Understanding Blueprints: Electrical Symbols Explained

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When we are starting to learn to read blueprints (and even after we know how really!), learning what all the symbols stand for can be quite confusing. In today’s episode of Electrician U, Dustin walks us through the different electrical symbols and their meanings.

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There are so many symbols that architects and engineers have access to use that there is no way for one video to cover them all. Also, something to keep in mind is that one architect/engineer may use one type for a device while another architect/engineer will use another. Look at the symbol legend for each set of drawings you have access to and see what is being used for. After some time reading drawings, you will learn the general types of symbols and be able to recognize them.
For the most popular general power type symbols, a circle with 2 lines represents a duplex receptacle. A circle with 3 lines represents a 220v receptacle. This can also be shown with the numerals 220 next to the symbol. A circle with 2 vertical and 2 horizontal lines represents a quad (or double duplex) receptacle. Many times, you will have the standard receptacle symbol with letters/words next to it denoting what type of receptacle. APP generally means a dedicated appliance, CT usually means it goes ABOVE counter height, GFCI (or GFI for us older folks) stands for a ground fault circuit interrupter receptacle (WP GFCI means it’s a weatherproof version).
Switching is usually denoted by a $ symbol. This is a generic version of a switch, and the letters/numbers are actually telling us what type of switch to install. If the $ has a 3 next to it, it is a 3-way switch while a $ with a 4 next to it is denoting a 4-way switch. A $D symbol means it is a dimmer, while a $OS stands for occupancy sensor switch (automatically turns on and off based on movement/lack of movement in a room). A KP symbol denotes a keypad location. Any time you see multiple $ symbols right next to each other that tells us how many switches are in a single location. So $$$$ would be a 4-gang switch location. Also, you may see letters next to certain switches in a single location, $$D$ for example. That means that the center switch in a 3-gang location is a dimmer.
Lighting fixtures also have their share of symbols. A circle with bisecting vertical and horizontal lines usually denotes a hanging type of light. If that symbol has the nomenclature Chan next to it, that stands for a chandelier while a Pend word is indicative of a pendant type of fixture. The same symbol with a square around it is a standard 5-6” can while a smaller version of the symbol will usually mean a mini can of the 3-4” version. A symbol that looks like an I beam (or a very elongated H) near cabinetry is an undercabinet fixture and will usually say UC or UCL next to the symbol. A variant of this is an above cabinet fixture and the symbol will state ACL. Track lighting is another popular symbol that looks like a simple line but will have triangles on the sides. These triangles are the actual track lighting heads themselves and the quantity that is shown on the symbol itself is the quantity they are expecting and facing the direction shown.
Another item to consider is that a commercial set of drawings will have more of an expanded version of these lists. Lighting fixtures will also usually have the fixture designation (type A or B, etc.) next to them as commercial projects tend to have a much higher quantity of light fixtures and many more styles than a residential. As always, refer to the fixture schedule and the symbol legend to get a better understanding of what is what.
We hope this has been an insightful look into what the electrical symbols mean for an electrical set of drawings. Is there a topic you would like to see discussed here on Electrician U? Leave us a comment in the comments section and let us know. Please continue to follow Dustin Stelzer and Electrician U as we are constantly updating our content to assist our followers in becoming the best electricians that they can be.

#electrician #electrical #electricity #understanding #blueprints #symbols #explained

[nunoaugusto]

I have to tell you something. I'm an apprentice, I have 30 years old so I don't have the same habits that the younger generation has. Besides that, I'm Portuguese, and I work with American and Hispanic people, so the language I kind of a barrier. With your videos, I started bending pipes by myself, checking the blueprint, boxes, mc cables, you name it. I knew all the materials in the first two or tree days because of you. I have to thank you, because with your help I'm getting to enjoy my work, and all I have is positive feedback. Thank you!

[BrawnyNerd]

Thanks for these videos Dustin. My program barely taught us how to read blueprints besides learning which symbols were what. Thank you again.

[victormendizabal]

You are the man thank you for my raise…..

[ybloc]

That's awesome! Could you do one on electrical diagrams for devices like generators or tracing wires through enclosures in a plant settings?

[RCRoads]

Thanks for sharing. Landscape stub is a new one for me. Great advice on running a 3 wire for landscape lighting.

