e Flashcards
1
Q
A set of documents, plans or diagrams which sets out requirements for materials, components and service.’
What is this sentence describing?
A
A specification
2
Q
Which document would provide more detailed information on protective equipotential bonding?
A
Guidance Note 8
3
Q
BS 7671 is what kind of document?
A
non-statutory document
4
Q
Would IET Guidance Notes be appropriate to find detailed information on Periodic Inspection and Testing?
A
Yes
5
Q
Would Electricity at Work Regulations be considered a source of technical information?
A
it would NOT be considered a source of technical information
6
Q
Which set of documents can the design electrician use to determine how the regulations can be applied to specific situations?
A
IET Guidance Notes
7
Q
‘The system is to consist of single core thermoplastic cables installed in galvanised trunking run at a height of 2.3m above ffl.’ This statement could form part of what type of document?
A
Installation specification
8
Q
‘The document showing the location of electrical equipment in an electrical installation is a:
A
layout diagram
9
Q
Which type of diagram shows how a system works and helps in fault finding?
A
Schematic
10
Q
Which type of diagram best shows a sequence or process?
A
Block diagram
11
Q
What is the maximum current demand, after diversity has been applied, for a 15kW cooker connected to a 230V supply?
The cooker isolator does not incorporate a 13A socket outlet.
A
26.57 A = current
15kw * 1000 = 15000w
I =P/V = 15,000/230 = 65.22A
65.23A-10A + (30% of 55.22 A) =
16.57 A
16.57 A + 10 A = 26.57A
A 32A circuit breaker would be sufficient to protect this circuit.
12
Q
Calculate the maximum assumed current demand, allowing for diversity.
The cooker isolator is fitted with a 13A socket outlet.
4 x 2.75kw hob plates
1 x 2.5kw top oven
1 x 4.5kw main oven
A
35.48 A
(4 x 2.75) + 2.5 + 4.5 = 18 kW
I =P/V = 18,000/230 = 78.26 A
10 A + (30% of 68.26 A) = 20.48 A
20.48 A + 5 A (for socket outlet) = 35.48 A
A 40A circuit breaker would be sufficient to protect this circuit.
13
Q
In an open circuit the detectors are connected in:
A
Parallel
The open circuit detectors are connected in parallel. If a detector senses heat or smoke, it will short circuit creating a large current and trigger the alarm.
14
Q
What device is connected to the end of an open circuit in order to check that the circuit has not been broken?
A
An end of line monitoring resistor allows a small current to flow which shows the circuit is complete. If the circuit is broken, the current will not be detected by the alarm panel and the panel will go into ‘fault’ mode, usually identifying the fault with an LED or code on the LCD display.
15
Q
matched to correct descriptions
A
Maintained = Classification of emergency lighting
EOL monitoring resistor = Found in fire alarms, large domestic and commercial fire alarm systems
Tamper circuit = Found in fire alarms, large domestic and commercial fire alarm systems
16
Q
CAT1
A
Originally used for telephones.
17
Q
CAT2
A
Voice and Data
18
Q
CAT3
A
ethernet networks as well as digital voice communications
19
Q
what are the different drawing types used in the electrical industry?
A
architectural plans - layout and ‘as fitted’ drawings
circuit diagrams
wiring diagrams
schematics
bar (gantt) charts
block diagrams.
20
Q
types of drawing most likely to be encountered by installation electricians
A
Architectural plans
21
Q
what is a circuit diagram
A
A circuit diagram is the representation of a circuit arrangement that permits easier understanding of how the circuit works
22
Q
what does a wiring diagram show
A
A wiring diagram shows how a circuit is actually wired in practice
23
Q
what do Schematic diagrams show
A
used to show the workings of more complicated circuits including their component parts
24
Q
what is a Bar or Gantt chart used to show
A
Commonly used to show a sequence of work over a specific time period.
25
what are Block diagrams used to show
Block diagrams can be used to show a process or sequence of events like a cooker circuit
26
Which type of diagram shows how a system works and helps in fault finding?
Schematic
27
Which type of diagram best shows a sequence or process?
Block diagram
28
Which type of diagram allows a contractor to plan a sequence of work over time?
Gantt chart
29
Which type of diagram shows a simplified view of an electrical circiuit?
Circuit diagram
30
what are symbols used on
Symbols are used on architectural plans (layout diagrams) to show the desired position of electrical components
Symbols are also used in layout diagrams to show the types and positions of accessories and equipment
31
in what books and where can a selection of symbols be found
A selection of symbols can be found on the inside rear cover of the Electrician's Guide to the Building Regulations as well as the On-Site Guide.
32
what is a key or legend on a drawing
a ‘key’ or a 'legend' shows what each specific symbol represents.
33
most common scales in electrical installation are
: 1:20, 1:50, 1:100
34
most common scales on large industrial electrical installations are
1:200, 1:500 or 1:1000
35
how do space heaters heat a room
primarily by convection or by radiation.
36
how does a convection heater work
convection heaters, heating elements either warm the air directly, or heat oil or another filler, which in turn transfers heat to the air
37
what spectrum do Radiant heaters radiate on
radiate their energy primarily in the infrared spectrum
38
what is a primary advantage of a radiant heater
The advantage of radiant heaters is that the radiation they produce is absorbed directly by clothing and skin, without first heating the air in the space. This makes them suitable for warming people in poorly-insulated rooms, or even outdoors
39
what temperature is an immersion heater heating the water to and why
water reaches the required temperature; this is usually set at 55–60°C to reduce the risk of scalding and high enough to prevent the risk from Legionella.
40
what regulation, circuit and switch is necessary for immersion heaters
Regulation 554.3.3 of BS 7671 requires that the immersion heater must be fed from its own circuit and connected through a double-pole linked switch installed adjacent to the cylinder and connected by heat resistant flex.
41
what circuit and switch is necessary for an electric shower
The shower unit is fed from its own circuit in the consumer control unit and a double-pole linked switch is installed in the vicinity of the shower unit.
42
what are the two common ways to wire and emergency alarm
two common ways to wire an emergency alarm circuit.
Open Circuit
and
Closed Circuit.
43
what are the advantages and disadvantages of a closed circuit emergency alarm system
In the closed circuit arrangement the circuit is complete or ‘closed’ and detection devices open to break the circuit to initiate an alarm condition.
The advantage of this system is that if a circuit conductor or connection is broken, the alarm will operate.
The disadvantage of this system is that, as the detectors are connected in series, the circuit must be interrupted to insert additional sensors.
44
how does an open circuit emergency alarm system opperate
Monitoring is achieved by connecting an end of line (EOL) resistor.
A monitoring voltage is applied to the circuit, this generates a small current which will confirm that the circuit has no breaks. If there is no current flow, then the alarm assumes there is a break in the circuit and goes into 'fault' mode and displays a warning light on the control panel.
When a detector closes, the EOL resistor will be short-circuited and the current will increase greatly, which will be detected by the control panel and will initiate an alarm condition.
45
what methods of detector do intruder alarms use
Intruder alarms are designed to detect an intrusion or attempted intrusion into premises.
A range of detectors are available:
Break glass detectors.
Door and window contacts.
Passive infrared movement detectors.
Ultrasonic movement detectors.
