Nodes, dots and what a meter sees
Three resistors and a meter: what a node is, why a dot means joined, and how to read the voltage a drawing predicts before you measure it.
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Reading electrical drawings
Symbols, schematics, wiring diagrams, ladder diagrams, one-lines, floor plans and panel schedules, each read on the page and then proved on a circuit that runs.
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What you will build
2 projects, built step by step
8 lessons in 6 chapters, about 5 hours on a simulated breadboard. Free, in your browser, every step checked by the simulator.
Floor plans: a hallway with three switches
Read the switch symbols on an electrical floor plan, S, S3 and S4, and prove a three-switch hallway on a logic model: any switch flips the light.
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Chapter by chapter
Each lesson opens when the one before it is done, and each chapter ends in a project.
Chapter 1
Symbols and schematics
The alphabet of a drawing, and what a node really is.
- Open150 XP
Symbols: the alphabet of a drawing
Read a first schematic symbol by symbol, a supply, a switch, a resistor, an LED and ground, then prove each one on the circuit it describes.
0 of 5 steps
- ProjectLocked300 XP
Nodes, dots and what a meter sees
Three resistors and a meter: what a node is, why a dot means joined, and how to read the voltage a drawing predicts before you measure it.
0 of 5 steps
Chapter 2
Wiring diagrams
Where every wire lands, on a three-way switch.
- Locked150 XP
Wiring diagrams: where every wire lands
A three-way switch drawn two ways: as a schematic that shows how it works and as a wiring diagram that shows which terminal every traveler lands on.
0 of 5 steps
Chapter 3
Ladder diagrams
Rails, rungs, contacts, coils and the seal-in.
- Locked175 XP
Ladder diagrams: rails and rungs
The drawing every industrial electrician reads: two rails, rungs of contacts and coils, normally open and normally closed, and the seal-in that keeps a motor running.
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Chapter 4
One-lines and floor plans
A whole power system on one line, and switches on a plan.
- Locked175 XP
One-line diagrams: a whole system on one line
A generator transfer switch read from its one-line: two sources, two interlocked contactors and a load, then an outage and a transfer on a low-voltage model.
0 of 6 steps
- ProjectLocked300 XP
Floor plans: a hallway with three switches
Read the switch symbols on an electrical floor plan, S, S3 and S4, and prove a three-switch hallway on a logic model: any switch flips the light.
0 of 5 steps
Chapter 5
Panel schedules
What every breaker feeds, and how loaded each leg is.
- Locked175 XP
Panel schedules: what every breaker feeds
Read a panel schedule, circuit numbers, breaker sizes, loads and legs, then watch a monitor flag a circuit over 80 percent, an overload and an unbalanced panel.
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Chapter 6
Boss project
Build a motor starter from its ladder drawing.
- Locked200 XP
Boss: build it from the drawing
The motor starter with three control wires missing. Read the ladder, draw each wire where the drawing says, prove the seal-in and the stop, then build revision B.
0 of 7 steps
Syllabus
Every lesson in the course
All 8 lessons, in order, each with what it covers. Any of them opens in the editor right away.
Symbols and schematics
- Symbols: the alphabet of a drawingRead a first schematic symbol by symbol, a supply, a switch, a resistor, an LED and ground, then prove each one on the circuit it describes.
- Nodes, dots and what a meter seesThree resistors and a meter: what a node is, why a dot means joined, and how to read the voltage a drawing predicts before you measure it.
Wiring diagrams
- Wiring diagrams: where every wire landsA three-way switch drawn two ways: as a schematic that shows how it works and as a wiring diagram that shows which terminal every traveler lands on.
Ladder diagrams
- Ladder diagrams: rails and rungsThe drawing every industrial electrician reads: two rails, rungs of contacts and coils, normally open and normally closed, and the seal-in that keeps a motor running.
One-lines and floor plans
- One-line diagrams: a whole system on one lineA generator transfer switch read from its one-line: two sources, two interlocked contactors and a load, then an outage and a transfer on a low-voltage model.
- Floor plans: a hallway with three switchesRead the switch symbols on an electrical floor plan, S, S3 and S4, and prove a three-switch hallway on a logic model: any switch flips the light.
Panel schedules
- Panel schedules: what every breaker feedsRead a panel schedule, circuit numbers, breaker sizes, loads and legs, then watch a monitor flag a circuit over 80 percent, an overload and an unbalanced panel.
Boss project
- Boss: build it from the drawingThe motor starter with three control wires missing. Read the ladder, draw each wire where the drawing says, prove the seal-in and the stop, then build revision B.
Kits
Build it on your bench too
Every lesson runs in the simulator with nothing to buy. When you want the real thing, these kits have the parts.
Find your kit
Pick the starter kit you own and run every lesson in its manual with the same parts on the same pins.
See every kitQuestions
About Reading electrical drawings
Is Reading electrical drawings free?
Yes. All 8 lessons of Reading electrical drawings are free and run in your browser, with nothing to install and no parts to buy before you start.
Do I need any parts?
No. Every circuit is built on a simulated breadboard, and the simulator checks each step as you go. When you want to build it for real, the same parts and wiring work on a real bench.
How long does Reading electrical drawings take?
About 5 hours: 8 lessons in 6 chapters, each one a few short steps. Your progress is kept, so you can stop after any lesson and pick up where you left off.
What will I build?
Each chapter ends in a project that puts it together: Nodes, dots and what a meter sees and Floor plans: a hallway with three switches.
Where do I start?
With "Symbols: the alphabet of a drawing", and each lesson builds on the one before it. New to circuits? Electronics basics is the course that starts from zero.