approval in order to gain the JIB card as an electrician

• From January 2011 the AM2 requirements have changed, which means that all candidates must take the exam according to the new program.

Candidate requirements The AM2 is designed for individuals who wish to work as electricians or as maintenance electricians. By taking the new AM2 exam you will demonstrate that you have a level of co13petence expected by the industry in the following key occupational areas: • The interpretation of specifications, drawings and diagrams, • Risk assessments and also Health and Safety, • Safe isolation, • Planning and preparing to install, terminate and connect identified wiring systems, • Inspection, testing and certification of electrical installations, • Fault diagnosis and fault correction, • The understanding and application of industry recognised procedures, working

practices and the requirements of statutory and non-statutory regulations. You will be required to work on: • Lighting and power circuits, • A three-phase distribution board and sub-circuit, • A central heating/sustainable energy system, • A safety services circuit and device, • A data cabling system.

The AM2 Exam

The assessment is split into these sections: Section A1 – Risk assessment and safe isolation – Time to complete: 1 hour Section A - Composite installation – Time to complete: 8 h 30 min Section B – Inspection, Testing and Certification – Time to complete: 3 h 30 min Section C – Fault Diagnosis – Time to complete: 2 hours Section D – On-line exam – Time to complete: 1 hour All the sections must be completed within the specified target times and according to the requirements of the current IEE Wiring Regulations (BS7671). You will be required to work on standard AM2 test units using drawings, circuit diagrams and written instructions. You will be permitted to refer to the current edition of the IET Wiring Regulations, IET On-Site Guide and to the IET Guidance Note no.3 Inspection and Testing.

AM2 EXAM SECTIONS – RISK ASSESSMENT AND SAFE ISOLATION

Section A1 consists purely of the completion of a risk assessment form provided by your assessor and by performing safe isolation on the AM2 exam unit which you will be working on. The target time specified for this section is 1 hour, which should be enough to complete both tasks without the pressure of not having enough time. In order to prepare yourself for this part of the exam feel free to read through our relevant guides:

http://www.sparkyfacts.co.uk/Safe_Isolation_procedure_for_dead_working.html

http://www.sparkyfacts.co.uk/Guidance_to_Electricians_Risk_Assessment_Form.html

You must perform a 100% correct safe isolation process in order to

pass this part of the AM2 exam.

Practice safe isolation with a friend or colleague until you do every

step without thinking about what step to do next.

Don`t forget to place the key in your pocket after you lock the

padlock on the isolator! Many people forget that or don’t know what

to do since the key is not their property.

Just keep it in your pocket and return it after the work is done.

AM2 exam Section A – Composite installation This is the longest section in the new AM2 exam. You will have 8 h 30 min to finish all the tasks at hand. You will be expected to install the following: • Protective devices in a TP&N distribution board • A two-way and intermediate lighting circuit in a PVC/PVC multi-core cable • A BS 1363 13A socket outlet ring circuit in a PVC single core cables • A carbon monoxide detector safety service circuit in a FP200 type cable • Data outlets circuit in a Cat 5 cable • A BS EN 60309 16A socket outlet in a XLPE SWA cable • Protective equipotential bonding to gas and water services • A 3-phase direct on line motor/starter circuit in a SY cable • An S Plan central heating and hot water system with a solar thermal

sustainable energy element utilising heat resistant flexible cable and PVC single core cables

AM2 Section B – Inspection, testing and certification • You will be required to demonstrate occupational competence in each of these tasks: • Performing a Safe Isolation Procedure to ensure the installation is safe to work on • Carrying out visual inspection of the installation in accordance with BS 7671 and IEE

Guidance Note 3. • Completing all the relevant tests on the installation in accordance with BS 7671 and IEE

Guidance Note 3: • Continuity of protective conductors • Continuity of ring final circuit conductors • Insulation resistance • Polarity • Earth fault-loop impedance • Prospective fault current • RCD test • Functional testing • Completing the electrical installation certificate, schedule of inspections and schedule

of test results. • You will have 3 h 30 min available for this section. You will be required to perform a

100% correct inspection, testing and certification process in order to pass this part of the new AM2 exam.

