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A complete guide to electrical drawings, blueprints & electrical wiring.


Electrical Drawings


Content


Reading Electrical Drawings


The electrical drawings consist of electrical outlets, fixtures, switches, lighting, fans, and appliances. The details of an electrical supply from the power source to each electrical equipment in the building are provided on electrical plans. Let’s see the details provided at different locations of drawings. Recall that the general notes are provided on the first page, along with legends and symbols. It consists of instructions followed during the complete installation of wiring, switches, lights, and appliances. It also provides details of the owner’s requirement or renovation guidelines.




Recall that every drawing has its symbols with descriptions that are provided in the legends. Electrical systems such as lights, switches, circuit breakers, distribution panels, and fixtures are denoted using various symbols described in legends. An electric planer is an instrument that helps to shave and shape wood.


Legends contain abbreviations with symbols used for appliances, switches, panels, and other fixtures shown in a plan view. Floor plans do not include notes or details for all those symbols used on the plan. The best practice is to refer to legends before moving on to the plans.



Electrical drawings contain many fixtures, switches, and panels; complete names or text for all these items will be mixed-up with the plan and difficult to read. The abbreviations table provides the details of text written beside several symbols used in the electrical drawings.


The abbreviations or short names used in the plan are defined on the first page of electrical drawings. The electrical plans are schematic, using symbols and abbreviations to denote the various appliances such as distribution panels, starters, sound system, television, and many more.


For example, the plan consists of a symbol with text TV or MCC; we need to check the abbreviation table to find the full form. When we checked according to the alphabetical order, we found that:

  • TV - Television, and

  • MCC - Motor Control Center.

So abbreviations used might differ from plan to plan.


Wall lines are often drawn lighter than the fixtures with dark lines to make the system particulars stand out clearly. In some instances, the fixtures might be shaded for easier identification. The continuous line represents the wiring required for equipment, while the bold type represents the fixture symbol.


For example, the plan consists of text R1, R2, R3, and so on, nearer the symbol with a continuous line from one another. The electrical fixture represents the light fixture, and the continuous line represents the wiring required from the respective switchboard. To find more fixture details, we need to refer to the schedules.


Recall that the schedules include manufacture, type, model, size, and details of the equipment. The electrical drawings include schedules for the light fixture, equipment, and load details, as shown in the image. Schedules help to know details of the equipment or item used on the electrical plans.


The electrical drawings include lighting fixtures and appliances that are provided in symbols on the plans. All the equipment needs to be described to estimate, order, and install at the site. The schedules fulfill these requirements.


For example, the plan consists of text R1, R2, R3, and so on nearer the symbol. The symbol and name represent different light types used. So to find the details, we first refer to the legends table and then check the schedule for light fixtures in the respective sheet.


Electrical plans are generally drawn at the same scale as the floor plans. The scale provided on the plan helps to measure the size, length, and distance of the equipment. The most common scale is 1⁄4" = 1'-0" (1:50 metric) for residential and small commercial projects, and 1⁄8" = 1'-0" (1:100 metric) for large commercial ones, where electric symbols work.


The scale at which the electrical plans are drawn is provided either adjacent to or directly below the drawing title. Sometimes designers might enlarge the detailed and related equipment drawings with their respective scales shown below the drawing.


The electrical drawings consist of electrical outlets, fixtures, switches, lighting, fans, and appliances. General notes, abbreviations, legends, and symbols, are found on the first page of the electrical drawings. Schedules help to find the details of the equipment or fixtures used on the plans.





 


Electrical Plans


In this module, we will learn about reading electrical plans and their usage. Skip to Quiz!


Electrical Plans


Engineers, architects, and electrical contractors are the primary designers of electrical plans. However, interior designers decide about wire routing and where fixtures like light bulbs or TV equipment are installed. It is also used to check how it will affect the interiors of a building.


A designer needs to coordinate the reflected ceiling plan to provide the correct location of light fixtures, registers, and appliances with the other construction trades. Electrical plans include multiple drawings describing the respective layout, such as power distribution layout, panel layout, wiring layout, and fixtures layout.




It represents an electrical blueprint and drawing symbol. The wiring layout consists of wiring routing is a set path for wires. These paths are inside the ceiling and can be seen in a wiring layout. As we can see in the image, the wiring provided to the light from the switchboard.


As seen in the picture, the conduit layout with junction box installed refers to the drawings available at the site. The ceiling is installed once all the wiring is done.


The details about fixtures, installation methods, or any information necessary to read the drawing are provided in a section of the drawing called plan notes. The location of fixtures is provided in electrical plans, and other details are provided in the plan notes.


For example, the notes might specify the junction box size and wires used. Consider the last point “10. 6x6x4” Junction Box. Run one 2” conduit to roof parapet junction box.” This line tells us that the height and width of the junction boxes are 6 inches and depth as 4 inches.


Section drawings provide more information on how a building, interior space, or equipment is installed. It may be divided into one or more multiple views through the assembly in a vertical direction. Section drawings take such an imaginary slice through an object or building.


