• Open-circuit scuba, a type of SCUBA-diving equipment where the user breathes from the set and then exhales to the surroundings without recycling the exhaled air
• Open circuit test
  Open circuit test
  The Open circuit test, or "no-load test", is one of the methods used in electrical engineering to determine the no load impedance in the excitation branch of a real transformer.-Method:...
  
  , a method used in electrical engineering to determine the impedance in the excitation branch of a real transformer
• Open-circuit voltage
  Open-circuit voltage
  Open-circuit voltage is the difference of electrical potential between two terminals of a device when there is no external load connected, i.e. the circuit is broken or open. Under these conditions there is no external electric current between the terminals, even though there may be current...
  
  , the difference of electrical potential between two terminals of a device when there is no external load connected
• Self-contained breathing apparatus, used in open-circuit SCUBA
• An electric circuit is an "open circuit" if it lacks a complete path between the positive and negative terminals of its power source

See also

• Closed-circuit (disambiguation)
• Short circuit (disambiguation)
  Short circuit (disambiguation)
  A short circuit is a type of malfunction of an electrical circuit.Short Circuit may also refer to:*Short Circuit, a film about a robot that comes to life**Short Circuit , based on the film**Short Circuit 2...
  
  
• Open system (disambiguation)