Microwave movement detector.
Beam break detectors.
46
what type of circuits are intruder alarms and what other circuit do they incorporate
Most intruder alarm systems are wired closed circuit as a failsafe measure, so that if the cable is cut the alarm is initiated anyway.
Additional protection is provided by installing a tamper circuit that is run alongside the detector circuit
47
what are the two classifications of emergency lighting
There are two classifications of emergency lighting:
Maintained
Non-maintained
48
In an open circuit the alarm detectors are connected in
Parallel
49
What device is connected to the end of an open circuit in order to check that the circuit has not been broken?
End of line monitoring resistor
50
matches
Maintained - Classification of emergency lighting
EOL monitoring resistor - Found in fire alarms, large domestic and commercial fire alarm systems
Tamper circuit - Used in intruder alarm systems
51
data cables are terminated into
RJ45 modules are used to terminate data cables and require a specialised tool known as a ‘push down tool’
52
advantages & disadvantages of Fibre-optic cables
Advantages
very large data transfer rates
no electromagnetic interference
longer lengths of run without the need for repeaters
better data security.
Disadvantages
high installation cost
complicated installation procedure
possible health risk during installation.
53
what are the possible health risk during installation of Fibre-optic cables
Handling fibre optic cables can result in skin and eye injuries from glass shards, and the risk increases if these are ingested, which can lead to serious internal organ damage.
Chemicals are commonly used to clean or process fibres, and this should only be undertaken in well-ventilated areas.
Never look down the end of a fibre-optic cable when in use as the strong light can cause injuries to the retina.
wear appropriate PPE
54
if we do not know the rating of a light source:-
we assume it to have a rating of 100 watts minimum. This is the maximum size lamp that can be fitted in most domestic lamp holders.
This can be referenced to Appendix A in your OSG (Table A1) page 137 2022
55
1 Gang 1 Way
This type of switch is called one gang as there is only one rocker switch.
The switch only has two terminals - Common and L1, and therefore can only be used to turn a single lighting point 'on' or 'off'.
56
1 Gang 2 Way
This type of switch is called one gang as there is only one rocker switch.
Two way refers to the type of switching arrangement.
The terminals on this switch are: Common, L1 and L2.
57
2 Gang 2 Way
Two gang, two-way, has the same terminals as a two-way switch.
However, it has two rocker switches on the one plate, which makes it two gang.
Each rocker switch has a Common, L1 and L2
58
Intermediate switch
Intermediate switches are used when switching a lighting point from more than two locations.
The terminals are: L1, L2, L3 and L4
59
why does regulation 314.1 in BS 76 state wiring should be divided into several lighting circuits
In order to ensure there is not a complete blackout when a fault occurs, we should install at least two lighting circuits in the premises.
You can reference this to Regulation 314.1 in BS 7671.
60
Regulation 411.3.1.1 in BS 7671 states
An earthing terminal and CPC must be provided at all lighting points, including switches and ceiling roses.
This is a requirement of Regulation 411.3.1.1 in BS 7671.
61
lighting circuits must be protected by a
A 6 amp protective device will normally be used to protect a domestic lighting circuit.
Lighting circuits in domestic properties are also required to have additional protection by RCD.
An RCBO has the properties of a circuit breaker and RCD.
References can be made to:
OSG Section 7.2.5 (note c) page 87 2022
OSG Table 7.1(i) page 74 20022
EGBR Table 4.1.2a page 69 2022
EGBR Section 4.6 page 76 2022
62
lighting circuits must be protected by a
A 6 amp protective device will normally be used to protect a domestic lighting circuit.
Lighting circuits in domestic properties are also required to have additional protection by RCD.
An RCBO has the properties of a circuit breaker and RCD.
References can be made to:
OSG Section 7.2.5 (note c) page 87 2022
OSG Table 7.1(i) page 74 20022
EGBR Table 4.1.2a page 69 2022
EGBR Section 4.6 page 76 2022
63
lighting circuits must be protected by a
A 6 amp protective device will normally be used to protect a domestic lighting circuit.
Lighting circuits in domestic properties are also required to have additional protection by RCD. The RCBO in the image (shown) has the properties of a circuit breaker and RCD.
References can be made to:
OSG Section 7.2.5 (note c) page 87 2022
OSG Table 7.1(i) page 74 20022
EGBR Table 4.1.2a page 69 2022
EGBR Section 4.6 page 76 2022
64
Domestic lighting circuits are generally wired in
1.0mm² or 1.5mm² cables.
65
How many types of wiring systems can be used to wire a lighting circuit and what are they
Two types of wiring system are used for lighting circuits:
two-plate system
three-plate system
The ‘plates’ refers to the number of junctions used in the ceiling rose. The middle junction is called the ‘loop’ and is only used in ‘three plate’ wiring.
66
Here are some points to note about lighting
:
Single pole switches and protective devices must be installed in the line conductor only.
For Edison Screw (ES) lamp holders, the line conductor must be connected to the centre contact of the lamp holder.
Electricians refer to this as correct polarity.
This must be confirmed when inspecting and testing the installation.
This test can be referenced:
OSG 10.3.4 page 121 2022
EGBR 6.3.7 page 122 2022
67
When the rating of a lighting point is not known then we must assume a value of:
100 watts minimum
This can be referenced to Appendix A in your OSG (Table A1) page 137 2022
68
a statement that best describes two plate lighting with regards to wiring is
A cable is taken to the switch first, meaning a neutral would be present at the switch, then to the lamp
69
When installing lighting circuits, switches and protective devices must
be in the line conductor only
70
Why should there be more than one lighting circuit in an installation
To avoid a complete black out in the event of a fault
we should install at least two lighting circuits in the premises.
You can reference this to Regulation 314.1 in BS 7671.
71
What size protective device is generally used for domestic lighting circuits?
6a
72
sockets
BS 7671 Regulation [553.1.201] states that, ‘Every socket-outlet for household and similar use shall be of the shuttered type and, for an AC installation, shall be of a type complying with BS 1363’.
73
13a plugs
These 13A plugs are the most common types of plugs used in domestic properties.
The British Standard is BS 1363 and BS 1363A for more resilient plug tops.
Fuse sizes (to BS 1362) include:
3A
5A
13A
74
industrial type plug and socket outlets
industrial type plug and socket outlets to BS EN 60309 are generally used in areas where there is a higher risk of impact such as garages, workshops and outdoor locations.
They may also be used where the current rating of equipment exceeds
they come in 3 colours
Blue 230v
Yellow 110v
Red 400v
The blue marking identifies a 230V supply.
These sockets come in different physical sizes depending on their maximum load current to include:
16A
32A
63A
75
yellow industrial type plug and socket outlets
The yellow markings on these plug and socket outlets identify a supply voltage of 110V with a centre tapped voltage to earth of 55V.
BS 7671 has requirements for 110V single phase centre tapped 55V to earth supplies, known as reduced low voltage, for portable hand tools and hand lamps when working on construction sites.
76
red industrial type plug and socket outlets
The red markings on these plug and socket outlets identify a three phase supply voltage of 400V between line conductors.
These will be used mainly in commercial and industrial settings to supply three phase, non-fixed equipment.
