Which ohmmeter reading indicates a fuse is bad?

A fuse is designed to provide a safety feature in an electrical circuit by allowing current to pass through normally but breaking the circuit when the current exceeds a certain limit, typically due to a fault or overload. When measuring a fuse with an ohmmeter, a good fuse will typically show a very low resistance reading, usually close to 0 ohms, indicating that it can conduct electricity effectively.

A reading of infinity, often represented as "OL" for open line, indicates that there is no continuity through the fuse, meaning it has failed. This lack of continuity confirms that the fuse has blown and is no longer functioning, thus making it unsafe for use in the circuit. Conversely, lower resistance values such as 1 ohm or 10 ohms suggest that the fuse is still intact, as these readings indicate that the fuse can still allow current to pass. Therefore, the reading of infinity (OL) is the definitive indicator that a fuse is bad.