Elect Installation & Maintenance Work 2, WASSCE (SC), 2019

Question 2


  1. State three precautions that should be taken to prevent accidents in an electrical workshop.

  2. A fuse is an essential part of an electric circuit. Explain:

    1. its purpose.

    2. how it operates

    3. why the fuse element must be of correct rating.

    4. draw a labelled diagram of a rewireable fuse with the holder.

    1. List three parts of a photometer.

    2. State the functions of each of the parts listed in 2(c)(i).

    1. State:

    2. two conditions that should be satisfied for the registration of a small scale electrical installation business.

    3. four factors to be considered in starting a small-scale electrical installation business.

Observation

In part (a), performance was above average.


In part (b), Performance was above average.


In part (c), Performance was above average.


In part (d), Performance was fair. Many candidates failed to state the requirements for setting small business.


The expected answers include:


  1. Precautions to be Taken to Prevent Accidents in Electrical Workshop


    • Never assume any conductor to be dead.

    • Test equipment/appliances before powering them.

    • Wear protective clothes/shoes/boots/gloves/goggles.

    • Avoid littering the workshop with oil.

    • Avoid walking on wet floors.

    • Avoid obstructions.

    • Avoid horseplay.

    • Avoid use of faulty tools.

    1. Purpose of Fuse

    2. Is to protect the circuit/equipment/appliances against short circuit/overload/excess current.


    3. Fuse Operation

    4. It operates by melting/cutting of the element when there is excess current supply/short circuit


    5. Reason for Correct Rating of Fuse

    6. It is important to operate under correct rating to prevent fire outbreak/damage of equipment/appliances/circuits.


      OR

      It is only at the correct rating that the protective function is guaranteed.


    7. A Labelled Diagram of a Rewireable Fuse with the Holder.


    8. Fuse/Carrier/Bridge.


      Holder/Base.


      Any correct labelling.


      NOTE: 1 mark from fuse/carrier/bridge.


      1 mark from holder/base.


      • Parts of a Photometer.
      • Connecting ring

      • Transparent film

      • Selenium

      • Steel plate

    1. Functions of Photometer Parts.
    2. Connecting ring – this allows connection to the instrument (both positive and negative terminals).


      Transparent film – it allows light rays to penetrate into selenium.


      Selenium – this allows release of electrons to enable the flow of current.


      Steel base plate – this act as base or holder for the cell.


    1. Conditions for Registration of a Small Electrical Installation Busines

      • Certificate of competence/licence

      • Location/address

      • Referee

      • Tax clearance

      • Business name

    2. Factors to be Considered in Starting a Small Scale Electrical Installation Business

      • Capital/fund

      • Land/shop/location

      • Labour/personnel

      • Tools/material/equipment

      • Client/market

      • Business idea/skill