77
different types of socket circuits
A1
A2
A3
can be found in
OSG table H2.1 page 210 2022
EGBR table 4,2,1 page 72 2022
78
radial circuit A2
In a radial final circuit the cable, comprising of a line, neutral and CPC, ‘radiates’ from the consumer control unit (CCU), looping in and out of each socket outlet until the last outlet is reached and the circuit ends.
Key notes for A2 Radial Socket Circuits
Wired from a 32A circuit breaker (maximum).
Minimum 4mm2 cable (can be difficult to wire in 4mm2)
Can serve a floor area up to 75m2
OSG page 210 table H2.1 A2 2022
79
radial circuit A3
In a radial final circuit the cable, comprising of a line, neutral and CPC, ‘radiates’ from the consumer control unit (CCU), looping in and out of each socket outlet until the last outlet is reached and the circuit ends.
Key notes for A3 Radial Socket Circuits
Wired from a 20A circuit breaker (maximum).
Minimum 2.5mm2 cable (can be difficult to wire in 4mm2)
Can serve a floor area up to 50m2
OSG page 210 table H2.1 A3 2022
80
ring final circuit A1
In a ring final circuit the cable, comprising of a line, neutral and CPC, starts at the consumer control unit (CCU), looping in and out of each socket outlet until the last outlet is reached, and then a cable is brought back to the CCU where it is connected into the same terminals as the outgoing cable.
This has the effect of doubling the cross sectional area of the cable (2.5mm2 becomes 5mm2).
Key notes for A1 Ring Socket Circuits
Wired from a 32A circuit breaker (maximum).
Minimum 2.5mm2 cable (can be difficult to wire in 4mm2)
Can serve a floor area up to 100m2
OSG page 210 table H2.1 A1 2022
81
ring final circuit dangers
The ring final circuit uses 2.5mm2 conductors, which are not compatible with a 32A circuit breaker.
If a cable were to break or a live conductor becomes loose in the back of a socket, the current will no longer be distributed evenly throughout the circuit and the cables are now in danger of overloading.
the break now effectively becoming 2 radial circuits being supplied from a 32 a breaker
82
because of dangers associated with ring final main
that a special test, the continuity of ring final circuit conductors test, must be carried out during the testing process to check that the ring is continuous and there are no breaks.
See OSG 10.3.2 page 115 2022
or EGBR 6.3.5 page 117 2022
83
final circuit spur
A spur is a branch which can be taken from a ring final circuit.
A spur can branch from a circuit by using a junction box (JB) or by connecting directly to an outlet.
A spur may be fused or unfused, however, it is important to consider the following points when installing spurs.
reference to
Appendix 15 in BS 7671 page 555
and can also be found in
EGBR Section 4.2. page 72 2022
84
outdoor sockets
sockets outlets with a rating not exceeding 32A and mobile equipment with a current rating not exceeding 32A for use outdoors, must be protected by an RCD with a rating (IΔn) not exceeding 30mA.
85
outdoor sockets
sockets outlets with a rating not exceeding 32A and mobile equipment with a current rating not exceeding 32A for use outdoors, must be protected by an RCD with a rating (IΔn) not exceeding 30mA.
86
how many socket circuits in an installation
It is generally desirable to install at least two socket circuits in an installation, so that if a fault occurs there will still be some live outlets available in the premises. In domestic properties this usually means one circuit downstairs and one upstairs.
87
how many socket circuits in an installation
It is generally desirable to install at least two socket circuits in an installation, so that if a fault occurs there will still be some live outlets available in the premises. In domestic properties this usually means one circuit downstairs and one upstairs.
88
how many socket circuits in an installation
It is generally desirable to install at least two socket circuits in an installation, so that if a fault occurs there will still be some live outlets available in the premises. In domestic properties this usually means one circuit downstairs and one upstairs.
89
unlimited outlets???
Although socket outlet circuits allow an unlimited number of outlets to be installed within a specified area, the total estimated current demand connected to the circuit should not exceed the rating of the protective device protecting that circuit.
90
kitchen circuit
A separate circuit for the kitchen, where there is likely to be a large number of appliances used simultaneously, should be considered.
91
The number of non-fused spurs that can be installed on a standard A1 ring final circuit is:
unlimited as long as they don’t exceed the number of connected outlets.
The number of spurs are unlimited as long as they don’t exceed the number of connected outlets, but remember to never spur off an unfused spur as this could cause the cable to overload.
92
State the maximum protective device rating for an A2 radial final circuit?
A 32A circuit breaker can be fitted to this circuit. The cable size required is 4mm2.
93
What are the minimum sized live conductors for use on an A3 radial final circuit when wired in twin and earth cable?
An A3 radial final circuit should be wired in 2.5mm² cable and connected to a 20A circuit breaker (maximum).
94
The number of outlets that can be connected to an A2 radial final circuit is unlimited provided that the floor area served does not exceed:
The answer is - 75m2. An A2 radial final circuit should be wired in 4mm² cable and connected to a 32A circuit breaker (maximum).
95
Socket circuits should have:
additional protection by means of an RCD with a IΔn not exceeding 30mA. (See OSG 3.6.2 or EGBR 3.5.1)
96
Spurring from an individual socket more than once is permitted if:
the spurred leg is suitably fused down. When adding multiple sockets from a ring final circuit, it is important to ensure that spurred legs are suitably fused down. This can be achieved by installing a 13A fused connection unit (FCU).
97
a cooker switch
Within 2m of the cooker, but not directly above it, it is recommended a double pole switch be installed to control the supply to the cooker. This switch may or may not incorporate a 13A socket outlet.
98
cooker load and allowances for diversity
Appendix A OSG page 137 2022
It is unlikely that an appliance such as a cooker will ever become fully loaded during normal use.
An assessment of the maximum current demand can be made by using the tables in Appendix A in the OSG.
99
example of calculating cooker demand
example Maximum current demand = 47.83 A
Calculating Maximum Demand Using Table A1 OSG
Remove 10 A from the overall demand which leaves 37.83 A
Find 30% of 37.83 A = 11.35 A
Add 10 A back to this value (11.35 + 10) = 21.35 A
If cooker unit incorporates a socket outlet
If the control unit contained a socket outlet, then 5 amperes should be added to the overall value.
From the previous example 21.35 A + 5 A (for socket) = 26.35 A.
100
The part of the installation that houses the supplier's fuse is referred to as:
the service head
101
The name given to the cables that link the meter to the consumer's control unit are referred to as:
the consumer's tails
102
The double pole device sometimes inserted between the meter and the consumer control unit is called:
an isolator
103
The consumer’s installation starts at:
the outgoing terminals at the meter
Consumers tails
104
The minimum size of the consumer's tails in new installations are:
25mm2
105
the three main earthing systems used in domestic properties in the UK. are
TNS TN-S system, the earthing conductor links the MET to the supply cable sheath
TNCS the earthing conductor links the MET to the PEN supply conductor.
TNT TT system, the earthing conductor links the MET to the dedicated consumer's earth electrode
You can refer to these in Chapter 3 in the Electrician's Guide to the Building Regulations and also Section 2 in the On-Site Guide.
106
What does the letter 'S' stand for in TN-S?
separate
107
What does the letter 'C' stand for in TN-C-S?
