Elect Installation & Maintenance Work 2, WASSCE (SC), 2018

Question 4

The diagram below shows a circuit consisting of a lamp controlled by three in dependent switches.

(i) Using the diagram, complete the table below.

Switch position			Circuit condition	Lamp condition
SW1	SW2	SW3	Circuit condition	Lamp condition
Up	Up	Up
Up	Up	Down
Up	Down	Up
Up	Down	Down
Down	Up	Up
Down	Up	Down
Down	Down	Up

(ii) State one precaution to be taken while carrying out the installation in 4(a)(i).

(b) The diagram below illustrates a major equipment used in an electrical workshop. Study the diagram and answer the questions that follow.

(i) Identify the equipment.
(ii) Name the parts labelled I to V.
(iii) State one function of the part labelled III.

(iv) State three precautions to be taken while using the equipment during installation

Observation

In part (a), performance was below average as many candidates failed to get the last three operations right. Candidates response to this question shows that they were confuse.

In part (b), Most candidates labelled the part correctly. Few candidates failed the labelled part III which is trigger switch or power switch.

The expected answers include:

4 (ai)

Switch Position			Circuit condition	Lamp condition
SW1	SW2	SW3	Circuit condition	Lamp condition
Up	Up	Up	Close [1]	ON [1]
Up	Up	Down	Open [1]	OFF [1]
Up	Down	Up	Open [1]	OFF [1]
Up	Down	Down	Close [1]	ON [1]
Down	Up	Up	Open [1]	OFF [1]
Down	Up	Down	Close [1]	ON [1]
Down	Down	Up	Close [1]	ON [1]

(ii) One Precaution to be Taken While Carrying out Installation in 4 (a)(i)

Ensure that all connections are mechanically sound
Ensure that there is no exposed conducting parts
Ensure electrical continuity
Ensure usage of correct tools for the installation
Observe colour coding

(bi)      (Hand) drilling machine
(ii) i -     drill bit
ii    -     chuck
iii    -     trigger
iv   -    forward and reverse switch
v    -    grip/handle

(iii) One Function of the Part Labelled III
The part labelled III is used for switching ON and OFF the machine

(iv) One Precaution to be Taken While Carrying out Installation in 4 (a)(i)

Remove chuck keys from drills prior to use
Hold tools firmly and maintain good balance
Secure the work in a holding device not in your hands

Put on your safety wear while operating the equipment