Fuses and circuit breakers are required to be marked with all but which of the following?

Fuses and circuit breakers are essential components in electrical systems, designed to protect circuits from overload and short-circuit conditions. They must be marked with specific information to ensure safe and effective operation. Among the listed options, the marking that is not required is resistance.

Fuses and circuit breakers are typically marked with their amperage rating, which indicates the maximum current they can carry before tripping. This is vital for preventing overheating and potential fire hazards. Voltage ratings are also necessary, as they denote the maximum voltage the device can safely handle, thereby preventing breakdowns in high-voltage scenarios.

In the case of short-circuit current ratings, these devices are often required to be marked with this information as well. It reflects their ability to withstand short-circuit conditions without failing, which is crucial for ensuring the overall safety and reliability of the electrical system.

Resistance, however, is not a typical marking on fuses and circuit breakers. These devices are not primarily defined by their resistance value in the same way that resistors are. Instead, their purpose and operation are far more concerned with managing current flow and preventing excess current from causing damage. Therefore, marking with resistance is unnecessary and not practiced in standard electrical requirements.