Combined
108
The conductor that links the Main Earthing Terminal (MET) of an installation to the means of earthing is known as the:
earthing conductor
109
The conductor that links the Main Earthing Terminal (MET) of an installation to the means of earthing is known as the:
earthing conductor
110
The conductor that links the Main Earthing Terminal (MET) of an installation to the means of earthing is known as the:
earthing conductor
111
In a PME earthing arrangement, which two conductors are combined to provide a return path for an earth fault current?
Neutral & Earth
112
An earthing arrangement where the consumer has to provide their own method of earthing by means of an earth electrode is known as a:
TT earthing arrangement
113
industrial type plug and socket outlets
come in 3 colours
What are they
And
What voltage
Blue 230v
Yellow 110v
Red 400v
114
Protective bonding must have what label
A durable label to BS 951 with the words 'Safety Electrical Connection – Do Not Remove' shall be permanently fixed in a visible position at or near:
(i) the point of connection of every earthing conductor to an earth electrode, and
(ii) the point of connection of every bonding conductor to an extraneous-conductive-part, and
(iii) the main earthing terminal, where separate from main switchgear.
115
BS 951 bonding clamps are only to be fastened to
BS 951 bonding clamps are only to be fastened to copper or steel pipework.
They are **NOT** suitable for lead or steel wire armour (SWA).
116
E14 E15 & E16 are what colour & for use in what conditions
E14 clamps are coloured red and are for dry conditions only
E15 clamps are coloured blue and are for dry or damp conditions
E16 clamps are coloured green and are for dry, damp or corrosive conditions.
These clamps allow connection to larger cross sectional area pipework - usually in excess of 16mm2
117
Supplementary bonding
Supplementary bonding 'supplements' the main protective bonding and is often required in special locations or installations
118
Supplementary bonding is found in what BS & what part
Supplementary bonding is required in some of the locations and installations falling within the scope of
Part 7 of BS 7671.
119
For additional information regarding supplementary bonding, refer to
the special locations in Part 7 in BS 7671.
Section 4 in the On-Site Guide contains information on Earthing and Bonding.
The Electrician's Guide to the Building Regulations contains information on special locations in Chapter 5 and Earthing and Bonding in Chapter 3.
120
For additional information regarding supplementary bonding, refer to
the special locations in Part 7 in BS 7671.
Section 4 in the On-Site Guide contains information on Earthing and Bonding.
The Electrician's Guide to the Building Regulations contains information on special locations in Chapter 5 and Earthing and Bonding in Chapter 3.
121
For additional information regarding supplementary bonding, refer to
the special locations in Part 7 in BS 7671.
Section 4 in the On-Site Guide contains information on Earthing and Bonding.
The Electrician's Guide to the Building Regulations contains information on special locations in Chapter 5 and Earthing and Bonding in Chapter 3.
122
Earthing and bonding conductors
Earthing and bonding conductors will need to be correctly sized when installing and will need to be checked during an electrical installation condition report (EICR)
123
Earthing and bonding conductor sizing for TN-S and TN-C-S supplies can be found in
Table 3.3.2a/b can be found in Chapter 3 in the Electrician's Guide to the Bulding Regulations
.
In the On-Site Guide it's Table 4.4(i)/(ii) and can be found in Section 4.
124
fot TT see
Table 3.3.2d - Electrician's Guide to the Building Regulations
Table 4.4 (iii) - On-Site Guide
125
for References on Earthing and Bonding conductors
refer to Chapter 3 in the Electrician's Guide to the Building Regulations
and
Section 4 in the On-Site Guide for more information on Earthing and Bonding conductors.
126
description of an exposed-conductive-part
Conductive part of equipment which can be touched and which is not normally live, but which can become live under fault conditions.
127
example of an extraneous-conductive-part
Structural steel
128
What is the correct size of mechanically protected supplementary bonding when connecting an exposed-conductive part to an extraneous-conductive part when the circuit protective conductor csa is 4mm²?
The answer is - 2.5mm² (Table 3.3.3 Electrician's guide to the Building regulations page 56 2022
and
Table 4.6 in the On-Site Guide).page 58 2022
129
the following is an example of an exposed-conductive-part
A satin chrome socket outlet
130
What is the wording on a BS 951 bonding clamp label
Safety Electrical Connection - Do Not Remove
131
bonding matches
Main Protective Bonding - Connects the MET to extraneous conductive parts.
Circuit Protective Conductor = Connects the MET to exposed conductive parts.
Earthing Conductor = Connects the MET to the source of earth.
132
impedance is measured in what and what letter represents it mathematically
OHMS and Z
133
Ze
The part of the earth fault loop impedance path that is 'external' to the installation.
134
R1+R2
The resistance of the line and CPC on a circuit within the installation.
135
Zs
The total (or sum) of Ze and R1 + R2. Written as:
Zs = Ze + (R1 + R2)
CPC
136
CPC
circuit protective conductor (R2)
Forms part of the earth fault loop path
MET
137
MET
main earthing terminal (MET)
circuit protective conductor. (R2)
Forms part of the earth fault loop path
138
Earthing Conductor
Links the MET to the means of earthing.
Supply
139
Supply Transformer
Source of the electrical supply to the property
140
Line Conductor
Forms part of the earth fault loop (R1)
141
Protective Device
Will disconnect the circuit in the event of a fault.
142
Protective devices
During earth fault conditions a protective device (fuse, circuit breaker, RCBO) must disconnect within a specified time to comply with BS 7671.
In order for a protective device to disconnect, a sufficient amount of current must flow to earth.
A lower value of Zs means more current will flow during a fault, causing the protective device to operate.
143
Tables of maximum values of **Zs**
(The total (or sum) of Ze and R1 + R2)
Section 4 **TABLE 4.1.2a** in the Electrician's Guide to the Bulding Regulations page 67 2022.
Appendix B **TABLE B6** in the On-Site Guide. page 139 2022
Part 4 in BS 7671. page 59
144
Maximum values of **Ze** (external earth fault loop impedance)
must be determined to ensure there is a continuous return path to the supply transformer.
The maximum stated values commonly quoted by distributors are:
TN-S = 0.8Ω
TN-C-S = 0.35Ω
TT = 200Ω
145
**Zs** information
When **Zs** values comply with the values in the tables, then we can be sure that protective devices will operate and disconnect a circuit within the time stated in BS 7671.
Section 4 **TABLE 4.1.2a** in the Electrician's Guide to the Bulding Regulations page 67 2022.
Appendix B **TABLE B6** in the On-Site Guide. page 139 2022
Part 4 in BS 7671. page 59
146
**Ze** information
Values of **Ze** must comply with the values given by the distributors. If values of Ze exceed these for TN systems, then the supply company must be informed.
TN-S = 0.8Ω
TN-C-S = 0.35Ω
TT = 200Ω
147
**Zs**
Values of **Zs** in a TT system will always be greater than the values in these tables and disconnection times will not be met.
For this reason, extra safety measures such as supplementary bonding and use of RCDs may be required.
Section 4 **TABLE 4.1.2a** in the Electrician's Guide to the Bulding Regulations page 67 2022.
