Educational Information

How to Change a Bulb

There are many types of bulbs available, but they all have one of the two fitting attachments;

1. Bayonet fitting 
This is perhaps the most well known bulb fitting in the world. Invented towards the end of the nineteenth century and utilising a mechanism originally developed for bayonet rifles, the bayonet fitting consists of a spring and two contacts with bayonet mounts on either side. To fit, simply depress the lamp into its holder, twist under the lugs and the bayonet mounts are retained by the springs, thus ensuring optimum contact - the simple push and twist most of us are familiar with.

2. Screw fitting
Using the metal screw as one contact and a single base as the other, the lamp simply screws into the fitting. Contact is made when the lamp screw is almost home, thus making the screw part both the physical and electrical contact that makes the circuit.
Be sure you know which one to buy when you go shopping. For rooms where good strong light is needed (kitchens) fluorescent tube lighting is the best.

  • Switch off the mains switch on the distribution board or electricity dispenser.
  • Switch off the light at the light switch or wall socket.
  • Note: If a lamp's bulb is to be changed, switch off the lamp switch and remove the plug from the wall socket.
  • Remove the faulty bulb. If the bulb is a bayonet type, insert it carefully into the light socket, and twist it gently until the bayonet pins slot into place. If the bulb is a screw-in type, insert it carefully into the light socket and turn it clock-wise until it sits firmly in the light socket.
  • Switch on the mains switch on the distribution board or electricity dispenser and then switch the light on.
  • Discard the old light bulb safely.
Wiring a Plug
There are two kinds plugs used in our homes. Those which have 3 cores (3 wires inside the plastic/rubber cover) and those with only 2 core (2 wires). A 2 core plug should only be used when the appliance is double insulated and marked with a symbol In a 3 core wire the third wire is the one with the earth link which is very important. 

Each wire inside the main wire is the colour coded for a good reason. Each colour belongs to a certain position in the plug. The thicker the wire th​e more current the more current it can carry – remember when replacing or joining an electric cord to use one of the same thicknesses. Here is the chart to help you choose a wire suitable for the electrical consumption of your appliances.

  • ​Bare the ends of the three wires inside the electrical cord for about half a centimetre, by cutting away the plastic insulation.
  • Gently twist the strands of copper wire with your fingers until each strand is tight.
  • Fold over the twisted strands.
  • Remove the plug cover by either "snapping" or unscrewing it.
  • Unscrew the little screws on each of the plug's pins.
  • Insert the twisted copper wires into the holes in the pins.
  • The green and yellow wire must always be inserted into the top pin.
  • The blue wire is inserted into the left pin (the pin is marked with a blue spot or the letter N).
  • The brown wire is inserted into the right pin (the pin is marked with a brown spot or the letter L)
  • Tighten the little screw on each of the plug's pins.
  • Make sure the electrical cord is firmly gripped by the arrestor clips.
  • Replace the cover of the plug.​