What Is A Circle With An X In A Circuit Diagram?

Do you ever get confused by the symbols used on wiring diagrams? Why can’t they just write down what each symbol means for ease?

Electrical diagrams use many symbols as the drawings and diagrams are expected to be used by qualified people. You can read the drawing at a glance. To write down every symbol for the layman in a circuit drawing would be time-consuming and cost money to do so.


What is a circle with an x in a circuit diagram?

Bulb or lamp. If you see a circle with an x, it represents a bulb or lamp in the circuit. Most first fix wiring diagrams will indicate where every light fitting is located.

Drawings and symbols are a vital piece of the electrician’s daily working environment so they can deliver the precise job for the customer.

What is the symbol of the incandescent bulb?

X in a circle. However, the incandescent light bulb can vary from a simple X in a circle to something more akin to a coiled wire inside a circle.

These symbols will be phased out as incandescent light bulbs are phased out completely.

Do all light bulbs use the same symbol?

No, there are various symbols for different light bulbs and where the light bulb is located. 

Here is a list of commonly used light bulb symbols on wiring diagrams:

Why is it important to represent components with symbols?

Ease and speed. Electrical drawings or diagrams are produced for the qualified electrician/ electronics engineers and, as such, are full of symbols pertaining to what’s required within the circuit.

Without symbols, the electrical diagrams could become cluttered and confusing to read. Symbols simplify the process for the architect and the electrician.

What does a circle with a line through it mean in electrical?

Power off or sleep mode. IEC 60417-5008, the power-off symbol (circle) on a button or toggle indicates that using the control will disconnect power to the device.

(0 or ◯ means off.) IEC 60417-5009, the standby symbol (line partially within a broken circle), indicates a sleep mode or low power state.

Which is off I or O?

I=on O=off. The symbol represents both and on the position in the circuit. This symbol is normally found on push on or off switches known as IO buttons.

IO switches can toggle on and off by depressing the button.

What are the symbols for power used on a wiring diagram?

You probably guessed the electrical /electronics industry uses a lot of symbols to denote what is needed in wiring diagrams.

If you thought light bulb symbols can be confusing here are some other symbols that are regularly used with their meanings:

VoltageVoltV or EUnit of Electrical PotentialV = I × R
CurrentAmpereI or iUnit of Electrical CurrentI = V ÷ R
ResistanceOhmR or ΩUnit of DC ResistanceR = V ÷ I
ConductanceSiemenG or ℧Reciprocal of ResistanceG = 1 ÷ R
CapacitanceFaradCUnit of CapacitanceC = Q ÷ V
ChargeCoulombQUnit of Electrical ChargeQ = C × V
InductanceHenryL or HUnit of InductanceVL = -L(di/dt)
PowerWattsWUnit of PowerP = V × I or I2 × R
ImpedanceOhmZUnit of AC ResistanceZ2 = R2 + X2
FrequencyHertzHzUnit of Frequencyƒ = 1 ÷ T

What is a conductor symbol?

Conductors are symbolised as a straight line on a wiring diagram.

What are the 6 most common symbols used for an electrical schematic diagram?

These are used more in electronics rather than an electrician’s circuit diagram, which is far less complicated in many ways.

Below is an overview of the most used symbols in circuit diagrams:

  • The symbol for the battery is indicated by the 9V+ 
  • The resistors shown on the diagram are denoted as R!. R2, and R3 with a zigzag line
  • Potentiometer, also symbolised by a zigzag line in this drawing
  • Schematic symbol of a transistor
  • Integrated circuit
  • Logic gates
  • Inductor and transformer.

What does the circle mean in a circuit?

It can vary. A plain circle on a wiring diagram can indicate either the output is active or there is a logic gate that is inverting.

What is the arrow symbol in a circuit?

Current flow. The arrows can indicate the direction the current is flowing in the circuit. If there are no values stated against the circuit, you must assume that the circuit is continually live until otherwise proven different.

What are the three most common symbols found on a blueprint?

There will always be a directional arrow or compass to inform the person reading the drawing as to the property’s orientation.

In addition, you will find these commonly used symbols on a blueprint:

  • Staircases will be defined by parallel lines with their measurements.
  • Doors are indicated and may show an arc as to the opening direction of the doors.
  • Windows.
  • Walls.
  • Position of the intended appliances.

Suppose you are working on a new build project. In that case, you may not be the only trade working on the drawings, so for electricians, it’s important to have a separate wiring diagram apart from the overall construction blueprint.

What are the symbols for switches in and around the home?

Many variations show multiple switching switches to fused switches. Below are three examples of switch symbols used in the UK:

Does the US use different symbols for wiring diagrams?

Yes. The USA uses its own NEC regulated wiring diagram guidelines, which differ from the UK.

However, an experienced electrician/ electronics engineer from either side of the pond would easily grasp the nuances used to depict various components in the circuit.

The circuits could not be interchangeable as the US operates a lower voltage power supply than the UK.

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