2330 Level 2 Unit 205 Installation (Buildings And Structures)

Explanation
The Electricity at Work Regulations 1989 (EAW Regulations) came into force on 1 April 1990. This circular aims to highlight the key issues on inspection and enforcement for inspectors. It is not comprehensive. http://www.hse.gov.uk/lau/lacs/19-3.htm

Explanation
British Standard BS7671 (also known as the IEE Wiring Regulations – 17th Edition) gives the requirements for electrical installations; the requirements for joints and terminations are contained in Section 526. The performance of mechanical and compression joints is the subject of BS EN 61238 (or BS 4579 for old joints); the tensile strength of such joints is specified as a percentage of that of the cables which are being joined. http://www.hse.gov.uk/lau/lacs/18-1.htm

Explanation
Persons and equipment within buildings can be at risk from lightning currents and associated
voltages which may be conducted into the building as a consequence of a lightning strike to the
building or associated services. Some equipment (e.g. electronic equipment, including
computers) is especially susceptible to damage from over voltages in the electricity supply caused
by lightning and such damage may occur even when the lightning strike is remote from the
building (e.g. from a surge conducted into the building via the electricity supply).
Measures should to be taken to protect persons and equipment within buildings from the effects
of lightning

Explanation
BS EN Standard
European technical standard as adopted in the UK. BS EN standards often supersede pre-existent national technical standards BS (British Standards).

Explanation
Engineering can be a very broad term. It stems from the Latin ingenerare, meaning "to create".Because this could apply to everything that humans create, it is given a narrower definition in the context of technical drawing. Engineering drawings generally deal with mechanical engineered items, such as manufactured parts and equipment.

Explanation
Working Drawings and Building RegsBuilding Control is the local authority service that is responsible for administrating and enforcing the Building Regulations. The Building Regulation's minimum technical requirements are explained by a series of government issued approved documents which cover the safe structure of buildings, fire safety, hygiene, drainage and waste disposal, efficient use of fuel and power, access to buildings and the installation of windows and doors, as well as other controlled fittings and works. We will design a fully detailed Building regulations drawing to the specification required by the authorities.

Working drawings and written specifications give the opportunity to the client to tailor their proposed work, this can include floor finishes, types of window frames, the position of power sockets.

We are here to advise on all aspects, after your design is finalised the specification and working drawings are ready for our builders to work from, or ready to be sent to tender to a builder of your choice. http://www.homedesignconsultants.co.uk/servicescontent-WorkingDrawings.php

Explanation
Drawing to Scale

The whole idea behind creating scale drawings is to allow the drafter to create a drawing which is proportionately the same as the artifact it represents. Using a measuring device called a scale, we can create accurate drawings of both very large objects or very small objects and fit either on a standard size piece of paper.

2:1
Pronounced "Two to One"
DOUBLE SIZE :2 millimeters on paper =1 millimeter on the artifact
The drawing is twice as large as the artifact.

1:1
Pronounced "One to One"
FULL SIZE: 1 millimeter on paper =1 millimeter on the artifact
The drawing is the exact same size as the artifact.

1:2
Pronounced "One to Two"
HALF SIZE : 1 millimeter on paper =2 millimeters on the artifact
The drawing is half the size of the artifact.

1:4
Pronounced "One to Four"
QUARTER SIZE or 1 millimeter on paper= 4 millimeters on the drawing.
The drawing is one quarter the size of the artifact. http://www.archaeologica.org/Drawing%20to%20Scale.htm

Explanation
The contracts manager would use work sheets and time sheets to check the ongoing progress of a contract. Work sheets provide a detailed breakdown of the tasks and activities completed, allowing the manager to track the completion of different stages of the contract. Time sheets, on the other hand, record the amount of time spent on each task, helping the manager monitor the efficiency and productivity of the team working on the contract. By analyzing both work sheets and time sheets, the contracts manager can ensure that the project is on track and identify any potential issues or delays.

Explanation
Environmental control circuits are circuits used to measure and control temperature, air flow, and humidity in a building. These circuits are responsible for maintaining a comfortable and safe environment by adjusting the heating, cooling, and ventilation systems. They play a crucial role in ensuring optimal conditions for occupants and can also contribute to energy efficiency by regulating the usage of HVAC systems.

