EGD ELECTRICAL ELECTRICAL SYMBOLS. Distribution board

EGDELECTRICAL

ELECTRICAL SYMBOLS

Distribution board

• This board houses all the trip switches for the various circuits as well as the earth leakage relay or unit.

• It can also house other units such as timers or even an electricity meter.

Earth

• Used together with Earth leakage unit.

• This unit detects a leakage of electricity down to earth.

One way switchsingle pole

One way switchDouble pole

One way switchThree poles

Two way switch

Regulating switche.g. dimmer

SWITCHES

This device comes in various shapes and is used to break the

flow of current in a circuit

Socket outlet

Switched socket outlet

Allows the user to plug in different electrical appliances.

Fluorescent lights

3 x 40W

Lights – Bulb type

Lights – wall mounted

• Light types include bulbs and tubes.

• Energy efficient lighting uses less electricity.

• BULB: A bulb lights up when current flows through it, and is not polarised.

Light Emitting Diode

Light Emitting Diode or LED

• It lights up when current flows through it,

• but is polarised, and will not work if connected incorrectly.

AMPERE AND VOLT METERS

A V

AMPERE (A) This unit is used to measure the amount of current flowing

in a circuit

• Every appliance connected to a circuit will draw a certain amount of current

when in operation.

VOLT (V) This unit is used to measure electrical pressure.

• The single phase voltage used in SA for domestic use is 220 Volts

CELLS AND BATTERIES

• A cell is a single unit.

• Two or more cells, connected together creates a battery.

Mains switch (Industrial)

• Mains switch controls the power supply to the distribution board.

• Mains switch controls the supply inside the distribution board, to all the different circuit breakers inside

the distribution board.

Fuse

This device is used to break the flow of electricity whenever a circuit is

overloaded.

• This device is used as part of protection for electrical devices.

• Must be replaced when blown.

Circuit breaker

• Performs the same function as a fuse.

• When the switch trip, it only needs to be reset and not replaced.

Single pole single throw

Single pole, double throw

• This device comes in various shapes and sizes

• This device is used to break the flow of current in an electrical

circuit.

Push to make switch

Push to break switch

• PUSH TO MAKE SWITCH,

• release to break switch.

• NO (normally open circuit)

• PUSH TO BREAK SWITCH,

• release to make switch.

• NC (normally close circuit)

Symbol for ON / OFF

Resistors

• A resistor limits the amount of current flow in a circuit.

• These values are indicated by a series of coloured bands on them

Power supply types

• AC is the abbreviation for alternating current.

• AC is the electricity supplied to our homes and industry

• DC is the abbreviation for direct current.

• DC is the type of electricity supplied by a cell or battery.

Buzzers and bells

• A buzzer or a bell converts electrical current into a sound

wave.

• Can be used as a warning indicator

Transformer

• A transformer consist of coils, using the magnetic field created by the flow of the electricity input on the

primary side.

• It is use to step up (rise) or step down (lower) the supply of electricity

on the secondary side.

• Can only be used with AC cycle.

Capacitor- Electrolytic or non electrolytic

• It is use to store electrical current

• and the capacitor will then supply the stored current when needed.

Motor

M

• A motor uses electromagnetism to produce movement when the motor

is connected to electricity.

• In DC motors, if the polarity is changed, the motor will rotate in the

opposite direction.

Geysers

G

• Provides hot water.

• Water is heated by means of a thermostat regulated element.

Aerials

• Different types of aerials can be used for sending and receiving of

radio waves and signals.

ELECTRICAL

CIRCUIT

(1)