Assessment 615: Electrical Systems Design Task A – Design project
Candidate name:
Date:
Time allowed
There are no time constraints to this assignment however, it is estimated that the work involved should take approximately 20 hours.
Task instructions
Candidates are required to successfully complete the following task consisting of 10 questions to achieve this assignment:
Candidates are permitted any relevant reference material such as IET On-site Guide, BS 7671 and internet access.
Read all information relating to the task carefully before attempting any questions. For this task you will require a copy of drawings 5357-A1 to A6. For the purpose of scaling, these should be provided in A3 format. You may, when marking up drawings, use A4 format if desired.
All questions must be completed for this project. You may use the space provided for your answers or you may produce them electronically on separate named sheets. Read each question carefully before attempting.
Drawings 5357-A1 to A6 show the proposed new hotel extension and new pool/café block. Information relating to building design and construction are detailed below. You may however make reasonable assumptions throughout your design giving reasons.
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The task has been successfully completed to the standards required
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Assessor/Tutor feedback to candidate on outcome of assessment (if applicable)
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Building Specification
Building Construction
Hotel Extension:
ξ The building is constructed on a concrete raft with 50 mm screed to the ground floor and chipboard on 100 mm wooded joists for the first floor.
ξ The walls are thermolite blocks with uPVC cladding, cavity and inner leaf blockwork with plaster finish. Inner wall partitions are blockwork with plaster finish.
ξ The roof is tiled on a wooden roof truss with waterproof membrane.
ξ Internal ceilings are plasterboard on the underside of wood joists.
Pool/Café block:
ξ The building is constructed on a re-enforced concrete base forming the swimming pool and floor with tiled finish throughout the basement areas.
ξ The first floor is pre-cast concrete on steel supports with 50 mm screed and non-slip vinyl finish. ξ The basement walls are re-enforced concrete with internal uPVC cladding.
ξ The basement ceiling utilises the underside of the concrete floor above.
ξ The café area walls are wood framed with uPVC outer cladding, thermal insulation and plasterboard inner lining.
ξ The tiled roof is supported on exposed decorative wooden trusses with internal plasterboard infills on the underside forming an open ’A’ roof space with the exception of the building section above the kitchen end of the building which has plasterboard ceilings 2.4 m above ffl forming an enclosed roof space above. ξ Inner walls are plasterboard partitions having aluminium frame.
Electrical Installation:
The existing hotel building forms part of a 400 V three-phase TN-C-S system. It has been assessed that there is sufficient capacity for the new works and a new CCU will be installed to supply the new distribution circuits. Ze and PFC have been measured and recorded as 0.09 Ω and 5 kA respectively.
It has been assessed that following installation of the new three-phase distribution circuit to the pool/café block, Zdb and PFC for the new distribution board within the block will be 0.11 Ω and 3.7 kA respectively.
Fire alarm system
This is to be installed by specialist contractors but a 13 A un-switched fused connection unit will be required in the pool/café block to supply a repeater panel.
Heating, ventilation and air-conditioning
This is to be installed by specialist contractors and any supply details are contained in the design specification. Any further considerations can be ignored.
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Design Specification Detail
Within the pool/café block, the following design criteria applies Ambient temperatures All basement pool areas 40 °C Café open area 25 °C
Café Kitchen/servery 35 °C
Wiring systems for lighting and small power (see additional
information below for specific circuits)
Grouping of circuits for lighting and small power (see additional
information below for specific circuits)
All basement pool areas PVC surface conduit with 90 °C thermosetting single-core non
sheathed cables
Café open area PVC surface conduit with 70 °C thermoplastic single-core non
sheathed cables
Café Kitchen/servery PVC surface conduit with 70 °C thermoplastic single-core non
sheathed cables
All basement pool areas Each circuit will be grouped with no more than 2 other circuits
Café open area Each circuit will be grouped with no more than 1 other circuit
Café Kitchen/servery Each circuit will be grouped with no more than 3 other circuit
Thermal Insulation All areas No thermal insulation affects the wiring systems
Circuit lengths All areas To be estimated from drawing scales. For the purpose of this
project, no circuit should exceed
approximately 30 m.
Other circuit specific detail
230 V 16 A dishwasher in kitchen Supplied by a three core 70 °C thermoplastic SWA cable clipped
direct
Servery food holding equipment. This unit requires a 16 A 400 V three-phase and neutral supply.
All pool equipment and sauna equipment. This equipment requires a 32 A 400 V three-phase and neutral supply. All equipment associated will be installed by a specialist from a local supply point in the
Supplied using five core 90 °C thermosetting SWA cable clipped direct
Supplied using five core 90 °C thermosetting SWA cable clipped direct
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equipment room provided as part of the contract.
The four fridges within the kitchen area should be supplied by two 16 A single phase circuits to specifically labelled socket-outlets for each fridge. Additional protection should be omitted for these circuits.
New summer house by existing pool. A 32 A distribution circuit from the pool/café block will supply this new structure which will have a four-way SP-N distribution board fitted.
