Murray State University School of Engineering CourseWiki

Electrical Diagram Types

Choose a drawing by the question it answers: appearance, connections, function, control logic, or physical location.

Choose the drawing for the job

Choose the drawing for the job

One electrical system can need several drawings. Start with the question: What does the part look like? Where does this wire go? How does the circuit work? Where does the equipment fit?

Choose the drawing for the question you need to answer.
TypeShowsUsually leaves outWho uses it, and when
PictorialRecognizable appearances of parts.Exact electrical behavior and hidden connections may be omitted.A beginner or assembler identifying parts before tracing connections.
BlockFunctions and the direction of signal or power flow.Individual terminals, component values, and return wires.A designer explaining a system before working out its circuits.
WiringConnections between terminals; wire identifiers and routing where specified.The reason the circuit behaves as it does; scale may be omitted.An assembler or service technician connecting or tracing wires.
SchematicElectrical function and connections using component symbols.Actual component positions, wire lengths, and enclosure geometry.A circuit designer or technician analyzing how a circuit works.
IC / PCB layoutPhysical geometry: a PCB has footprints, pads and copper traces; an IC layout describes structures and interconnect on a chip.A convenient explanation of circuit operation.A board or chip designer checking placement and routing before manufacture.
LadderRelay or PLC control logic arranged in rungs between rails.Exact equipment placement and wire routing.A controls technician tracing the conditions for an output.
LogicGates and the relationships between logical inputs and outputs.Power wiring, package pin locations, and physical placement unless added.A digital designer following Boolean decisions through a circuit.
Electrical floor planLocations of outlets, switches and fixtures on a building plan, interpreted with its legend.Internal circuit operation; complete routing may be on other drawings.An installer or building designer locating devices within rooms.
RiserDistribution between building levels and the equipment serving them.Detailed room layouts and exact conduit paths unless specified.A building electrical designer or installer coordinating distribution across floors.

Read the drawing title, legend, revision, and notes before treating a line or mark as an instruction. The same habit applies to mechanical drawings; see Choosing Drawing Views and The Alphabet of Lines.

Compare one circuit in pictorial, wiring, and schematic views; Interactive

Compare one circuit in pictorial, wiring, and schematic views

This teaching example connects a battery, switch, resistor, and LED in one loop. The resistor is in series with the LED. The drawings explain identity and connections; they do not specify a buildable parts list, resistor value, battery rating, or package pinout.

Pictorial view

B1 batteryS1 switchR1 resistorD1 LED
Recognize the parts. These simplified silhouettes are not package dimensions or a lead-identification guide.

Wiring view

B1 battery−+S1 switch12R1 resistor21D1 LEDKA
Follow terminals: B1+ → S1.1; S1.2 → R1.1; R1.2 → D1.A; D1.K → B1−. A means anode; K means cathode. Terminal names here belong to this example.

Schematic view

+B1 batteryS1 openR1 resistorD1 LED
Common symbols preserve the wiring connections. S1 is shown open. The LED cathode is the bar on the battery-negative side; the outward arrows identify light emission.

Block view

B1 batterySupplies energyS1 switchControls the pathR1 resistorLimits currentD1 LEDProduces light
Arrows show functional order, not individual conductors. The return conductor is omitted.

The wiring view retains every terminal connection. The block view deliberately removes that detail to explain each part's job. The schematic retains those connections while replacing part pictures with common symbols. Compare the three drawings together, or select one view to trace a part. On narrow screens the comparison stacks vertically.

For the electrical quantities and circuit behavior, continue to Current, Voltage, and Resistance, Series and Parallel Circuits, and AC and DC. For programmable control, see Microcontroller Basics. For work on real equipment, use Electrical Safety.

A layout, floor plan, and riser answer different location questions

A layout, floor plan, and riser answer different location questions

A PCB footprint is the land pattern where a component attaches to a board. Traces are the board's conductive paths. An IC is a chip; its internal layout is not the same drawing as the board that holds it.

A floor plan places devices in rooms. Its legend tells you what each mark means. A riser makes the relationship between building levels easier to follow. Neither should be treated as a complete installation instruction by itself.

Read control logic without assuming physical placement

Read control logic without assuming physical placement

A ladder diagram arranges control conditions and outputs in horizontal rungs between two vertical rails. A relay drawing and a PLC program may use a similar ladder shape, but a PLC instruction tests a stored state; it is not a picture of a physical contact.

L1 and L2 rails: S1 controls relay coil K1 on rung one; a normally open K1 contact controls lamp H1 on rung two.

Common relay forms, shown with S1 open and K1 de-energized. Closing S1 energizes K1; its normally open contact closes and H1 lights. Opening S1 releases K1 and turns H1 off. The shared K1 label links the coil and its contact; it is not a wire between rungs. This is a functional example, not an installation drawing.

A logic diagram emphasizes operations such as AND, OR, and NOT. It helps answer which combinations of inputs produce an output. The diagram may omit supply connections and package pin numbers, so it does not replace a wiring drawing.

Practice selecting a useful drawing; Practice

Practice selecting a useful drawing

Practice diagram selection

Continue with Reading Electrical Connections to recognize common component symbols, distinguish a joined wire from a crossing, and count electrical nodes.