Drawings Flashcards
Projection
A representation of an object on a 2D plane
Orthagonal Projection
Shows the ‘faces’ of an object: front, back, left, right, top, bottom.
Isometric Projection
Represents the object three dimensionally from a given corner.
First Angle
A projection of an object onto a plane that sits behind the object
Third Angle
A projection of an object onto a plane between the object and the viewer
Leader Line
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Outline
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Hidden Outline
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Extension Line
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Dimension Line
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Centre Line
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Perspective Drawing
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Oblique Drawing
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Length
The longer side of an object
Width/Depth
The shorter side of an object
Thickness/Height
The measurement not covered by width
Drawing Scale is expressed as a ratio; e.g. 1:1 = actual size.
2:1 = Double Size; 1:20 = One 20th; 1:50; One 50th, etc.
Site drawings are often made at a scale of 1:200, even 1:500. Mechanical drawings are often made at 1:1 or 2:1.
Block Diagram
A type of flowchart designed to illustrate the layout of an electrical system.
In large installations, a number of Block Diagrams might be used.
Circuit Diagram
Often, a circuit diagram will not align perfectly with the circuit itself.
Australia/NZ align with International Standards, but it is still common to see regional differences between other countries.
Wiring Diagram
More realistic than a circuit diagram; a wiring diagram shows the terminals and connections of components.
A wiring diagram is used:
- When the installation is wired in the first place
- When a component in the circuit is replaced
- As an aid for fault finding.
Ladder Diagram
A form of circuit diagram. The Active and Neutral are drawn as columns on either side, forming the ‘rails’, while the wiring across represents the ‘rungs’
Cable Schedule
Not commonly used for domestic situations; a cable schedule is a table presenting information about cable used in an installation.
Information such as:
- Cable length
- Type and size
- Colour
- Termination detail
- To and from devices
- Route
- Conduit detail
Title Block
An essential component of every mechanical drawing. The title block contains the following information:
– Company or organization name – Title of drawing – Size of the paper used – Drawing number – Date the drawing was done – Sheet number and number of sheets (pages) – Projection system used.
Schematic Drawing
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Location Drawing
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Location Plan
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Site Plan
A site plan is a large scale drawing that shows the full extent of the site for an existing or proposed development. Site plans, along with location plans, may be necessary for planning applications.
Single-Line Diagram
A single line diagram, also referred to as a one-line diagram, is usually a single page document that represents a facilities electrical distribution infrastructure. It will have one single line shown for bus (or cable) to represent all three phases.
