COMMON ELECTRICAL SYMBOLS
Electrical Symbols are small drawings or pictograms used to represent various electrical
devices in a diagram or plan of an electrical circuit. These symbols are used in sketching
schematic diagrams and electrical plans for numerous types of electrical works. Practically
any electrical fixture found in a house has a symbol that coincides to said fixture on an
electrical wiring diagram. These are very useful guide for an electrician or electrical
contractor, thus, making the wiring easier to install as well.
The following are common electrical symbols used in sketching wiring plan and
diagram.
Symbol Description Symbol Description
Conductor/Wire Ammeter
Terminal Voltmeter
Switch Galvanometer
Fuse Wattmeter
Connected Wires Wires Not Connected
Circuit Breaker Push Button
Cell Bell
Battery Buzzer
Resistor Speaker
Capacitor Antenna
Diode Male plug
Service Entrance (3
Ground
wires)
Duplex Convenience
Lightning Arrester
Outlet
Kilowatt-Hour Meter Range Outlet
Power Panel Board Special Purpose Outlet
1
Lighting Panel Board Weatherproof Outlet
Incandescent Lamp Floor Outlet
Fluorescent Lamp S1 Single Pole Switch
ELECTRICAL SIGNS
Your power tool with its manual may contain "WARNING ICONS" (a picture symbol
intended to alert you to, and/or to instruct you how to avoid a potentially hazardous
condition). Knowing and understanding these symbols will help you operate your tools better
and more safely.
Electrical signs and stickers alert students, workers, and visitors to electrical hazards
in the area. Alerting workers to high voltage areas, electrical hazards, power lines and other
electrical equipment in the area, can help prevent fires and injuries. Proper electrical signs
can inform workers of the dangers in the area.
Electrical Symbols Meaning
CAUTION indicates some measures
m
precautionary potential hazardous against
situation which, if not result to a minor avoided, may
or moderate injury.
SAFETY ALERT indicates that a
person should observe extra
awareness
PROHIBITION means that any activity
Is not allowed
as stated by the symbol.
DANGER specifies hazardous situationwhich, if not
avoided, will result to a serious injury or even death.
WARNING specifies a potentially hazardous
situation which, if not avoided, could result to
serious injury or even death.
READ AND UNDERSTAND
INSTRUCTION MANUAL means that a person
should make some reading before doing any activity.
WEAR EYE PROTECTION indicates that a person
should wear safety goggles or any related protection
for the eyes.
2
ELECTRICAL HAZARD indicates that electrical
hazard is present in the area.
VOLTAGE DANGER indicates high voltage in the
area and surrounding equipment.
ELECTRICAL WIRING DIAGRAM
The flow of current in a conductor or wire can be represented by diagram. There are
two types of diagram: pictorial diagram and schematic diagram.
A. Pictorial diagram is a sketch of electrical circuit that shows the external appearance of
each component. It is much like a photograph of the circuit and uses simple images of
parts.
Sample pictorial diagram of one bulb controlled by a single pole switch
using 9-volt battery source.
b. Schematic diagram is a sketch showing the components of the circuit using standard
electrical symbols. It shows the actual number of components and how the wiring is
routed but not the actual location.
Diagram A Diagram B
Sample schematic diagrams of one bulb controlled by single pole switch using direct current
(Diagram A) and alternating current (Diagram B) source.
Notice the difference in the diagram of the sources of current: direct current and
alternating current. You will be making your own diagram later on.
Types of Circuit:
1. Series Circuit is a circuit in which lamps are arranged in a chain, so that the current
has only one path to take. The current is the same through each load. Example of this is
the Christmas lights. It consists of a number of bulbs that are connected side by side to
meet the voltage requirement which is 220 volts for alternating current.
3
Schematic diagram of three bulbs connected
Pictorial diagram of Christmas light in in series controlled by a single pole
series circuit switch
2. Parallel Circuit is a circuit in which lamps are connected across the wires. The voltage
across each load on parallel circuit is the same. The advantage of using parallel circuit
is that even if one of the lamps fails, still the remaining lamps will function.
Pictorial diagram of two bulbs connected in Schematic diagram of three bulbs connected
parallel circuit controlled by a single pole in parallel circuit controlled by a single pole
switch. switch
Did you notice the difference of the diagrams of the series and the parallel circuit? I
hope you did, because again, you’ll be drawing your own diagram later on.
ELECTRICAL PLAN
Electrical plan is a graphical presentation of electrical wiring connections to install in
a particular house or building. It indicates the position of electrical fixtures such as
convenience outlets, switches, lightings, door bells, and others to be installed.
Sample electrical plan of a single-family dwelling
But how would I know how many electrical fixtures are there in the plan? You’d have to
look at the symbols used in the plan then count them. Go back to pages where the electrical
symbols are found. The symbols are all there.