AM2 Section C – Fault diagnosis You will be required to demonstrate occupational competence in these tasks: Correctly identify and use tools, equipment and instruments that are fit for purpose. Perform a safe isolation procedure to ensure the installation is safe to work on. Identify faults from the fault symptom description given by the examiner. State and record how the identified faults can be rectified. You will be presented 7 random faults to investigate and diagnose. You will have to state the methods required for repairing the faults. Target time for this section is 2 hours. In order to be successful in this part of the new AM2 exam you must be able to read, follow and understand circuit diagrams of potentially complicated circuits like the S plan heating system with solar incorporated. The faults should be found using logical and methodical approach with the aid of common test equipment.

Your biggest friend for finding the faults will be the low ohm reading continuity

tester.

Remember, all faults will be wiring faults! There will be no faulty components. You

will encounter short circuits, open circuits, reversed polarity faults, low insulation

resistance and cables connected to incorrect terminals.

AM2 Section D – the online exam This part of the new AM exam consists of thirty questions, and the maximum time is one hour. The exam covers the following areas: • Health & safety • Hand tool use & care • BS 7671 IEE Wiring Regulations • Motor control & overload protection • Installation techniques • Building regulations • Environmental/Sustainable systems • You will be allowed to use the following books during the exam: • BS 7671 IEE Wiring regulations • IEE On Site Guide • IEE Guidance Note 3 • Electrical Installers guide to the Building Regulations

We recommend to familiarise yourself with contents of the above stated books. Time will be against you so it is important to be able to find the answers fast enough within the books.

PROTECTIVE DEVICES IN AM2

During the new AM2 exam, as a part of the composite installation you will be required to determine and select the appropriate protective device for every circuit. You will be provided with a selection of protective devices but among the right ones there will also be some which are not suitable for the given circuit. You will be expected to know which ones to avoid for a given type of circuit.

At the end of this text you will find the correct selection of protective devices for every circuit in the AM2 composite installation exam. It is vital for you to know how to choose the right protective device for a certain circuit in order to be competent for electrical installation work. We have prepared a short guide just for this.

Determining the protective device characteristics for circuits in the AM2 exam Electrical installation design can be a long process. However, in the AM2 exam there are given details for every circuit, which makes the design much easier and faster. All you need to know is to use the given details to select the appropriate protective device for a given circuit. The main formula we can start with: Iz >= In >= Ib Ib – design current of circuit (A) (the load to be connected to the circuit) In – nominal current of protective device (A) Iz – effective current carrying capacity of cable (A) This means that in every circuit at all times the current carrying capacity of the cables must be higher than the highest possible load current. Also the protective device rating must be higher than the load current but lower than the maximum current carrying capacity of the cable installed.

Now let’s go through the AM2 exam composite installation circuits: Circuit 1: CO detector in FP200 type cable (AM2 Exam) Given are two very important details: • One is that the CO detector uses very little energy, even less than 1A.

• The other given detail is the size of the FP200 cable provided which is

1.5mm2 • Starting from Table 4D1A in Appendix 4 of BS7671 IET Wiring Regulations

we can determine the current carrying capacity for any given cable.

It is recommended to remember the values for the most common cables in use like the 1.5mm2 and 2.5mm2 twin and earth or the 2.5mm2 singles cable.

The 1.5mm2 cable can handle up to 16A depending on other factors which are not relevant right now. This means that our protective device could be selected up to the size of 16A. Considering that our CO detector uses less than 1A current, we can see that the 16A rated protective device is too big for this load. We can choose the one which is closest to our demand and readily available; that would most certainly be the 6A MCB protective device. To determine the type of the protective device you will have to know which type is suited for which situation. There are many old and new type MCB`s on the market today but the most common ones are the C, B, and D types. The letters indicate the instantaneous tripping current of the device:

Table 1. Short guide to the types of MCB`s

Type B Above 3 In up to and including 5 In

Suitable for domestic use

Type C Above 5 In up to and including 10 In

Suitable for commercial and light industrial use

Type D Above 10 In up to and including 20 In

Suitable for industrial use

After assessing all the details we can determine that the CO detector circuit installed in FP200 1.5mm2 cable is best protected with a 6A Type B MCB.

Circuit 2: The lighting circuit (AM2 Exam) To determine the size and type of protective device for the circuit once again we look at the given details: There is only one 28W fluorescent lamp to be supplied with a current consumption of less than 1A 1.5 mm2 twin and earth cable is provided for the circuit with a maximum current carrying capacity of 16A Following the same steps as with the first circuit, we can determine that the ideal protective device for this circuit will be the 6A Type B MCB.

