Question 5
- The diagram below shows the layout of a kitchen.
(i) Reproduce the diagram to specification.
(ii) Indicate the appropriate position of each of the following accessories on the diagram in 5(a):
I. cooker unit;
II. 2 way switch;
III. 13 A socket outlet;
IV. 15 A socket outlet
V. incandescent lamp;
VI. 4-way MCB consumer unit.
(iii) State the correct cable size for each of the accessories in 5(a)(i)
(b) Complete the table below.
(i) Faults associated with contactor.
Causes |
Faults |
I. Contactor not energising. |
|
II. Circuit not completed after contactor is energised |
|
III. Contactor vibrating. |
|
IV. Welded contacts of the contactor. |
|
(ii) State two factors that should be considered before using a cable.
Observation
In part (a), many candidates who attempted this part performed above average. Candidates were given full mark for having the knowledge that the one 2-way switch should be by the door, the incandescent lamp should be at the centre of the room and the cooker control unit should be close to the window.
In part (b), performance was poor as the question threw the candidates off balance. Many candidates performed poorly.
The expected answers include:
Specification
Layout
(ii) I - cooker unit - K
II - 2-way switch - N
III - 13 A Socket outlet - (L,P,O)
IV - 15 A Socket outlet - (L,P,O)
V - incandescent lamp -
VI - 4 way MCB Consumer unit - (4AO)
NB: There must not be duplication of letters
(iii) i. Cooker unit - 4 mm2
ii. 2-way switch - 1 mm2/1.5mm2
iii. 13A socket - 2.5 mm2
iv. 15A Socket outlet - 2.5 mm2
v. Incandescent lamp - 1 mm2/1.5mm2
vi. 4 – way MCB Consumer unit -
(bi) Faults Associated with Contactor
I - Open circuit/short circuit coil/no supply
II - Open circuit of the line conductors/high resistance on the contact
III - Dirty contact
IV - partial contact/loose contact/excess current
(ii) Two Factors that should be considered before Using a Cable
- Cable size
- Type of installation/building
- Type of insulation
- Environment
- Load
- Cost
- Durability/life span
(c) Four Factors Influencing Earthing System
- Ambient temperature
- Application/environment
- Load current/max rated current
- Suitable voltage drop
- Installation data
- Short circuit current
- Grouping
- Type of sheath Deposition