Appendix B **TABLE B6** in the On-Site Guide. page 139 2022
Part 4 in BS 7671. page 59
148
A high value of **Zs** will have what effect on a circuit?
The current will decrease and may **NOT**be sufficient to cause operation of the protective device
(Ohm’s law - Higher resistance means lower current for a constant voltage).
149
What does a fault of negligible impedance mean?
There is virtually no resistance between conductors. Impedance is another word for resistance in AC circuits.
Negligible means small or insignificant. When a fault of negligible impedance occurs, a high fault current will flow.
150
What is the maximum earth fault loop impedance (Zs), for a 40A Type B BS EN 61009 RCBO, used to protect a shower circuit in a domestic property?
0.88Ω -
See Table 4.1.2a page 69 2022
in the Electrician's Guide to the Building Regulations
and
Table B6 page 145 2022
in the On-Site Guide
151
What is the maximum Zs for a 20A BS 88-3 fuse, to ensure the correct disconnection time, when protecting a radial final circuit not exceeding 32A?
1.55 Ω -
See Table 4.1.2c page 71 2022
in the Electrician's Guide to the Building Regulations
and
Table B4(i) page 143 2022
in the On-Site Guide.
152
Zs = Ze + (R1+R2)
Zs = Ze + (R1+R2)
See Section 6 in the Electrician's Guide to the Building Regulations (6.3.9 - Earth Fault Loop Impedance) page 124 2022
and
Appendix I in the On-Site Guide. page 217 2022
153
What is the minimum size of the main protective bonding conductors when the incoming line conductor is 25mm² in a TN-S system?
10mm² (Table 3.3.2a in Chapter 3 page 53 in the Electrician's Guide to the Building Regulations
and
Table 4.4 (i) in Section 4 in the On-Site Guide). Page 55
154
What is the minimum size of meter tails allowed in a domestic property?
25mm² (3.1.3, Chapter 3, Consumer's tails, the Electrician's Guide to the Building Regulations and 2.2.3.1, Section 2 in the On-Site Guide).
155
What is the maximum Zs for a 16A Type C BS EN 60898 circuit breaker when installed on an immersion heater circuit?
1.09 Ω (Table 4.1.2b, Chapter 4 in the Electrician's Guide to the Building Regulations page 70 2022
and
1.10 Ω in
Table B6 in Appendix B in the On-Site Guide).page 145 2022
156
In which earthing arrangement would you find a PEN conductor?
TN-C-S (3.2.1 - Section 3 in the Electrician's Guide to the Building Regulations) page 48
further information BS7671 table 54.8 page 205 2022
157
What is the correct size of a supplementary bonding conductor, not mechanically protected, when connecting an exposed-conductive part to an extraneous-conductive part, where the circuit protective conductor csa is 4mm²?
4mm² (Table 3.3.3, Chapter 3 in the Electrician's Guide to the Building Regulations page 56
and
Table 4.6, Section 4 in the On-Site Guide) page 58
158
The maximum fuse size fitted by the supply company in domestic properties is:
100 A (See 3.2 in Electrician's Guide to the Building Regs page 47 the guide assumes (d)
and
1.1 in the On-Site Guide) page 13 the guide is restricted to installations (c)
159
In a TT system, what is the correct size of the copper earthing conductor if it is being protected against corrosion and buried
16mm²
(Table 3.3.2d, Chapter 3 in the Electrician's Guide to the Building Regulations page 54
and
Table 4.4 (iii) in the On-Site Guide)page 56.
160
In a TT system, what is the correct size of the copper earthing conductor if it is being protected against corrosion and NOT buried
4mm²
(Table 3.3.2d, Chapter 3 in the Electrician's Guide to the Building Regulations page 54
and
Table 4.4 (iii) in the On-Site Guide)page 56.
161
The frequency of the supply in the UK is:
50 Hz. Frequency is measured in Hertz (Hz = cycles per second)
(See 3.2 in Electrician's Guide to the Building Regs page 47 the guide assumes (a)
and
1.1 in the On-Site Guide)
162
The frequency of the supply in the UK is:
50 Hz. Frequency is measured in Hertz (Hz = cycles per second)
(See 3.2 in Electrician's Guide to the Building Regs page 47 the guide assumes (a)
and
1.1 in the On-Site Guide)
page 13 this guide is restricted to installations 313.1 (a)
163
“A dangerous potential with respect to earth” is referring to a measure of:
Voltage. (Voltage is a measure of 'potential difference').
164
The maximum value of Ze quoted by distributors for a TN-C-S system is:
0.35 Ω (3.2.1, Chapter 3 in the Electrician's Guide to the Building Regulations page 47 (a)
and
1.1 in the On-Site Guide) page 13 NOTE (d)
165
The cartridge fuse being fitted in new premises and upgrades by supply companies is a:
BS 88-3 (can be found in Section 1 in the On-Site Guide).
166
In a TT system, what is the correct size of the copper earthing conductor if it is unprotected and NOT buried
4mm2
(Table 3.3.2d, Chapter 3 in the Electrician's Guide to the Building Regulations page 54
and
Table 4.4 (iii) in the On-Site Guide)page 56.
167
In a TT system, what is the correct size of the copper earthing conductor if it is protected against corrosion and mechanical damage and NOT buried
2.5mm2
(Table 3.3.2d, Chapter 3 in the Electrician's Guide to the Building Regulations page 54
and
Table 4.4 (iii) in the On-Site Guide)page 56.
168
1864
Fuses
A variety of wire or foil fusible elements were in use to protect telegraph cables and lightning installations as early as 1864.
A fuse was patented by Thomas Edison in 1890 as part of his electric distribution system.
169
1930s
Circuit breakers
Circuit breakers for residential panels were available in the 1930s.
They began to replace fuses in domestic properties starting in the 1950s and most domestic properties had circuit breakers installed by the mid-1970s.
Early circuit breakers were manufactured to BS 3871 while modern day circuit breakers are manufactured to BS EN 60898.
170
1956/7
The Residual Current Device (RCD)
Like other inventions, RCDs were invented by different people, in different places, at different times!
The first person to be credited with developing what was called a 'Ground Fault Circuit Interrupter' appears to have been Austrian physicist Dr Gottfried Biegelmeier (1924–2007).
He was granted a patent in 1956/7.
RCD is a generic term which covers many devices, including the RCCB (Residual Current Circuit Breaker without overcurrent protection) and the RCBO (Residual Current Circuit Breaker with Overcurrent protection).
171
2009
The Residual Current Circuit Breaker with Overcurrent protection (RCBO)
Eaton-Moeller promoted their first digital RCCB and RCBO in 2009.
The RCBO combines the functions of a circuit breaker with that of an RCD.
172
2016
The Arc Fault Detection Device (AFDD)
Designed to detect electrical arcing in an electrical system which can lead to overheating and fires.
The latest AFDDs are combined with an RCBO for all-round protection of circuits and equipment.
173
A cable rated at 37A is carrying a current of 50A. This is referred to as:
overload
174
A line to neutral fault is commonly referred to as:
short circuit
175
When a live conductor is loose in a terminal and the current jumps from the conductor to the terminal. This is known as:
arcing
176
An overcurrent occurring in a circuit which is electrically sound' is the definition of:
an overload
177
Which devices will detect small earth fault currents?