Circuit 3: BS EN 60309 16A socket outlet (AM2 Exam) Given details: Maximum load will be not more than 16A 2.5mm2 SWA cable with current carrying capacity of more than 20A is provided for the circuit Since it is unlikely that a 16A socket outlet would be installed in a domestic environment, a Type C MCB is recommended. From these details we can determine that the ideal protective device for this circuit will be the 20A Type C MCB.

Circuit 4: 13A socket outlet ring circuit (AM2 Exam) Given details: Ring circuit with 13A socket outlets 2.5mm2 twin and earth cable The Ring Circuit or Ring Main is a unique circuit arrangement which is preferred in the UK. It is usually used in domestic environment, with 2.5mm2 cable connected in to the ring formation and protected by a 32A Type B MCB. The size of the protective device is suitable because the 2.5mm2 cable is connected in ring formation which will effectively double the current carrying capacity to each socket on the ring. One un-fused spur is allowed from every socket to only one double or single socket in 2.5mm2 cable. Because of the nature and use of the ring circuit in the AM2 exam we do not need to take into consideration the area covered or the circuit length regarding voltage drop for the circuit. Given the details we can determine that the ideal protective device for this circuit is the 32A Type B MCB.

Circuit 5: S Plan central heating and hot water system with a solar thermal sustainable energy element (AM2 Exam) Given details: 2.5mm2 heat resistant flexible cable with current carrying capacity of more than 20A 2.4mm2 PVC singles cable with current carrying capacity of more than 20A Because this system forms a part of the AM2 exam, some parts of the installation are not physically present but are simulated instead, so we cannot know for sure what the current load will be. According to design rules ( Iz>=In ) our protective device must be of that size so that it can safely protect the cables in the installation. Given these details we can determine that the ideal protective device for this circuit will be a 16A Type B MCB or a 20A Type B MCB.

Circuit 6: 3-phase direct on line motor/starter circuit (AM2 Exam) Given details: 1 KW motor with a current load of about 5A 1.5 mm2 SY cable with maximum current carrying capacity of 16A 1.5 mm2 PVC singles cable with maximum current carrying capacity of 16A Even if the motor is not physically there we still need to bear in mind that it can be connected at any time. A motor on a DOL starter (Direct On Line) will have a much higher starting current (up to six times) than the one under normal operation. However, this starting current will have an effect only for the first milliseconds of the start, which can be dealt with a higher rated C type MCB. Given the details we can determine that the ideal protective device for this circuit is a 10A Type C MCB.

Circuit Protective device

CO detector circuit 6 A Type B MCB

Lighting circuit 6 A Type B MCB

16 A socket outlet circuit 20 A Type C MCB

13 A socket outlets ring circuit 32 A Type B MCB

S plan heating system with solar thermal circuit

16 A Type B MCB

DOL motor starter circuit 10 A Type C MCB

This table states the correct selection of protective devices for

every circuit in the AM2 composite installation exam:

As a part of the AM2 exam you will have to wire up a 2 way and intermediate lighting circuit with one light. There is more than one way to do this, depending of the type of cable available and on the installation requirements.

Years ago it was very common to wire lighting circuits in singles cable and by this minimising the use of copper. Today, this method is rarely used. An example would be an industrial installation where everything is wired with singles cable in steel conduit containment. Most of the time electricians use flat Twin & Earth cable for wiring pretty much everything in domestic installations. Commercial installations can vary, but flat Twin & Earth is the most common cable used. Reflecting this practice, the AM2 exam requires you to wire the lighting circuit with the use of flat Twin & Earth cable. There are many different types of this cable, but what we need to know regarding lighting circuit wiring is that there is also a cable called flat 3 Core and Earth. While the Twin & Earth cable comprises two live wires (Line and Neutral – brown and blue) and an Earth wire, the 3 Core & Earth cable consists of three live wires (brown, black and grey) and an Earth wire. These three cores make wiring a two-way or two-way and intermediate lighting circuit allot simpler and faster.

REVERSED 3-PLATE WIRING SYSTEM FOR LIGHTING CIRCUIT Currently, it is possible that AM2 centres will ask you to wire the lighting circuit using the “reversed 3-plate” system where instead of taking your L and N feed (live conductors) to the ceiling rose, you will be expected to take the feed to the switch first and terminate the neutral conductors within the back box using a connector block!