[jasonh]

this was great. hope you will do more electrical symbols. I feel this is a overlooked for many Electrician influencers.

[darkflux]

the "NITCH" vs "NEESH" thing is an old argument. it is actually "NEESH", as niche is a French word, like quiche, but many Americans back in the day we did not have good schools, and so many people incorrectly pronounced the word as they read it in books as "NITCH" (and honestly, some people pronounced it that way just to be silly, but then others just thought that was how it was pronounced, and emulated that!). so the "American pronunciation" was actually an "American MISpronunciation" which just stuck and spread.

likewise with cache, another French root word. some people pronounce it "CAH-SHAY", but it actually doesn't have the little accent over the e, so it is just "CASH".

what's even worse is that English pulls from several different Latin-based languages: French, German, Spanish, Italian, and even Russian and others sometimes. so we get words like lich, which IS pronounced "LITCH", that throws all the other words into question, lol. i always look at the etymology or origin of the word. that often gives you an idea of how to pronounce it.

it reminds me of when i was a kid, my younger sister always tried to prove herself smarter than me, and this one time, she used a word "AW-REE". and i said to her "AW-REE?" and she said "Yeah, you know, when things go wrong, people say they have gone "AW-REE". and i said "You mean 'UH-RYE'?" and she said "NO! 'AW-REE'! A-W-R-Y!"

so it's a problem wether you are reading a book or hearing somebody say it to you directly. you never know who's right!

[Hitman..]

Thanks alot Dustin! You re the reason I am in the electrical trade (1.5 year non union and 10 months IBEW), I would ve been a plumber otherwise!

[brainmeat]

Thanks for the videos Dustin. I’ve really appreciated these recent blueprint tutorials you’ve been making.

Would love it if you made a video in the future explaining the process of running an entire commercial electrical project from start to finish. Perhaps some tips on staying organized and keeping a crew busy.

[Wizard__J]

Out here in Jersey we call them big eyes! Good video! It’s covered things I haven’t seen yet before, but extensive otherwise, and covered pretty much everything we do lol, ty for this

[dmtcodm]

pls do more of these videos, I really appreciate them

[garyarthurs]

I can’t speak to the history concerning how electricians may have used the terms 220 V and 240 V differently over time, but just a friendly tip that there is actually a difference. Check out IEEE Standard 141-1993 (aka The Red Book). See Table 3-1 on page 63 (pdf page 79 of 765). 240 is a “Nominal System Voltage” (aka the supply voltage). 220 is a “Utilization” voltage (aka what the equipment is designed to utilize). The idea is to account for voltage drop between the supply and the equipment. Thus the supply voltage of 240 V is higher than the utilization voltage of 220 V. The voltage drop can of course vary which is one reason the equipment is designed to operate over a range, e.g. 220 V +/- a percentage. Hope that helps.

[Sparky-]

Pro tip, if you have a fresh out of college engineer that thinks they know everything on the job site, make up random symbols and draw them in all the wrong spots. You'll get peace and quiet all day.

[ghostofgalileo]

Great explanation! Please make more of these.

[johnburgess]

I've wondered who (Electrician or Architect) is responsible for making sure lighting and electrical meets BUILDING codes? I know that you, as an electrician can wire an area that meets all electrical code, but the plans might omit required Exit signs, or satisfactory power capability for the likely intended purpose? And then the customer has to pay you again to come back out and fix THEIR design errors.

[benlawmusicofficial]

Killer video! This was super helpful! I gotta say thank you as I’ve learned so much from watching every one of your videos I can! Regarding this topic though, what about hardwired devices such as disposals, electric fireplaces, hot water heaters etc? How would you indicate those on a plan?

[alexandercruz]

Simply beautiful

Thanks for sharing!

[jongorman]

Huh..Always great content..our symbols up in the north run the other way...like 2 vertical lines in circle for duplex. Always great content and pretty cool to see how things are in other parts of the country

[mattdelaney]

A big thing happening in the industry with commercial, industrial and the addition of BESS systems is the need and requirements for As-Built drawings. Should get this discussion into your blue print videos. It's a big skill to have to keep track of and document dwg mark ups.

[refraf]

I don’t want to be an electrician I am however a dilettante lol . This video was incredibly clear for someone like myself who has little to no experience with blueprint reading to understand.