What safety feature must be provided for fixed electric welders?

Fixed electric welders must have a safety feature that includes a switch or circuit breaker to disconnect from the supply circuit in an emergency. This feature is essential for the safety of the operator and those working in the vicinity of the welding operation. In the event of an emergency, such as a malfunction or accidental contact with live parts, having the ability to quickly disconnect power ensures that any potential hazards can be mitigated immediately.

It is crucial for any electrical equipment to have such emergency disconnection capabilities to prevent injuries, equipment damage, or fires. This safety measure is part of standard safety protocols in welding to ensure a safe working environment.

Other options, while they may enhance safety or functionality, do not fulfill the specific emergency disconnection need that is crucial for fixed electric welders.