Question 4
- Name the parts labelled V, W, X, Y and Z.
- What type of lamp does the diagram illustrate?
- State one function each of the parts labelled V and Z.
- Name the gas used in filling the lamp.
- State three possible faults that could make the lamp not to light when switched on.
- Using Figs. 1.1, 1.2 and 1.3, draw the wiring diagram showing each lamp controlled independently by it.
- State three precautions to be taken when carrying out the wiring on a wiring board.
- List five materials needed in carrying out the wiring on a wiring board.
- State the standard required cable size that can be used when carrying out the wiring on a wiring board.
The diagram above illustrates an electric lamp. Study it carefully and answer the following questions.
Figs. 1.1, 1.2 and 1.3 illustrate three lamps, three one-way switches and a joint box respectively. Study the symbols and answer the following questions.
Observation
Performance was below average. Many candidates failed to understand that wiring board is a miniature house, hence every precaution must be observed.
The expected answers include:
-
- Labelled Parts of an Electrical Lamp
- Type of Lamp illustrated in 4(a)(i)
- Functions of V and Z
- Name of the gas used in filling the Lamp
Inert gas/argon
. - Possible Faults that could make the Lamp not to Light When Switched on
- Open circuit.
- Broken filament/damage element.
- Poor contact on terminals/pins.
- Broken/cracked bulb/lamp.
- Short circuited terminals/pins.
- Gas may have been used up.
- Faulty lamp holder.
V - (Coiled-Coil) filament
W - Bulb
X - Gas-filled interior/inert gas
Y - Insulation/insulator/cap/base/holder
Z - Contacts
Incandescent lamp/filament lamp (bulb)
V - it converts electrical energy to light energy/it is the part that glows/produce light
Z - it connects/links the lamp to the source of supply/energy
-
- Wiring Diagram Showing Each Lamp Controlled Independently by Corresponding Switch
- Precautions for Wiring on a Wiring Board
- Ensure usage of correct tools
- Ensure tight connections (to avoid partial contact).
- Ensure that live that is coming from the supply is taken to the switches (and the neutral to the lamp).
- Ensure usage of correct cable size.
- Isolate the supply from the installation when wiring.
- Avoid short circuiting
- Avoid the use of uninsulated tools.
- Materials Needed for Wiring on a Board
- Cable (PVC).
- Clip/saddle.
- Brass nails.
- Screw.
- Insulation tape.
- Conduit pipe.
- Pattress.
- Cable Size 1.5 mm2