Answers to classroom activities

Chapter 1

Environmental legislation

Clean Air Act 1993: Ensures that companies operating furnaces, boilers or incinerators use well-engineered combustion equipment A = 3

Pollution Prevention and Control Regulations 2000: Sets directives regarding controlling pollution from certain industrial activities B = 4

Waste Electrical and Electronic Equipment EU Directive 2007: Act that brings compliance regarding European obligation regarding recycling electrical waste C = 5

Environmental Protection Act 1990: Act that ensures that the best practicable environment option is employed to control pollution D = 1

Controlled Waste Regulations 1998: Act that ensures you transfer waste to an authorised company E = 2

Environmental terms and roles

Environmental Health Officer: Person who periodically tests the water quality of recreational water in swimming pools and private water supplies A = 2

Environment Agency: Organisation that has the power to seize vehicles involved in illegal waste disposal B = 1

Landfill: Waste that cannot be recycled C = 4

Built environment: Things we use to build with that can change the environment for everyone D = 5

Public nuisance: An act that interferes with the rights of the public by affecting life, health, property, morals or reasonable comfort or convenience E = 3

Chapter 2

Site paperwork

Time sheet: A record of the work activities of employees on a daily basis A = 3

Delivery note: A record of what material has been delivered on site B = 5

Day work sheet: A record that accounts for any materials and time spent on extra work C = 4

Job sheet: A record of the technical work required to be carried out D = 2

Variation order: A record of any extra work carried out E = 1

On-Site Guide symbols

2 way switch A = 2

Pull switch B = 1

Intermediate switch C = 3

Socket outlet D = 7

Fluorescent lamp: E = 6

Wall-mounted lamp F = 5

Earth G = 4

Chapter 3

Statutory and non-statutory regulations

BS7671 Wiring Regulations: Main non-statutory document that brings about an electrician’s code of practice A = 5

On-Site Guide: Pocket version of BS 7671, although you can read earth loop impedance values directly without correction B = 2

Guidance Note 3: This non-statutory document gives specific guidance on inspection and testing of electrical installations C = 1

Electricity at Work Regulations 1989: A statutory document that details specific precautions when working with electricity at work D = 4

Health and Safety at Work Regulations 1974: A health and safety umbrella Act from which other statutory regulations were formed E = 3

Chapter 4

Testing Position

Measurement of Prospective Fault Current, values expected to be in KA:

Measured at the supply origin to ensure its maximum value is documented to ensure that switch gear & protective devices are assessed for breaking capacity A = 1

Stated Loop impedance values have to be multiplied by 0.8: Reading Zs from BS7671 B = 4

Loop impedance values can be read directly as stated: Reading Zs from the On-Site-Guide or Guidance Note 3 C = 2

Measuring Earth Loop impedance: Measured at the furthest most point to ensure its maximum value is low enough to comply with shock protection requirements D = 3

Testing earth electrode resistance: Protective equipotential bonding is disconnected E = 6

Measuring Prospective Fault Current: Protective equipotential bonding is connected F = 5

Dead test values

0.05–0.08Ω - High fault current will flow and lead to a protective device operating quickly: Acceptable range of values for Continuity of Circuit Protective Conductor A = 2

1MΩ – Within limits but possible Latent fault: Acceptable value of Insulation Resistance but further investigation is recommended B = 3

2MΩ: Acceptable value of Insulation Resistance C = 4

500V: Insulation resistance meter setting for a domestic single phase supply D = 5

NULL: Built in test equipment facility that removes value of test leads from reading under test. Alternatively subtract meter leads from measured value E = 1

Chapter 5

Fault symptoms

Details and symptoms of the fault: Talk to the customer, job sheet, carry out functional test A = 2

Is the circuit deteriorating slowly? Compare previous testing data (schedule of test results), maintenance records regarding component replacement B = 1

Confirm correct size of circuit and protective conductors: Refer to BS7671, On-Site Guide, GN3 C= 5

Evaluate if equipment is operating operates correctly in different modes of operation: User guide D = 4

Technical advice on how to install equipment: Manufacturer’s instructions E = 3

Symptoms and corrective action

No evidence of overcurrent but cable insulation is showing signs of deterioration (heat damaged): Possible overloading: increase size of conductor A = 2

Circuit cannot achieve disconnection times: install a supplementary bonding conductor B = 5

Assembly line motors are sluggish in operating after the circuit conductors were extended in length: Possible volt drop issue – increase size of assembly line motor conductors C = 1

Upstairs sockets circuit breaker trips when I stand near the bedroom door: Suspect loose floor board impacting on cable installed too close to the surface D = 3

Relay has burnt out: If a short circuit is not apparent, then check design current against relay rating E = 7

Incorrect rotation on three-phase motor: Two of the line conductors are cross connected F = 4

No indications of short circuit but circuit breaker operates as soon as power is applied: Check condition, type and rating of circuit breaker matches load requirements G = 6

Chapter 6

Motor control

Direct on line starter: Is used to start motors rated <5 kW A = 2

Star delta starter: Is used to start motors rated at between 5 kW to 20 kW but only when motor can be started against light or no load B = 3

Autotransformer starter: Starter that can be used to start heavy loads C = 4

Rotor resistance starter: Used to start wound rotor resistance D = 1

Electrical components

Relay: A device that uses low power to control a larger powered system A = 3

A relay comprises: Solenoid and contacts B = 4

Contactor: Heavy duty relay C = 2

Tungsten: Type of metal used in heavy duty contacts D = 1