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Dry contact may mean any of the following in electronics:

• No current: A dry contact is the synonym of volt free — it is not "wetted" by a voltage source. Dry contact can refer to a secondary set of contacts of a relay circuit which does not make or break the primary current being controlled by the relay. Usually some other contacts or devices have the job of starting or stopping the primary current being controlled. For example, a reed relay matrix switch is normally switched with all contacts dry. After the contacts are all connected, a wire spring relay is energized and connects a supervisory scan point, or main switch, through which the primary current being controlled then flows. Dry contacts are primarily employed in extra-low voltage (less than 50 V AC) distribution circuits.
• No mercury: The wet contact of a mercury-wetted relay gives certain operational advantages. Dry contacts means a relay that does not use mercury-wetted contacts.
• Dry joint: A dry contact can be confused with a dry joint, which is a type of poorly soldered joint in which the solder failed to wet the metal. These are liable to fail electrically. The term dry joint is also used less precisely to mean any sort of unsatisfactorily soldered joint.

See also

• Cold contact (disambiguation)

v t e Switch types
Analogue switch Banyan switch Battery isolator Cam switch Centrifugal switch Company switch Contact protection Crossbar switch Crossover switch Cryotron DIP switch Dry contact Electric switchboard Float switch Half-moon switch Humidistat Infinite switch Inertial switch Kill switch Key switch Knife switch Limit switch Latching switch Light switch Lightning switch Magnetic proximity fuze Magnetic starter Magnetic switch Mercury switch Miniature snap-action switch Motion-triggered contact insufficiency Optical switch Photoswitch Piezo switch Placebo button Pull switch Push switch Push-button Railroad switch Reed switch Rotary switch Sail switch Sea switch Sense switch Silicone rubber keypad Softswitch Spark gap Staircase timer Stepping switch Strowger switch Thermostat Time switch Touch switch Transfer switch Vacuum switch Vandal-resistant switch Wireless light switch Zero speed switch

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