Explanation
http://en.wikipedia.org/wiki/Electrical_wiring_in_the_United_Kingdom

Explanation
Mineral insulated MICC cable to BSEN60702. Fire resistant cable to BS6387
Conductor: Plain annealed solid copper
Insulation: Compressed magnesium oxide (Inorganic)
Core identification: There is no identifing marks on the conductors.
Armour/Protection: Plain anealed copper tube sheath (Inorganic)
Sheat/Jacket: LSZH (Low smoke zero halogen)
Colour: Red
Voltage: 300/500v for light duty use
Operating Temperature: Maximum 250°C (But will operate up to a temperature of 1083°C but this will reduce the life of the cable), minimum bending 0°C
Applications: Suitable for fire protection applications such as alarm circuits, fire pumps and sprinklers, smoke control systems and emergency power & emergency lighting. Also used in process industries where flamable liquids or gases are present
Standards: BS60702 Part 1: Mineral insulated cables and their terminations with a rated voltage not exceeding 750V
BS6387, IEC60331, Categories C, W & Z,

Explanation
Cable Types:

Twin & Earth or Three Core & Earth
House wiring cable
Conductor temperature 70°C
S.W.A XLPE ( TLC - Standard SWA )
SWA with XLPE thermosetting insulation giving an increased current carrying capacity.
Conductor temperature 90°C
S.W.A PVC
S.W.A with standard PVC insulation.
Conductor temperature 70°C
Hituf
PVC insulated with Tough PVC thermosetting insulation giving an increased current carrying capacity.
Suitable for building sites and some garden and other tough conditions.
Conductor temperature 70°C
Applications

Method 100 - Above a plasterboard ceiling with less than 100mm insulation
Installation methods for flat twin and earth cable clipped direct to a wooden joist above a plasterboard ceiling with a minimum U value of 0.1W/m K and with thermal insulation not exceeding 100 mm in thickness
Method 101 - Above a plasterboard ceiling with more than 100mm insulation
Installation methods for flat twin and earth cable clipped direct to a wooden joist above a plasterboard ceiling with a minimum U value of 0.1 W/m K and with thermal insulation exceeding 100 mm in thickness
Method 102 - In an insulated stud wall with the cable touching the plasterboard
Installation methods for flat twin and earth cable in a stud wall with thermal insulation with a minimum U value of 0.1 W/m K with the cable touching the inner wall surface
Method 103 - In an insulated stud wall with the cable NOT touching the plasterboard
Installation methods for flat twin and earth cable in a stud wall with thermal insulation with a minimum U value of 0.1 W/m K with the cable not touching the inner wall surface
In conduit in an insulated wall (including Thermalite)
Clipped direct to a wall
Wherever practical, a cable is to be fixed in a position such that it will not be covered with thermal insulation
Notes:

When cables are grouped or bunched, any cables carrying less than 30% of the load may be ignored for the purpose of obtaining the rating for the rest of the group.
Where accurate calculations are required please refer to the IEE 17th Edition regulations.
Examples

An immersion heater rated at 240 V, 3 kW is to be installed using twin and earth cable. The circuit will be fed from a 16A MCB over 14m in a roof space which is insulated with glass fibre.The roof space temperature is expected to rise to 50°C in summer.

A. Where it leaves the consumer unit and passes through a 50 mm insulation-filled cavity,the cable will be bunched with seven others.
Required Cable Size: 10mm
This adds considerably to the costs and would make it difficult to terminate such a large cable in the accessories. A more sensible option would be to look for a method of reducing the required cable size.

B. Eight cables leave the consumer unit in two bunches of four
Result: 6mm

D. To attempt to make the cable size smaller, if the eight cables left the consumer unit in four bunches of two
Result: 4mm

C. If it were possible to run the cable out on its own then no grouping factor would apply.
Result: 2.5mm

E. Finally, if the cable left the consumer unit on its own and the cable was not in contact with the glass fibre and clipped direct to the rafters in the loft space.
Result: 1.5mm http://www.tlc-direct.co.uk/Technical/Charts/VoltageDrop.html

Explanation
*Max Cable Load referes to the maximum allowable current for the cable used in the configuration given above and will vary considerably under different configurations.

Caution - for Guidance ONLY
NO guarantee as to the accuracy of these values is given.
And they should be checked against some other source.

Cable Types:

Twin & Earth or Three Core & Earth
House wiring cable
Conductor temperature 70°C
S.W.A XLPE ( TLC - Standard SWA )
SWA with XLPE thermosetting insulation giving an increased current carrying capacity.
Conductor temperature 90°C
S.W.A PVC
S.W.A with standard PVC insulation.
Conductor temperature 70°C
Hituf
PVC insulated with Tough PVC thermosetting insulation giving an increased current carrying capacity.
Suitable for building sites and some garden and other tough conditions.
Conductor temperature 70°C
Applications