RCDs
(Fuses and circuit breakers require large fault currents in excess of their current rating to disconnect a circuit)
178
enclosed fuse ratings to their correct colour.
5A White
15A Blue
20A Yellow
30A Red
45A Green
179
Which type of fuse (BS number?) would most commonly be found at the origin of a new domestic installation?
BS 88-3
180
fuse containing silica sand
BS 88-2
181
Fuse BS 1362. will fit in a ?
Plug
It fits plugs
182
Circuit breakers are manufactured to BS
BS EN 60898
183
Which component part of a circuit breaker protects against overloads
Bi-metallic strip
(Usually made from copper and iron, the strip expands due to the heat created by an overload current. As copper expands faster than iron, the bi-metallic strip bends and trips the circuit breaker.)
184
faults that circuit breakers protect against
overloads,
overcurrents
large earth fault currents.
(Small earth fault current levels that are dangerous to people and livestock - 30 to 80mA for example - are too low to operate circuit breakers.)
185
What would be a typical application where we would use a Type D circuit breaker
On an X-ray machine
(Table 7.2.7(ii) in the On-Site Guide)page 90 2022
186
What would be a typical application where we would use a Type B circuit breaker
Domestic & Commerciale
(Table 7.2.7(ii) in the On-Site Guide)page 90 2022
187
What would be a typical application where we would use a Type C circuit breaker
Commercial & Industrial
(Table 7.2.7(ii) in the On-Site Guide)page 90 2022
188
RCD No fault condition
In a healthy circuit, the residual current between line and neutral conductors is balanced.
189
RCD Fault condition
When an imbalance is detected between line and neutral conductors then the device will operate and disconnect the current flow in the circuit.
OSG section 11 page 127
190
RCD's
RCDs give protection against earth faults only. They do not protect against overloads or overcurrents caused by short circuits
191
RCBO information
The RCBO combines the functions of a circuit breaker with that of an RCD and is now the number one choice for many electricians when installing circuits in domestic properties.
192
RCBO further information
RCBOs are designed to protect a single circuit. They give protection against overloads, overcurrents caused by short circuits and earth faults.
193
Disadvantage of split load consumer units (2 individual RCDs alongside circuit breakers)
If an RCD that is protecting several circuits should trip, then we lose power to all the protected circuits.
194
RCBOs - advantages
Faults occurring in a circuit will only disconnect the RCBO protecting that circuit. All other circuits will be unaffected
195
An RCD is used to provide protection against these faults?
Earth fault
(RCDs only operate when there is an earth fault.)
196
When a 30mA RCD is tested at 1 times its operating current, it should trip in less than
300ms
11.5, Section 11 in the On-Site Guide page129 2022
and
Table 6.4, Chapter 6 in the page 127 2022 Electrician's Guide to the Building Regulations.
197
An RCBO gives protection against the following faults
Overcurrents caused by short circuits
Earth faults
Overload
198
protector matches
IΔn - RCD rated residual operating current
BS EN 61008 - Standard for a general purpose RCD
BS 7288 - RCD protected socket outlet
Toroid - Component part of an RCD
BS EN 61009 - Standard for a general purpose RCBO
199
Examples of properties requiring AFDDs to BS EN 62606
Higher Risk Residential Buildings - such as high rise flats housing many people
Houses in Multiple Occupation
Purpose-built student accommodation
Care homes
see EGBR page 42 section 2 regulation 421.1.7
200
An arc limited to one conductor is called a ________ arc
'series' arc, although some sources use the word 'serial'
201
AFDDs are manufactured to:
BS EN 62606 -
OSG 3.8, page 49 2022
EGBR 2.4.1. page 42
(See also Regulations 421.1.7 and 532.6 in BS 7671.)
202
An arc between conductors is called a ________ arc
'parallel' arc
203
The current version of BS 7671 require AFDDs to be installed on circuits containing socket outlets in
Houses in Multiple Occupation (HMO),
Care homes, 
Higher Risk Residential Buildings (HRRB)
Purpose-built student accommodation.
OSG 3.8, page 49
EGBR 2.4.1 page 42
204
which part of a circuit breaker will disconnect the circuit quickly in the event of a large earth fault or short circuit current
magnetic coil and plunger
205
The type of sand used in a
BS 88-2 fuse is called
Silica
(this type of sand melts into glass and quenches the arc that may result when the fuse element blows as a result of a large fault current.)
206
An arc occurring between two conductors is
parallel arc
207
A circuit condition in which current flows through an abnormal or unintended path' is the definition of
a fault (Definitions in BS 7671)
208
BS 88-2 fuses are classed as HBC fuses. What do these initials stand for
High breaking capacity
(also HRC - High rupturing capacity). They are able to safely break high fault currents.
209
An RCD works by monitoring the residual current between which conductors?
Line and Neutral
(See RCD section in the On-Site Guide.) If current is escaping to earth, there will be an imbalance between line and neutral and the RCD will trip the circuit.
210
RCDs installed for 'additional protection' against electric shock are rated no higher than:
30mA.
As fault currents in excess of 50mA can be fatal, then RCDs rated no higher than 30mA are installed for 'additional protection.'
211
What is the BS EN number for RCBO
BS EN 61009 (This is an RCBO and is manufactured to BS EN 61009)
212
The maximum size fuse that can be fitted in a BS 1363 plug top is:
13A (This is the maximum rating of a BS 1362 cartridge fuse.)
213
Referencing your On-Site Guide, what circuit breaker would a cooker circuit require in a domestic property.
Type B circuit breaker
Most circuits in domestic properties will use a type B circuit breaker
214
BS 7671 Regulation [522.6.202] states that “a cable installed in a wall or partition must”:
a) be buried at least 50 mm from the surface, or
b) be protected by a 30mA RCD and installed in prescribed ”zones”
c) have earthed armouring or an earthed metal sheath, or
d) be enclosed in earthed steel conduit or trunking, or
e) be provided with mechanical protection sufficient to prevent penetration of the cable by nails, screws and the like or
f) form part of a SELV or PELV circuit.
215
What is the minimum depth of hole (in mm) from the top or bottom of a joist where a cable can be installed?
50 mm
Permitted cable routes
Please refer to your On-Site Guide (OSG) or your Electrician's Guide to the Building Regulations (EGBR).
OSG - Section 7 (7.3 & 7.4) page 91
EGBR - Chapter 2 (2.3) and Chapter 10 (10.1.1)
216
At what distance should gas installation pipes be spaced from electricity supply equipment?
150mm
(Section 7.4.3 in OSG) page 94
217
Earthing and Bonding
A permanent label to BS 951 must be permanently fixed in a visible position at or near the point of connection of:
(a) every earthing conductor to an earth electrode;
(b) every protective bonding conductor to extraneous-conductive-parts;
and
(c) at the main earth terminal (MET), where it is not part of the main switchgear.
218
Solar PV
All junction boxes
(PV generator and PV array boxes) must carry a warning label indicating that parts inside the boxes may still be live after isolation from the PV convertor.
Each point of access to live parts on the DC side, such as distribution boards and combiner boxes, shall have a permanent warning notice indicating that live parts may be still energized after isolation.
