Heating, Ventilation, and Air Conditioning (HVAC ) Electrical Practice Test

What is commonly indicated by a reading of zero ohms on an ohmmeter?

1. Open circuit

2. Shorted circuit

3. Normal operation

4. High resistance

The correct answer is: Shorted circuit

A reading of zero ohms on an ohmmeter indicates a shorted circuit. This means that there is a direct path for electrical current to flow, typically with little to no resistance. In an electrical circuit, this condition suggests that two conductive parts are unintentionally connected together, potentially causing excessive current to flow, which can lead to component damage or failure. In contrast, an open circuit would show infinite resistance or very high resistance, indicating that there is no path for current to flow. Normal operation usually implies that the resistance is within a specified range for the given component, indicating that it is functioning properly without shorts or open conditions. High resistance would show a value significantly greater than zero, indicating a normal resistance level but not a short circuit. Thus, a zero ohm reading is a clear indicator of a shorted circuit condition.