Method 100 - Above a plasterboard ceiling with less than 100mm insulation
Installation methods for flat twin and earth cable clipped direct to a wooden joist above a plasterboard ceiling with a minimum U value of 0.1W/m K and with thermal insulation not exceeding 100 mm in thickness
Method 101 - Above a plasterboard ceiling with more than 100mm insulation
Installation methods for flat twin and earth cable clipped direct to a wooden joist above a plasterboard ceiling with a minimum U value of 0.1 W/m K and with thermal insulation exceeding 100 mm in thickness
Method 102 - In an insulated stud wall with the cable touching the plasterboard
Installation methods for flat twin and earth cable in a stud wall with thermal insulation with a minimum U value of 0.1 W/m K with the cable touching the inner wall surface
Method 103 - In an insulated stud wall with the cable NOT touching the plasterboard
Installation methods for flat twin and earth cable in a stud wall with thermal insulation with a minimum U value of 0.1 W/m K with the cable not touching the inner wall surface
In conduit in an insulated wall (including Thermalite)
Clipped direct to a wall
Wherever practical, a cable is to be fixed in a position such that it will not be covered with thermal insulation
Notes:

When cables are grouped or bunched, any cables carrying less than 30% of the load may be ignored for the purpose of obtaining the rating for the rest of the group.
Where accurate calculations are required please refer to the IEE 17th Edition regulations.
Examples

An immersion heater rated at 240 V, 3 kW is to be installed using twin and earth cable. The circuit will be fed from a 16A MCB over 14m in a roof space which is insulated with glass fibre.The roof space temperature is expected to rise to 50°C in summer.

A. Where it leaves the consumer unit and passes through a 50 mm insulation-filled cavity,the cable will be bunched with seven others.
Required Cable Size: 10mm
This adds considerably to the costs and would make it difficult to terminate such a large cable in the accessories. A more sensible option would be to look for a method of reducing the required cable size.

B. Eight cables leave the consumer unit in two bunches of four
Result: 6mm

D. To attempt to make the cable size smaller, if the eight cables left the consumer unit in four bunches of two
Result: 4mm

C. If it were possible to run the cable out on its own then no grouping factor would apply.
Result: 2.5mm

E. Finally, if the cable left the consumer unit on its own and the cable was not in contact with the glass fibre and clipped direct to the rafters in the loft space.
Result: 1.5mm

Explanation
Copper cored data communication cables are twisted along their length in order to reduce electrical interference. Twisting the pairs of conductors helps to cancel out electromagnetic interference from external sources, such as nearby cables or electrical equipment. This interference can degrade the quality of the signal being transmitted through the cable, so reducing it is crucial for maintaining reliable data communication.

Explanation
A switch is designed to disconnect a supply under full load conditions. It is a device that can open or close an electrical circuit, allowing or interrupting the flow of electricity. Unlike a fuse, which is a protective device that melts and breaks the circuit when there is an overload or short circuit, a switch can be manually operated to disconnect the supply even when the load is at its maximum. An isolator is also a device used to disconnect a supply, but it is typically used for maintenance purposes and not intended for operation under full load conditions. A detector is a device used to sense or detect certain conditions and does not have the function of disconnecting a supply.

Explanation
In situations where there is a risk of an explosion due to the presence of fumes and gases, electrical switches and control equipment need to be mounted in flame proof enclosures. This is because flame proof enclosures are designed to contain any potential explosion within the enclosure, preventing it from spreading to the surrounding environment. By mounting the switches and control equipment in flame proof enclosures, the risk of ignition and explosion is minimized, ensuring the safety of the surrounding area.

Explanation
Why do we need residual current devices?

{5.3} has stressed that the standard method of protection is to make sure that an earth fault results in a fault current high enough to operate the protective device quickly so that fatal shock is prevented. However, there are cases where the impedance of the earth-fault loop, or the impedance of the fault itself, are too high to enable enough fault current to flow. In such a case, either:

1. - current will continue to flow to earth, perhaps generating enough heat to start a fire, or

2. - metalwork which is open to touch may be at a high potential relative to earth, resulting in severe shock danger.