Step 1: Your light will more than likely be a simple domestic light. These lights are designed to have the means for all the connections necessary. This means that your supply cable (1.5 mm2 flat Twin & Earth) will go straight to the light. The light will have terminals available for the Earth connections and for the Neutral connections. Once you connect your supply cables Earth and Neutral wires to the available terminals, your light itself is connected to Earth and Neutral. At this point you will have the Line wire of the supply cable still not connected. This wire needs to be connected to the available spare connectors. Do NOT connect the Line wire to the Line terminal because then your light would be permanently ON. What we need is to utilise the two-way and intermediate switching available.

Once you complete this, you will need a new length of flat Twin & Earth cable which will go from your light to the first two-way switch. Connect the Line wire of this cable to the supply cables Line wire. Connect the blue wire to the Line terminal, but not before you put some brown sleeving on the blue wire. This will indicate that this blue wire, which normally is a Neutral wire, will this time be used as the brown (Line) one. This will be your Switched Line (SWL). This will be the return path from the switches.

Once completed it should look like this:

Note that this is the case if a domestic light pendant is available for the exam. If the light is anything different, then you will have to use Push-In connectors or regular connectors (instead of the otherwise available connectors) to make all the necessary connections.

Two way and intermediate lighting circuit wiring diagram

The wiring diagram above is what you need to memorise in order to wire the circuit on the day of the AM2 exam. It might look intimidating at first glance, but actually it is quite simple. Let’s break it down to steps.

Step 2: Now that the hardest part has been completed, you will have to wire up the light switches. The cable coming from the light, to the first two-way switch is where you need to continue. You will have to connect the brown (Line) wire to the L1 terminal and the blue wire with the Brown sleeving on it (Switched Line) to the L2 terminal. After this step you will need a length of the 3 Core & Earth cable. Connect the Black wire to the L1 terminal, together with the Brown wire from the other cable (two wires in the same terminal). After this, connect the Grey wire to the L2 terminal, together with the other Blue wire cables with the brown sleeving on it (again two wires in one terminal). Finally, connect the Brown wire to the C (common) terminal. Do not forget to connect all the Earth wires together!

Once completed it should look like this:

Step 3: Now it is time for the Intermediate switch to be wired up. Simply connect all the wires according to the wiring diagram. Note that you will have to use a Push-in connector or any other regular connector to connect the brown wires together. This is because there is no dedicated connection for this on the Intermediate Switch. After this, get a new length of the 3 Core & Earth cable, which would go to the last two-way switch and connect all the wires. Connect black to the other L1 terminal, grey to the other L2 terminal and brown to the separate Push-in or regular connector. Do not forget to connect all the Earth wires together!

Once completed it should look like this:

Step 4: Connect the last two-way switch in accordance with the wiring diagram. Connect black to L1, grey to L2 and brown to C (common).

This is it! You have wired up the Two-way and Intermediate Lighting Circuit. The protective device for this circuit is a 6A Type B MCB.

It is extremely important to put brown sleeving on the blue wire to indicate

that that is a Switched Line wire and not a Neutral wire. Otherwise you

might fail the exam even if the lighting circuit works fine.

The cables selected for this task should be 1.5mm2. Make sure to use

cables with the right cross-sectional area.

13A SOCKET OUTLET RING CIRCUITS (AM2 EXAM)

During the AM2 exam you will be presented with 3 already mounted sockets and a fused connection unit which will have to be wired in a ring circuit with the exemption of one of the sockets which will have to be wired as an un-fused spur from one of the other sockets. To do this simply follow the diagram below. You will be required to use 2.5mm2 single core cables which must be placed in to the middle part of the compartmental trunking. The wiring is really simple. You will start in the CU with 3 lengths of single core cables (brown, blue, yellow-green) from the protection device to the nearest socket. From here you will continue to the next unit which is the fused connection unit. From here to the last socket and from there back to the protection device in the CU. After this you will have to connect another length of 3 single core cables from one of the sockets to the IP rated socket which will be your spurred socket.

The correct protection device for this circuit is a 32A Type B MCB.

CARBON MONOXIDE DETECTOR CIRCUIT (AM2 EXAM)

Installing a carbon monoxide detector is part of the AM2 exam. This is one of the simplest

tasks in the AM2 exam since all you have to do is to choose the correct cable and protective

device and connect the preinstalled detector to the CU.

You will be using 1.5mm2 FP200 cable for this task. The fireproof FP200 cable will need to

be secured on the preinstalled cable tray using fireproof ties with fireproof glands at the fused

connection unit.