The labels must have the wording shown here
219
RCD testing
Where an installation incorporates an RCD, a notice must be fixed in a permanent position at or near the origin of the installation.
The requirements of Regulation 514.12.2 need not be applied for domestic (household) premises or similar installations where:
– the fixing of the notice is not reasonably practicable; for example, where there is insufficient room or the location of the notice is deemed unlikely to be beneficial; and
– an Electrical Installation Certificate, complete with Guidance and Instruction for Recipients, as detailed in Appendix 6 of BS 7671, has been issued to the person ordering the work.
NOTE: Examples and dimensions of labels are provided in Appendix 11 of BS 7671.
220
Periodic Inspection and Testing
A notice of durable material indelibly marked, with the words shown here, must be fixed in a prominent position at or near the origin of every installation. The person carrying out the initial verification must complete the notice and it must be updated after each periodic inspection.
The requirements of Regulation 514.12.1 need not be applied for domestic (household) premises or similar installations where:
– the fixing of the notice is not reasonably practicable; for example, where there is insufficient room or the location of the notice is deemed unlikely to be beneficial; and
– an Electrical Installation Certificate, complete with Guidance and Instruction for Recipients, as detailed in Appendix 6 of BS 7671, has been issued to the person ordering the work.
NOTE: Examples and dimensions of labels are provided in Appendix 11 of BS 7671.
221
Non-standard colours
If additions or alterations have been made to an installation, but there is also wiring in the earlier colours, a warning notice may have been affixed at or near the appropriate distribution board using the wording shown here.
222
Alternative supplies
Where an installation includes additional or alternative supplies, such as a PV installation, which is used as an additional source of supply in parallel with another source, normally the distributor's supply, warning notices must be affixed at the following locations in the installation:
(a) at the origin of the installation;
(b) at the meter position, if remote from the origin;
(c) at the consumer unit or distribution board to which the additional or alternative supply is connected; and
(d) at all points of isolation of all sources of supply.
The warning notice must use the wording shown here.
223
Where would a durable label to BS 951 be found
At the connection point for main protective bonding
224
How often should an RCD be functionally tested
Every 6 months.
225
In which scenario would you find multiple electrical supplies?
Where there are solar panels installed in parallel with the supply.
226
When can an RCD testing label be omitted
Where there is insufficient room,
Where the location is unlikely to be beneficial
Where an Electrical Installation Certificate complete with Guidance for Recipients has been issued
227
Basic protection and IP codes
A fundamental principal of BS 7671 is to provide for the safety of people, animals and property against the dangers and damages which may arise from the use of electricity.
This is why electrical equipment must meet certain IP ratings.
IP codes (or 'ratings') can be referenced in Appendix L in the OSG and Table 5.3.1 in Chapter 5 of the EGBR
228
Protection for safety
Chapter 13 in BS 7671 states that in electrical installations, risk of injury may result from:
Shock currents
Excessive temperatures likely to cause burn, fires etc.
Ignition of a potentially explosive atmosphere
Undervoltages, overvoltages and electromagnetic disturbances
Mechanical movement of electrically actuated equipment
Power supply interruptions
Arcing or burning, likely to cause blinding effects, excess pressure and / or toxic gases.
229
Two important terms to reduce the risk of electric shock as seen in
BS 7671 Section 131.2 are:
Basic protection
Fault protection
'Basic protection can be achieved by preventing a current from passing through the body of either a person or an animal.'
230
Ingress of solids and liquids
An installation must be protected against any ingress of solids objects or liquids that could cause danger and/or damage to the equipment.
All installed equipment must have an appropriate IP rating for the nature of the ‘external influence’.
This could range from protection from fine dust to a human hand or finger, to protection against ingress of water.
231
requirements of BS 7671 regarding the level or protections against the ingress of solids and liquids for electrical equipment.
IP = Ingress or International protection.
First numeral = Protection against solids e.g. IP2X is protection against a 12.5mm solid foreign object.
Second numeral = Protection against liquids e.g. IPX2 is protection against vertically falling water drops up to 15° angle from vertical.
Additional letter = Protection against a specific object e.g. IPXXB is protection against access of a ‘standard finger’.
An ‘X’ = Not rated.
232
The minimum IP rating for the front, sides or bottom of an enclosure as specified in BS 7671 is:
IP2X (or IPXXB). BS 7671 Section 416
233
The minimum IP rating for the top surface of an enclosure as specified in BS 7671 is:
IPXXD (or IP4X). BS 7671 Section 416
234
the following IP codes gives protection against water
IPX4. The second digit in the code is the rating for protection against ingress of water. In this case it is water splashed from any direction. (Appendix L OSG)
235
An enclosure protected from dust would have an IP code of:
IP6X. The first digit in the code is giving a rating of protection against ingress of solids. A higher number means it has a higher degree of protection. IP6X means it is 'dust tight' whilst IP1X would give protection against a 50mm solid object
236
the following code is specifically giving protection against a human finger?
IPXXB. In this case there are no digits, however, there is an additional letter. IPXXB gives protection specifically against a human finger.
237
the following code is specifically giving protection against a human finger?
IPXXB. In this case there are no digits, however, there is an additional letter. IPXXB gives protection specifically against a human finger.
238
special locations
All ‘special locations’ are defined as areas where, due to the nature of the external influence, there is greater risk of electric shock.
The focus in this lesson will mainly be on domestic properties where shower rooms and bathrooms are the 'special location'.
We'll briefly look at the special locations covered by BS 7671
239
Special locations further
Special installations or locations, are those installations or locations where there are additional requirements.
The additional requirements, for example, might be to protect against environmental conditions such as water, steam or impact; and
To provide adequate protection against electric shock in situations where the body is more susceptible i.e., without clothes or immersed in water, or in contact with Earth.
240
greater than average risk of electric shock in locations such as:
Zones of baths or showers.
Rooms containing Swimming pools.
Rooms containing Hot air saunas.
BS 7671 Part 7 contains a full list of installations and locations with special requirements.
In these locations we may consider additional requirements such as:
RCD protection
IP requirements
Supplementary bonding
All special installations and locations will have specific requirements and it is important to make reference to these Sections in BS 7671 when installing any circuits, equipment or accessories in these locations.
241
Locations containing a bath or shower
All low voltage circuits serving the location must be protected by a 30 mA RCD.
All low voltage circuits passing through zones 1 and 2, but not serving the location, must be protected by a 30 mA RCD.
Socket-outlets, e.g. BS 1363, are not allowed within 2.5 metres of zone 1 (the edge of the bath or shower basin).
Protection against ingress of water is specified for equipment within the zones.
There are restrictions as to where appliances, switchgear and wiring accessories may be installed.
Refer to Section 8 in the OSG and Chapter 5 in the EGBR for additional requirements and excellent pictures of zones in bathrooms and rooms containing a shower.