Either or both of these possibilities can be removed by the installation of a residual current device (RCD). http://www.tlc-direct.co.uk/Book/5.9.1.htm

In recent years there has been an enormous increase in the use of initials for residual current devices of all kinds

Explanation
TT systems

This arrangement covers installations not provided with an earth terminal by the Electricity Supply Company. Thus it is the method employed by most (usually rural) installations fed by an overhead supply. Neutral and earth (protective) conductors must be kept quite separate throughout the installation, with the final earth terminal connected to an earth electrode (see {5.5}) by means of an earthing conductor.
Effective earth connection is sometimes difficult. Because of this, socket outlet circuits must be protected by a residual current device (RCD) with an operating current of 30 mA {5.9}. {Fig 5.4} shows the arrangement of a TT earthing system. http://www.tlc-direct.co.uk/Book/5.2.2.htm

Explanation
TN-C system
this installation is unusual, because combined neutral and earth wiring is used in both the supply and within the installation itself. Where used, the installation will usually be the earthed concentric system, which can only be installed under the special conditions listed in {5.7}. http://www.tlc-direct.co.uk/Book/5.2.5.htm

Explanation
Isolators used to isolate electrical supplies are designed to operate under no-load conditions. This means that they are intended to be used when there is no current flowing through the circuit. Isolators are used to disconnect electrical equipment from the power source for maintenance or repair purposes, and it is important to ensure that there is no current flowing through the circuit to prevent any accidents or damage to the equipment or personnel. Therefore, isolators are specifically designed to handle no-load conditions safely and effectively.

Explanation
Before starting work on a site, a contracting electrician should identify hazards and the personal protective equipment required. This is important for the safety of the electrician and others working on the site. By identifying hazards, the electrician can take necessary precautions to prevent accidents or injuries. Additionally, knowing the personal protective equipment required enables the electrician to wear the appropriate gear to protect themselves from potential hazards. This ensures a safe working environment and minimizes the risk of accidents.

Explanation
http://www.tlc-direct.co.uk/Book/8.1.1.htm
The person who carries out the test and inspection must be competent to do so, and must be able to ensure his own safety, as well as that of others in the vicinity. It follows that he must be skilled and have experience of the type of installation to be inspected and tested so that there will be no accidents during the process to people, to livestock, or to property. The Regulations do not define the term 'competent', but it should be taken to mean a qualified electrician or electrical engineer.

Explanation
Inspection bends, elbows, and sleeves are used on long conduit runs to reduce stress on cables when drawing them in. These components help to create smoother bends and turns in the conduit, which minimizes the strain and tension on the cables during the installation process. By reducing stress, the risk of damaging or breaking the cables is decreased, ensuring a successful and safe installation.

Explanation
When using metal trunking as a circuit protective conductor, continuity is maintained at all joints by fitting copper continuity straps. Copper continuity straps are used to ensure a continuous electrical connection between different sections of the trunking. They are typically installed at each joint to provide a low-resistance path for the flow of electricity, preventing any interruption or break in the circuit. This helps to maintain the overall integrity and effectiveness of the circuit protective conductor system.

Explanation
Spring toggles and screws are commonly used when fixing electrical equipment to hollow walls. Hollow walls are typically made of drywall or plasterboard, which are not strong enough to support heavy objects on their own. Spring toggles provide additional support by expanding behind the wall surface, creating a secure anchor point. The screws are then used to attach the electrical equipment to the spring toggles, ensuring a sturdy and reliable installation.

Explanation
Armoured cables are designed to provide protection to the internal conductors from external factors such as physical damage and moisture. These cables are often heavy and rigid, which can create stress on the cables if they are not properly supported. By supporting the cables at regular intervals, the stress on the cables is reduced, preventing potential damage and ensuring their long-term performance and reliability.

Explanation
After cutting and threading conduit, burrs should be removed using a reamer. A reamer is a tool specifically designed to remove burrs and smooth the edges of a hole or conduit. It helps ensure that the conduit is clean and free from any sharp edges that could potentially cause injury or damage to wires or cables that pass through it. Using a reamer is the most effective and appropriate tool for this task.

Explanation
Portable power tools should be inspected before and after use to ensure their proper functioning and safety. Inspecting the tools before use allows for identifying any potential issues or damages that may affect their performance or pose a risk to the user. This helps prevent accidents and ensures that the tools are in good working condition. Similarly, inspecting the tools after use allows for detecting any wear and tear, damage, or loose parts that may have occurred during the operation. This allows for timely repairs or replacements, ensuring the longevity and reliability of the tools.

Explanation
When there are holes in floors and ceilings, restoring them with suitable materials and to the original thickness can help prevent the spread of fire. By filling the holes, it creates a barrier that can restrict the movement of fire, smoke, and heat through the building. This can help contain the fire to a specific area and prevent it from spreading to other parts of the building, potentially saving lives and minimizing damage.

Explanation
When terminating optical cables, it is important to handle the dangerous waste materials properly. Ignoring and leaving them in situ can lead to environmental contamination and potential harm to individuals. Leaving them on site with instructions for disposal may not ensure proper handling and disposal. Throwing them outside buildings is irresponsible and can pose risks to public health and safety. Therefore, the correct answer is to take the waste materials off site and place them in suitable containers to ensure proper containment and disposal.