How do you differentiate between a short circuit and an open circuit in wiring?

• A. Short circuit has abnormally low resistance causing continuous fault; open circuit has broken path causing no signal or supervision.
• B. Short circuit has high resistance.
• C. Open circuit has high resistance.
• D. Both are the same.

Answer: (A)

Short circuits and open circuits differ mainly in how they affect current flow and resistance. A short circuit creates a path of very low resistance, causing a large amount of current to flow and producing a continuous fault until protection trips. An open circuit has a broken path, so no current can flow and the circuit cannot power or supervise devices. The best choice describes both aspects together—low resistance with a continuous fault for a short, versus a broken path with no current for an open circuit. The other options misstate the resistance of a short, or only note high resistance for an open circuit, or claim they’re the same.