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2365-03 305 Task B

305 Task B – Marking Grid

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2365-305. Task B.

You should have the following for this task access to research tools, including the internet drawings 2365-C-01/02/03 writing materials a scientific calculator (graphical and programmable calculators are not permitted).

Read the following specifications in conjunction with the drawings and then complete all questions in this task. This task may be completed using the resources available such as reference books or the internet. Drawings 2365-C-01/02/03 show a proposed new highways depot. You are involved in the design, installation and commissioning of the electrical installation. You may make reasonable assumptions in your project work consistent with economic considerations and conducive to the most practical design solutions. A list of these assumptions, with reasons, must appear in the folder or binder, with your project. Whilst the use of manufacturers’ catalogues and data is encouraged, your project work should not involve any design from external sources. To complete the task, a combination of drawings/overlays/copies may be used. Computer aided design packages may be used providing that you gather and input any data required yourself. This task is open book and you are allowed to bring in research notes. 2365-305 Assignment Guide August 2013 v2.1 11

1a Select, with the aid of manufacturer’s data, suitable wiring systems giving reasons for your choice.

1b Show, on drawings/copies/overlays the proposed route of all wiring systems.

2 Show, on drawings/copies/overlays the installation divided into final circuits giving each circuit a unique form of identification.

3 Determine the design current (Ib ) for each final circuit.

4 Select a suitable type of protective device for all final circuits, giving reasons for your choice. Consideration must be given to load current

start-up current breaking capacity.

5 Determine, for the whole installation the a) maximum demand before the application of diversity

b) maximum demand with the application of diversity using information contained in the IET on-site guide.

6 Determine, for one of the high bay lighting circuits within the workshop, the minimum cross-sectional area of live conductors for current carrying capacity and voltage drop.

7 A trunking run within the electrical switch-room area is to contain the following single-core thermosetting stranded cables. 35 x 1.5 mm2 25 x 2.5 mm2 12 x 4.0 mm2 10 x 10.0 mm2 5 x 16.0 mm2

Determine the minimum size of trunking to be used.

1)

a) For the offices I would use pvc dido trunking around the walls so that it is easy

to install new sockets and data sockets. In the workshop I would use steel conduit for the sockets as this will protect the cables from physical damage. For light circuits I shall run them in trunking or tray high up in the ceiling so they are out of reach.

b) All circuit routs are drawn on the 5 separate circuit drawings. Andrew_Flynn_First_Floor_Light_Circuits.pngAndrew_Flynn_First_Floor_Ring_Circuits.pngAndrew_Flynn_Ground_Floor_Isolator_Circuits.pngAndrew_Flynn_Ground_Floor_light_and_3&4KW_Machine_Circuits.pngAndrew_Flynn_Ground_Floor_Ring_Circuits.png

2) This is shown on all the circuit drawings mentioned in previous question.3) Design current and other design info shown on this separate table sheet

Andrew_Flynn_Circuit_ Info.xlsl4) Breaker type, breaking capacity and start up current are shown on this separate

table sheet Andrew_Flynn_Circuit_ Info.docxFor all the light circuits and office ring circuits I decided to us a B type breaker as there is no mass inrush of current as only PC’s and basic equipment will be used in the offices. In the workshop I’ve used C type breakers due to not knowing what may be put onto the circuit so using a type c means it won’t trip if a small inrush of current occurs when a machine is needing 5-10 seconds of the full load. For the isolators and 3 and 4KW machines I used a type D breaker as I assume they will have a larch inrush of current which may last more than 10 seconds.

5) After adding up the total In I got 436AAfter Diversity;(9)Sockets 32+(32*7)*0.5= 144A(1)Lights [(10*4)+16+6]*0.9= 55.8A(2)Isolators and Machines 50+(16+16+32+20+16)*0.75= 125ATotal with Diversity is 324.8A

6) DB3/11/3ØThis circuit has 12 light fittings giving a total design current of 14A with a breaker of 16A running a length of 38m.Using the volt drop formula I found that the 4mm² cable was the right one to use.VD=mV/A/m*Design Current*Length

1000VD=11*14*38

1000VD=5.852VA max volt drop of 6.9V is allowed for lighting meaning 4mm² cable will be fine to use.

7) Total Cable Factors=(336+347.5+217.2+363+251.5)Total Cable Factors=1515.2The trunking size has to be 100mmx38mm as it has a trunking factor of 1542