Section drawings of electrical plans provide details on heights and relationships between floors, ceilings, spaces, walls, and equipment locations above one another. Two or more sections are often provided at 90 degrees to one another to give additional information.



The commercial buildings consist of multiple similar areas like apartments and hotel rooms. The multiple area floor plans are represented on drawings by a code or reference name on the floor plan. In electrical plans all the wiring layout are found in these plans.


It is helpful to find the correct location of pipes, wires, duct, and fire fighting from the main connection lines. As seen in the image, the unit plan provides the detailed view of the electrical layout used in the floor plan of respective area. Let’s summarize how to read the plan while utilizing all the sources.


The checklist for referring electrical plans are:

  • Check for the title of the drawing, note its scale, and reference to the orientation or directions,

  • Check for symbols, abbreviations, and legends,

  • Readout general notes and respective plan notes for more details,

  • Refer to schedules or specifications before referring any equipment on the plans,

  • Check thermostat locations in all the floor plans to coordinate electrical, furniture, and wall layout,

  • Check the drawings with the reflected ceiling plan(RCP) and other trades drawings to find proper locations and routings,

  • Check the drawings of panels and connection board to access the power supply for equipment and fixtures,

  • Check the details, sections, riser diagrams, and enlarged plans for more details, and

  • Finally, during maintenance, refer to the final set of drawings As-Built drawings.

The electrical floor plans and other electric plans consist layout of wiring routing, equipment location, and connection point inside the ceiling. The electrical plans include plan notes that consist of additional details required at the time of installation.





 

Question #1: Where are general notes provided on electrical plans?

  1. Last page

  2. Not provided

  3. On plans

  4. First page

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Answer: First page

The general notes are provided on the first page of electrical plans or any plans.


Question #2: Electrical systems such as lights, distribution panels, and fixtures are denoted using various symbols with descriptions provided in:

  1. Legends

  2. General notes

  3. Abbreviations table

  4. Table

Scroll down for the answer...














Answer: Legends

Electrical systems such as lights, switches, circuit breakers, distribution panels, and fixtures are denoted using various symbols described in legends.


Question #3: Where the details of text written beside several symbols used in the electrical drawings are found in:

  1. Legends

  2. Floor plan

  3. Plan notes

  4. Abbreviations table

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Answer: Abbreviations table

The abbreviations table provides the details of text written beside several symbols used in the electrical drawings.


Question #4: In the electrical drawings, details of fixtures used on the plans are provided in:

  1. Symbols

  2. General notes

  3. Schedules

  4. Tables

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Answer: Schedules

The electrical drawings include schedules for the light fixture, equipment, and load details. Schedules help to know details of the equipment or item used on the electrical plans.


Question #5: _____ helps to measure the size, length, and distance of the equipment provided on the plans.

  1. Sheet number

  2. Title block

  3. Details

  4. Scale

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Answer: Scale

The scale provided on the plan helps to measure the size, length, and distance of the equipment.


Question #6: The notes available on the electrical drawing sheet around the plan are known as:

  1. Office notes

  2. Plan notes

  3. General notes

  4. Copy notes

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Answer: Plan notes

The notes available on the electrical drawing sheet around the plans are known as plan notes.


Question #7: Which drawings provide more information on how a building, interior space, or equipment is installed?

  1. Equipment plan

  2. Elevation drawings

  3. MEP drawings

  4. Section drawings

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Answer: Section drawings

Section drawings provide more information on how a building, interior space, or equipment is installed.


Question #8: The steps for referring electrical plans include: (Select all that apply)

  1. Check for the title of the drawing

  2. Refer architectural notes on the electrical plan

  3. Plan stages need not be referred

  4. Check for legends, symbols, and abbreviations

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Answer: Check for the title of the drawing

Check for legends, symbols, and abbreviations

The checklist for electrical plans are:

  • Check for the title of the drawing, note its scale, and reference to the orientation or directions,

  • Check for symbols, abbreviations, and legends, and

  • Readout general notes and respective plan notes for more details.


Question #9: The steps for referring electrical plans include: (Select all that apply)

  1. Check for city site plan

  2. Refer to enlarged plans and sections for more details

  3. During maintenance, refer to the final set of drawings As-Built drawings

  4. Check for plumbing fixtures routing

Scroll down for the answer...















Answer: Refer to enlarged plans and sections for more details

During maintenance, refer to the final set of drawings As-Built drawings

The checklist for referring electrical plans are:

  • Check the drawings of panels and connection board to access the power supply for equipment and fixtures,

  • Check the details, sections, riser diagrams, and enlarged plans for more details, and

Finally, during maintenance, refer to the final set of drawings As-Built drawings.




1 Comment


This is a very informative guide to understanding electrical drawings and blueprints!  The breakdown of the different components, like legends and schedules, is helpful for anyone who wants to learn how to "read" these electrical plans.

Having a clear understanding of electrical symbols is especially important.  The blog mentions that these symbols can sometimes be quite complex.  Are there any resources you would recommend for learning more about common electrical symbols used in blueprints, besides the legend provided on the specific drawing itself?

Overall, this is a great resource for anyone who wants to gain a basic understanding of electrical drawings. Thanks for sharing!

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