You will start by connecting the fused connection unit to the protective device in the CU and

follow by connecting the load side of the fused connection unit to the detector itself.

The correct protective device for this circuit is a 6A Type B MCB.

RJ45 DATA OUTLETS CIRCUIT (AM2 EXAM)

A new addition to the AM2 exam is the data circuit with the use of Cat5e cable. In modern

times electricians are required to deliver not only the electrical containment but the IT

infrastructure of the building as well. This usually involves the installation of LAN networks

which use Cat5e cable and data outlets.

For this task you will need a special tool – a “PunchDown” tool which will be provided by the

examination centre.

All you need to do is to connect the two data outlets together with Cat5ecable.

To do this you will need to follow the colour codes on the data outlets and make sure that

every wire goes to the same coloured terminal on both data outlets.

It is very important that the Cat5e cable must be placed in to the top or bottom section of the

compartmental trunking and where it is necessary to cross the middle section a bridging part

must be inserted in to the middle section of the trunking.

16AMP SOCKET OUTLET CIRCUIT (AM2 EXAM)

This part of the AM2 composite installation exam is one of the most difficult ones. You will be required to terminate SWA cable from the CU to the nearby IP rated isolator. It is required that the cable is exactly the right length so that it will be placed on the preinstalled cable tray with a 90° bend. From the isolator you will be required to use 2.5mm2 singles cable to the 16A socket outlet. Terminating SWA cable takes a lot of practice to master. The best way to learn is to get a short length from somewhere and practice with a SWA gland until you do it fast and precisely every time. Do not be confused if you will be presented with a four core SWA cable. This simply means that you will have to use the outer metallic sheeting of the cable as Earth. In the case that you are presented with a five core SWA cable you will still need to earth bond the outer metallic sheeting of the cable. This circuit is ideally protected by a 20 A Type C MCB.

PROTECTIVE BONDING (AM2 EXAM)

Bonding is designed to limit the voltage level of any accessible electrically conductive parts in order to reduce the risk of electric shock. Main bonding is the electrical interconnection between the main earthing terminal and the incoming metallic services (water, gas or oil pipes) plus any other extraneous conductive parts of a building or an installation. On the AM2 exam you will be presented with TN-C-S earthing arrangements. According to regulation 544.1.1 and Table 54.8 of the IEE Wiring Regulations (BS7671 17th edition) the required size of the main bonding conductor is 10mm2 for supplies with a Neutral conductor of 35mm2 or less. Because of this you will be required to use 10mm2 single core earth cable to connect both the incoming water pipe and the incoming gas pipe to the main earthing terminal inside the CU.

3-PHASE DOL MOTOR/STARTER CIRCUIT (AM2 EXAM)

This part of the AM2 exam requires you to wire up a 3 phase DOL motor starter to a simulated 1 KW motor. Although this might sound as a difficult task it is not. The DOL starter itself is already prewired for you. All you need to do is to connect a 3 phase supply to the starter itself and connect the cable supply from the starter to the motor. To start you would use 1.5mm singles cable from the 3 phase protection device in the CU to the DOL starter. Singles cable is acceptable for this task since it will be located in steel trunking. As always on the new AM2 exam – you don`t need to worry about the trunking itself because it is already preinstalled for you. From the DOL starter you will be using SY cable to supply the simulated motor. You will need to terminate the SY cable with the appropriate SY cable glands. We recommend that you practice this before the exam so that it won’t take too much time. Don`t forget to secure the SY cable to the preinstalled cable tray with cable ties. The required protection device for this circuit is a 10A Type C MCB.

S PLAN CH AND HW SYSTEM WITH SOLAR (AM2 EXAM)

As part of the new AM2 exam you will be required to fully wire up an S plan central heating and hot water system with a solar thermal element. This part of the new AM2 is the most time consuming one so our advice is to leave it to the end so that you can spend all you remaining time on it if needed. The easy part of this task is to supply the system from the CU via a Fused Connection Unit. To do this you will need to use 2.5mm2 singles cable run in the metallic trunking to the FCU from the protection device inside the CU. From the FCU you will continue with 2.5mm2 singles cable to the appropriate connectors in the wiring centre box. At this stage you will need to follow the provided wiring diagram to wire up the whole system. Being able to follow wiring diagrams is essential to finish this part of the AM2 exam. The recommended protection device for this circuit is a 16A Type B MCB.

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