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Tuesday, December 22, 2015

Types of Electrical Drawings

Electrical drawings generally fall into four broad categories:
  1. Plans
  2. Schedules
  3. Diagrams
  4. Details and/or Elevations
We will examine each or these categories briefly and determine their place in the overall picture or project .

Electrical Plans and Plan Views

The electrical floor plan tells the electrician where each electrical device and piece of equipment is to be located related to the architectural features of the area. It shows the electrician where and how the conductors are to run. It helps locate the incoming service. Electrical plans are also used for estimating installation and material costs. By examining a plan, the electrician can take off, that is, count, the number of switches, outlets, fixtures, feet of wire, etc., that may be required for a particular job.

Types of Plans

1. Power plan

2. Lighting plan

3. Instrument plan

4. Underground plan

5. Equipment plan

6. Grounding plan

7. Conduit plan


Schedules are generally full sized drawings presenting a summary or collection of information. They are usually in tabular form. There should be some semblance of organization in a schedule, be it numerical, alphabetical or otherwise, so that the information is retrievable without scrutinizing every item in the schedule. The information should be complete with reference drawings, legends, or notes to make it self-explanatory.

Types of Schedules

1. Conduit and Cable Schedule

2. Junction box schedule

3. Transformer schedule

4. Fixture or device schedule

5. Lighting Panel (MCC) schedule

Electrical Diagrams

Diagrams show the electrical path, device wiring, sequence of operation, device relationship, or connections and hookups of the electrical installation. Occasionally the drawing types are combined or used as details for one or another type of drawing.

Types of Diagrams

1. One- line diagram

2. Schematic wiring diagram

3. Ladder diagram

4. Field wiring diagram

5. Panel wiring diagram

6. Instrument wiring diagram

7. Interconnection diagram

8. External connection diagram

9. Logic diagram

Detail Drawings

Detail drawings, or sheets, arc full-sized drawings showing complete information on a specific installation, conduit routing, equipment placement or connection, and so on. They may be elevation or plan views and are generally to a larger scale so that more detail can be called out. Several details, some times as many as nine, appear on one sheet.

Detail sheets are usually limited to one category of details per sheet, such as power details, lighting details, or grounding details

Review Questions

  1. List the four general categories of Electrical Drawings 
  2. List any four types of electrical plan 
  3. Write name of any four types of electrical diagrams 
  4. What are the different types of electrical schedules?
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