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Reference

Components & Inputs

Every device in the Sandbox and on a real control panel — what it is, how it behaves, and where you'd use it. Keep this open while you build.

Power & Loads Push Buttons Switches & Selectors Sensors Relay Contacts & Coils Switching & Protection

Power & Loads

Power Source

Supply

The origin of all current in the circuit. Provides a hot leg (or legs) and a return. Everything else just makes or breaks the path between them.

Systems120V 1φ (L1,N) · 120/240V 1φ (L1,L2,N) · 120/240V 3φ (L1,L2,L3,N) · 480V 3φ (L1,L2,L3) · 480V 3φ+N · 480V 1φ (L1,L2)
UseSet this first — it defines the voltage every load is judged against and the conductor colors.

Light / Pilot Light

Load · Indicator

A load that lights when its circuit completes. A pilot light is the panel version — used for status, not illumination (green = running, red = stopped/fault, amber = warning).

BehaviorOn only when hot reaches one side and return reaches the other at the right voltage.
UseStatus indication, run/stop lights, fault annunciation.

Motor

Load

The thing that does the mechanical work. Rated for a specific voltage and phase. Over-voltage faults it (🔥); under-voltage means it won't run properly.

BehaviorRuns when fed at its rated voltage through a complete path (usually via a contactor).
UsePumps, fans, conveyors, compressors — anything that turns.

Coil (relay/contactor coil)

Control output

An electromagnet. When its circuit completes, it energizes and pulls in every contact and contactor that shares its letter. The heart of relay logic.

LetterGive it a letter (M, CR1, etc.); contacts with the same letter follow it.
UseTurns a small control signal into the muscle to switch big loads or many contacts.

Contactor (3-pole)

Power switch

A heavy-duty relay built to switch motor-level power. Three main poles (L1/L2/L3 → T1/T2/T3) slam closed together when its matching coil energizes.

ControlDriven by a separate Coil sharing its letter — coil energizes, poles close.
UseSwitching power to motors and large loads from a low-power control signal.

Transformer (control transformer)

Power conversion

Steps voltage down (e.g. 480V → 120V). Primary (H1/H2) takes the high voltage; secondary (X1/X2) becomes a new source at the lower voltage to power the control circuit.

UseKeeps the control circuit (buttons, coils, pilot lights) at a safe, friendly voltage.

Push Buttons

Push Button — Normally Open (NO)

Momentary input

NOOpen at rest; closes only while you hold it, springs back when released. Passes current only while pressed.

UseSTART buttons. A momentary tap kicks off a circuit that a seal-in then holds.

Push Button — Normally Closed (NC)

Momentary input

NCClosed at rest; opens while you hold it. Passes current until pressed.

UseSTOP buttons and e-stops. Pressing it breaks the circuit and drops the coil.

Push Button — Two-Block (NO + NC)

Momentary input

NCNOOne button operating two contact blocks at once. Press it and the NC block opens while the NO block closes — simultaneously.

UseForward/reverse and jog circuits where one button must make one path while breaking another (built-in interlocking).

Switches & Selectors

Single-Pole Switch

Maintained input

A simple on/off switch that holds its state. Open or closed until you flip it.

UseDisconnects, simple manual control, two-wire control of a load.

3-Way Switch

Maintained · SPDT

A single-pole, double-throw switch: a common terminal that connects to one of two travelers. Flipping it moves the connection from one traveler to the other.

UseControlling one light from two locations (a pair of 3-ways). Also "either/or" routing in control logic.

4-Way Switch

Maintained · crossover

A crossover switch with two inputs and two outputs. It either passes the travelers straight through or crosses them, swapping the path.

UsePlaced between two 3-ways to add more control locations — one light from three, four, or more spots.

Selector Switch (Hand-Off-Auto)

Maintained · 3-position

A maintained rotary switch. A common terminal routes to one of two outputs (HAND or AUTO) or to neither (OFF).

UseChoosing between manual operation, off, and automatic control on the same circuit.

Sensors (automatic inputs)

These are switches operated by a physical condition instead of a hand. Each can be wired NO or NC depending on what you want it to do.

Limit Switch

Mechanical sensor

Trips when a moving machine part physically contacts its lever or plunger. Tells the circuit "something reached this position."

UseEnd-of-travel stops, position detection, sequencing (a part arrives → next step starts).

Float Switch

Level sensor

Operated by a liquid level via a float. Changes state as the level rises or falls.

UseSump and fill pumps, tank level control — run the pump when level is high (or low), stop at the setpoint.

Proximity Switch

Non-contact sensor

Detects a nearby object without touching it (inductive for metal, capacitive for most materials). No moving parts to wear out.

UsePart-present detection, counting, position sensing in fast or dirty environments.

Pressure Switch (real-world)

Pressure sensor

Closes or opens at a set pressure. (Wire a maintained switch in the Sandbox to represent it.)

UseAir compressors (cut-in/cut-out), pump protection, hydraulic systems.

Temperature Switch / Thermostat (real-world)

Temperature sensor

Changes state at a set temperature.

UseCalling for heating/cooling, over-temp protection, fan control.

Relay Contacts & Coils

NO Contact (relay contact, normally open)

Control output

NOAn auxiliary contact controlled by a coil, not by hand. Open until its coil energizes, then it closes. Assign it the coil's letter.

UseSeal-in/holding contacts, turning on additional rungs when a coil energizes, interlock logic.

NC Contact (relay contact, normally closed)

Control output

NCClosed until its coil energizes, then it opens. Assign it the coil's letter.

UseElectrical interlocks (one coil's NC contact prevents another from energizing), shutting down rungs when something turns on.

Switching & Protection

Overload Relay

Motor protection

Senses motor current through heaters in the power circuit. On a sustained overcurrent it trips, opening its NC auxiliary contact in the control circuit to drop the coil and stop the motor.

UseProtecting motors from burning out. Always wired into the control circuit via its aux contact.

Fuse / Circuit Breaker (real-world)

Overcurrent protection

Opens the circuit on a fault or short. A fuse is one-time (replace it); a breaker resets.

UseProtecting conductors and equipment from short circuits and overcurrent.