Electric Symbols

by admin on October 16, 2012

Electric Symbols Library Key for House Plan Drawings – When drafting up a plan for any building, electrical symbols are used to represent any lighting arrangements which will be incorporated into the house, including all fixtures, outlets and switches.

These symbols are not standardized although fixture templates are available to refer to when drafting and these symbols are usually drawn freehand unless using computer-aided drafting and design (CADD).

Most drafts will have a symbol legend or list for cross reference as many designers modify the basic symbols to reflect their personal needs.

Many of the symbols look quite similar as the basis is usually a circle or square but it is the insertion of an additional line, dot, shading, letters, numbers etc that give meaning to the symbol and so a good starting point when learning about electrical symbols is to familiarize yourself with the basic structures of the differing common symbols and their meanings.

The symbols, lettering for switches and related notes should all be 3mm (1/8”) high and the electrical layout should not detract attention away from or clutter up the main plan but rather be a smaller add-on informational side piece.

In general, the switch symbols are drawn perpendicular to the wall so it is read from the right side or the bottom of the sheet and if a fixture requires specific requirements, a local note outlining the situation may be placed next to the outlet.

Depending on your employers’ preference, the switch relay can either intersect the symbol at right angles to the wall or by starting the relay next to the symbol but you must stay consistent throughout the whole project.

Small yet powerful halogen recessed light fixtures are also popular as they provide luminous illumination as well as being energy efficient but in most cases, i.e. in a standard kitchen, you will be required to strategically place six or more of these fixtures to ensure quality adequate lighting whilst avoiding shadows at counter areas.

When manually drafting such plan, you must first begin with a base drawing of the floor plan with all of the main components like walls, doors, cabinets, windows, fireplace and stairs in place.

Then, using a sharp mechanical pencil, add the switch and light fixture locations ensuring that all circles etc adhere to the 3mm rule as if they are too big, they will distract from the drawing and if too small they will be difficult to decipher.

If using CADD, you can use the electrical symbol library to simply insert the symbols.

Add electrical circuits and switch legs between the switches and fixtures, using an irregular curve (or a dashed arc line if using CADD) and then place all electrical outlets e.g. television onto the plan.

It is always a good idea to provide the drafts well in advance of the scheduled installation time so that the installer(s) can familiarise themselves with the specifications and details of the job and can request further directions or clarifications if necessary in preparation of the task i.e. if the drafter has written that mounting heights of devices are to be ‘verified and modified as directed’ then the installer will need sufficient time to identify this and liaise with the designer to rectify the issue.

Some Example of Electric Symbols

Add some of these electrical components to your floor plan to show how you intend to use electrical appliances in your house.

When starting the electrical plan begin in the kitchen and start with fused spur points located roughly where you would expect to use the oven and electric hob.

Note: right click to view electric symbols with larger scale