A 2 way micro switch is not a precise, universal wiring designation. Depending on context, “2 way” may describe an actuator with two positions or a switch that changes between contact paths. The phrase alone does not identify the terminals or establish a wiring diagram. To identify a particular switch, separate its mechanical positions from its electrical contact states, then check the terminals in each state against the device’s markings or documentation.
For a basic verification, disconnect the circuit from power and, where practical, isolate the switch from the rest of the circuit. Use an appropriate continuity-testing method across terminal pairs while manually releasing and actuating the switch. Record what changes in each state. Treat those observations as evidence about that switch, not as a universal interpretation of “2 way.”
What does 2 way micro switch mean?
“2 way” is an informal or context-dependent phrase when applied to a micro switch. One person may use it to describe two actuator positions, such as released and pressed. Another may use it to refer to switching between contact paths. These are different descriptions: one concerns mechanical movement, while the other concerns electrical behavior.
Neither meaning, by itself, tells you how a particular switch is internally arranged. The phrase does not define a universal wiring configuration, identify which terminal is common, or establish which contacts are closed in either actuator state. Two switches described with the same phrase could therefore require their own markings and documentation to determine terminal behavior.
Start identification with the switch itself rather than the phrase used to describe it. Look for molded or printed terminal symbols, labels, or a diagram, and compare them with the switch’s documentation. If the markings are missing or unclear, do not fill in the gaps based only on the number of terminals, their physical positions, or the words “2 way.” Verify the electrical states directly while the switch is unpowered, and leave any unresolved terminal identity unresolved until supported by reliable device information.
This distinction matters when identifying a switch for a circuit. A description that indicates two actuator positions is not proof that the device has a particular contact arrangement. Likewise, observing a change between contact paths does not establish that the switch is suitable for a particular application. Mechanical description, terminal behavior, and circuit suitability are separate questions.
Actuator positions are not the same as terminal states
The actuator is the part moved by an external force, such as a plunger or lever. A switch may have a released state and an actuated state. Pressing or releasing the actuator can change which contacts are electrically connected, but the physical position and the electrical contact state are not interchangeable terms. Verify the change on the actual device rather than assuming what its movement means from its name.
Normally open (NO) and normally closed (NC) describe contact states relative to the switch’s unactuated condition. NO identifies a contact path that is open in that condition; NC identifies one that is closed in that condition. “Normally” here refers to the unactuated state, not to a prediction about how the switch will be used or which state is more common in an application.
A common terminal, abbreviated COM, is the common terminal where present. The labels COM, NO, and NC are terminal terminology, not names for actuator positions. A switch may use some or all of these labels, so check the exact device schematic rather than assuming every switch has the same terminal set or arrangement.
For terminology tied to actuator travel, pretravel runs from the free position to the operating position. Overtravel runs from the operating position to the extreme permitted actuator position. Those travel descriptions do not, on their own, identify which terminals are connected. They describe actuator movement, while NO, NC, and COM describe terminal or contact terminology.
Keeping the two descriptions separate makes observations easier to record. Note whether the actuator is released or actuated, then separately record which terminal pairs show continuity. Do not substitute “pressed” for NO or “released” for NC: the NO and NC labels refer to the contact state relative to the unactuated condition, and the actual terminal behavior should be checked on the specific switch.
How to identify a 2 way micro switch by its terminals
Begin with the markings on the switch and its documentation. Look for COM, NO, and NC symbols or labels, and check the device schematic for their intended meaning. Generic changeover terminology can help interpret these labels, but the exact switch schematic remains the reference for that device. Do not assume that a terminal’s location on the body identifies its function.
For an electrical check, first disconnect power to the circuit. Where practical, isolate the switch from the surrounding circuit so other connected paths do not affect the observation. The evidence here does not define a complete test procedure, meter setting, or special test condition, so follow the test instrument’s instructions and the switch’s documentation rather than treating this article as a detailed instrument procedure.
With the switch unpowered, check continuity across terminal pairs in the released state, then manually change the actuator state and check again. Record the observed result for each pair and state. A pair that changes from open to connected, or from connected to open, shows a change in terminal behavior; do not assign a terminal label from physical position alone. Compare the recorded behavior with the markings or documentation. If the observations conflict with the supplied diagram, or the labels cannot be verified, do not assume the identity of the terminals.
This state-based approach answers a bounded question: which terminal pairs behave as connected or open in the observed actuator states? It does not establish the switch’s ratings, suitability for a circuit, or compatibility with a replacement. Nor does a two-state observation turn “2 way” into a standard wiring description. Keep the observations attached to the specific switch and its markings.
Related guides
Check ratings and safe use before choosing a replacement
Do not test or change wiring on an energized circuit. Disconnect power before inspecting terminal behavior, and avoid treating an in-circuit observation as proof of the switch’s own contact state when other circuit paths may be involved. If the switch cannot be isolated or identified with confidence, the available evidence is not enough to resolve its terminal behavior safely.
Before choosing a replacement, compare the requirements supported by the device documentation and the application. These include electrical ratings, contact configuration, actuator geometry, and operating requirements. Matching the terminal count, external appearance, or physical fit alone does not prove compatibility. A switch that appears similar may have different terminal behavior or requirements, and the supplied evidence does not establish suitability for any particular appliance or vehicle.
Electrical ratings are not universal switching capacities. Rating values are specification-sheet requirements tied to stated load and test conditions. Check the applicable specification sheet and the stated conditions before deciding whether a switch is suitable for a circuit. Do not infer a rating from the phrase “2 way,” the terminal labels, or the result of a continuity check.
The practical conclusion is narrow: use “2 way” only as a clue to ask what the description means. Identify actuator states separately from contact states, verify terminal behavior while the switch is unpowered, and compare what you observe with that switch’s markings and documentation. Leave wiring layout, ratings, and application suitability unresolved unless the device information supports them.
This concludes the explanation of 2 way micro switch.
Sources and references
- Defense Logistics Agency ASSIST: MIL-PRF-8805K: Switches and Switch Assemblies, Sensitive, Snap Action, General Specification For
- Wikipedia: Miniature snap-action switch