Lesson 7: Saftey in Household Circuits

New Information

Household Wiring

Inside your homes is many layers of wiring all occuring together, some in series, some in parallel and in both.

All of these wires will be running of the 240V supply going to your house, this voltages is enough to be lethal to a human through electrocution.

These are our electrical safety measures

Earth Wires

Inside every household power cable there is usually 3 metal prongs that attach to 3 different wires. 

The Active/Live Wire

• The active wire usually has a brown insulator coating

• Its role is to carry the electrical current back to the powerpoint from the device

The Neutral Wire

• The neutral wire is usually has a blue insulator coating

• Its role is carry the electrical current from the powerpoint to a the device 

The Earth Wire

• The earth wire is usually has a green/yellow insulator coating

• Its role is to carry the electrial current away from the circuit and into the ground

  • This will neutralise the current

  • It will only activate if an outside object becomes a part of the circuit

    • This incudes from damage of the device, cable or the powerpoint

Fuses

A fuse is a wire with high resistance and a low melting point.

If the fuse recievces too much current the wire will heat up and melt 

• The circuit will seperate and break the ciruit

If you short a circuit it will result in the high current often breaking a fuse.

In the image on the right, a fuse recieves too much current melts then breaks stopping the flow of the electricity.

Circuit Breakers

Newer houses use circuit breakers instead of fuses, they are easier to reset.

A circuit breaker a switch that can be turned off by high currents.

When a high current begins the springs in the circuit heat up casuing them to expand. This expansion disconnects the circuit.

After the switch is turned off it must be manually reset.

In the image to the left, a circuit breaker switch is turned into the on state allowing the flow of electrons. Shortly after the current increases causing the springs to heat up and expand. This activates the breaker putting it into the tripped position. This is then moved into the off position and reset.

Activities