Supplied by single-core 70 °C thermoplastic non-sheathed cable in surface PVC conduit
Supplied by a three core 70 °C thermoplastic SWA cable clipped direct
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Assessment 615: Electrical Systems Design
Task A – Design project
Candidate name:
Date:
Note: this question paper and associated drawings must be submitted for marking
1 As part of the electrical contract, the client is considering an electric vehicle charging unit in the car park supplied from the existing TN-C-S supply in the main hotel building. Following a site survey it has been decided to install the EV Charging Equipment as part of a TT earthing arrangement.
Draw a fully labelled circuit diagram illustrating the three-phase 400 V supply system and earthing arrangement from the sub-station transformer through to the charging unit. The diagram should show the total earth fault loop path for the charging unit.
Your diagram does not need to show the complete detail of distribution boards, metering or consumer control equipment although the diagram should, as a minimum, indicate a connection point for each item of equipment.
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2 a) Select, using manufacturers’ data, suitable luminaires for all parts of the pool/café block with exception of the sauna. Your selection should be based on
ξ energy efficiency
ξ environment/external influences
ξ aesthetics
ξ Your selection does not need to take into consideration suitable levels of illumination for the purpose of this project or any outdoor lighting.
b) Show, on either electronic or hard copies of the drawing, positions of socket-outlets and fused connection units for the new hotel block giving consideration to the following items of equipment in each room:
ξ kettle
ξ TV
ξ provision for phone charging and/or laptop use
ξ supply to a 700 W air handling unit for heating/cooling (installed by specialist)
ξ electric towel rail.
c) Show, on either electronic or hard copies of the drawing, positions of the luminaires selected giving each type a suitable form of identification on a separate key.
d) Show, on either electronic or hard copies of the drawing, how each circuit in the new hotel extension is to be arranged. The arrangement must take into account that a fault in any one room must not affect another room.
e) Show, on either electronic or hard copies of the drawing, any further distribution boards that may be required in the hotel extension.
f) Show, on either electronic or hard copies of the drawing, how each lighting circuit in the new pool/café block is to be arranged including switching.
g) Give each circuit a unique form of identification.
h) Complete the legend on the drawings using recognised symbols and descriptions for each symbol used on the drawings.
3 Select, with the aid of manufacturers’ data, a suitable range of circuit protective devices for this contract. Your selection should be based on the following:
ξ Prospective short circuit currents
ξ Requirements for additional protection and special locations.
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4 This question may be answered using the Table 1 or Table 2. It is strongly recommended that you use pencil when completing the table to allow for recalculation of figures.
Determine, for every final circuit in the café/pool block, each of the following.
a) Design current (Ib)
b) Nominal rating and type of protective device (In)
c) Method of installation reference
d) Rating factors that apply
e) Minimum cross-sectional area of live conductors for current capacity and voltage drop f) Actual voltage drop.
g) Maximum permissible disconnection time for each circuit as given in BS 7671.
h) Earth fault loop impedance
i) Maximum earth fault loop impedance as stated in BS 7671.
5 Determine, for one of the circuits supplying the fridges, the minimum possible cross sectional area of cpc which will satisfy the requirements disconnection as ADS under earth fault conditions and the adiabatic equation as Regulation 543.1.3 in BS 7671.
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6 For this question, use the table below. More copies may be made as necessary.
a) Determine the maximum demand for the pool/café block electrical installation before the application of diversity.
b) Determine the maximum demand for the pool/café block electrical installation following the application of diversity.
Circuit
Demand
Diversity factor
Demand following
diversity
Total
Total
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7 Explain, with the aid of a diagram, how electric shock protection is provided by one of the shaver points in the hotel extension bathrooms using the Protective Measure: Electrical Separation.
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8 List, using the box below, five typical extraneous conductive parts and five typical exposed conductive parts that may be found within this entire complex.
Typical Extraneous Conductive Parts
Typical Exposed Conductive Parts
9 Complete the box below relating to earthing and bonding.
Type of protective (earthing/bonding) conductor
Example of where this may be found within this complex
Minimum
permissible csa as BS 7671 (where
applicable)
Main Protective Bonding
Where PME
conditions apply
For non-PME
applications
Supplementary
equipotential
bonding
Without mechanical protection
With mechanical
protection
Functional earth
Earthing
Conductor
For TT installations For TN installations
cpc
Without mechanical protection
With mechanical
protection
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10 Complete the box below relating to isolation and switching.
Type of isolation or switching
Example of where this may be found within this complex
Further requirements
Isolation for
electrical
maintenance
purposes
Relating to securing safe isolation
Switching for
mechanical
maintenance
Relating to devices which are not under effective control
Relating to switching capability
Functional
Switching
Relating to rating
where used for
discharge lighting
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Assessment 615: Electrical Systems Design Assignment feedback (if applicable)
Candidate’s name:
Assessor’s name:
Tasks 1st Submission
Outcome
Pass/Fail
Q1
Q2
Q3
Q4
Q5
Q6
Q7
Q8
Q9
Q10
Resubmission
Outcome
Pass/Fail
IQA Signature (if sampled)
Target date and action plan for resubmission (if applicable)
2365 Level 3 Electrical Installations Candidate Pack 67
Assessor/Tutor feedback to candidate on outcome of resubmission
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