242
Special locations in BS 7671
You'll find all the special installations and locations in Part 7 in BS 7671. Here's the Section references:
PART 7 - SPECIAL INSTALLATIONS OR LOCATIONS
CONTENTS
700 GENERAL
701 LOCATIONS CONTAINING A BATH OR SHOWER
702 SWIMMING POOLS AND OTHER BASINS
703 ROOMS AND CABINS CONTAINING SAUNA HEATERS
704 CONSTRUCTION AND DEMOLITION SITE INSTALLATIONS
705 AGRICULTURAL AND HORTICULTURAL PREMISES
706 CONDUCTING LOCATIONS WITH RESTRICTED MOVEMENT
708 ELECTRICAL INSTALLATIONS IN CARAVAN / CAMPING PARKS AND SIMILAR LOCATIONS
709 MARINAS AND SIMILAR LOCATIONS
710 MEDICAL LOCATIONS
711 EXHIBITIONS, SHOWS AND STANDS
712 SOLAR PHOTOVOLTAIC (PV) POWER SUPPLY SYSTEMS
714 OUTDOOR LIGHTING INSTALLATIONS
715 EXTRA-LOW VOLTAGE LIGHTING INSTALLATIONS
717 MOBILE OR TRANSPORTABLE UNITS
721 ELECTRICAL INSTALLATIONS IN CARAVANS AND MOTOR CARAVANS
722 ELECTRIC VEHICLE CHARGING INSTALLATIONS
729 OPERATING AND MAINTENANCE GANGWAYS
730 ONSHORE UNITS OF ELECTRICAL SHORE CONNECTIONS FOR INLAND NAVIGATION VESSELS
740 TEMPORARY ELECTRICAL INSTALLATIONS FOR STRUCTURES, AMUSEMENT DEVICES AND BOOTHS AT FAIRGROUNDS, AMUSEMENT PARKS AND CIRCUSES
753 HEATING CABLES AND EMBEDDED HEATING SYSTEMS
243
In a location containing a bath or shower, zone 0 is:
inside the bath or shower basin
244
When installing light switches within zone 2 in a bathroom, the installer must use:
an appropriate pull cord switch installed outside the zone (the cord is allowed to be in zones 1 or 2, but the switch must be outside the zones - see Figure 5.3.1a).
245
In a location containing a bath or shower, zone 1 is:
directly above the bath or shower basin.
246
A special location can be defined as any area:
where there is a greater than average risk of electrocution
247
In a location containing a bath or shower, zone 2 is:
Up to 600mm (0.6m) from the edge of zone 1
248
A socket outlet can be installed in a location containing a bath or a shower provided that:
it is positioned at a distance of 2.5m from zone 1
249
Regulation B1 of the Building Regulations 2010 requires appropriate provision for early warning of fire. State the minimum grade of fire detection and fire alarm system recommended for a new dwelling.
D - 10.2.2 Early warning of fire (note (a) Grade D Category LD3) See also Appendix D 1.3 'All new dwellings.....Grade D Category LD3'
250
Which Approved Document applies to site preparation and moisture
C - 1.2.2 Approved documents
251
Within a block of residential flats, which electrical installation would Approved Document P not apply to:
power to lifts - 1.3.2 Scope of Part P. "Part P does not apply to electrical installations:...(b) that supply the power to lifts in blocks of flats...."
251
Within a block of residential flats, which electrical installation would Approved Document P not apply to:
power to lifts - 1.3.2 Scope of Part P. "Part P does not apply to electrical installations:...(b) that supply the power to lifts in blocks of flats...."
252
A ring final circuit in a lounge is extended to include one additional socket outlet which is positioned on an exterior surface of the dwelling. The installer must
Carry out the correct Inspecting and Testing procedure as per BS 7671 and issue a Minor Works certificate to the client as this is non-notifiable work - 1.6 Non-notifiable work, note (c)
253
A new consumer unit & main protective bonding conductors are to be installed. Building control should be notified of:
Installation of the consumer unit only - 1.5.2 Notifiable work
254
The minimum amount of energy efficient lighting locations for a new dwelling having 8 rooms is:
6 - 10.6.1 Fixed internal lighting. Note (a) "in the areas affected by the building work, provide low-energy light fittings that number not less than three-quarters (75%) of all the light fittings......" 75% of 8 = 6
255
Other than BS 5839-6, where can guidance on the installation of fire detection and fire alarm systems for dwellings be found in?
Approved Document B - 1.2.2 Approved documents. See also 10.2.2 Early warning of fire (BS 5839-6 is referred to)
256
example of Minor work is:
Adding a new socket outlet on a ring final circuit in a bedroom - 1.6 Non-notifiable work note (a)
257
Socket outlets installed back to back on a lath and plaster wall should be avoided because:
Sound and fire qualities are diminished - The best reference for fire is 10.2.3 Spread of fire and if you look at 10.4 Resistance to passage of sound, you'll see in note (a) towards the end of the section 'sockets must be staggered on opposite sides of the separating wall.....not back to back'.
258
Which of the following is not a recognised method of establishing the fitness for purpose of materials for use?
Supplier’s recommendations - This is not very clear in the book but the closest reference is 2.2 Selection of materials, and is assuming some previous knowledge and experience. Hopefully you arrived at the right answer by a process of elimination!
259
What is the maximum fine for breach of the Building Regulations 2010?
Unlimited - This is not mentioned in the guide so make a note! (Use a tab)
260
Which of the following is not considered an adequate means of assessing the validity of an item of equipment?
On line market place seller - This is not very clear in the book but the closest reference is 2.2.2 Compliance with equipment standards under 2.2 Selection of materials, and is assuming some previous knowledge and experience. Hopefully you arrived at the right answer by a process of elimination!
261
Where could information about structural floor timbers be found as referred to in Approved Document A Section 2B?
In timber tables produced by TRADA - This is mentioned in Approved Document A but NOT in the Electrician's guide to the Building Regulations so make a note of this!
262
Which of these materials would not be classed as fire retardant?
Medium density fibreboard (MDF) - This is made from wood chips. Again, not in the book but assumes some prior knowledge. Make a note!
263
How can past experience be used as a method of assessing material as fit for use?
The material can be shown by its usage to be capable of performing the function for which it was intended - 2.2 Selection of materials. See 2.2.1 note (iii) "...used or fixed so as to adequately perform the functions for which they are designed...."
264
Within a block of serviced residential flats, which specialist electrical installation would Document P not apply to?
HV cable networks - Fig 1.3.1 See 'Limits on application' - You'll see that Part P only covers 'low' or 'extra-low' voltage installations
265
An electrical service trunking penetrates a floor separating dwellings in a block of flats. Which approved document would need to be referred to in order to comply with the Building Regulations?
Approved Document B - 1.2.2 Approved documents. See also 10.2.3 Spread of fire and Appendix D, Section 7: Protection of openings and fire-stopping (7.2)
266
An electrically skilled person employed by an assessed enterprise and working on their behalf:
Need not inform the building control prior to undertaking any electrical work - 1.4.1 Prior notification
267
The requirements of the Building Regulations can be found in:
Schedule 1 and they are in 14 parts - 1.2.1 The Building Regulations 2010. "Regulation 4 of the Building Regulations 2010 requires building work... to comply with the performance requirements listed in Schedule 1, under the 14 Parts A to P."
268
The requirements of the Building Regulations can be found in:
Schedule 1 and they are in 14 parts - 1.2.1 The Building Regulations 2010. "Regulation 4 of the Building Regulations 2010 requires building work... to comply with the performance requirements listed in Schedule 1, under the 14 Parts A to P."
269
What is R1and R2
line and CPC
