For maximum safety of equipment, overload relays should be

• A. Manual reset type
• B. Included in contactors
• C. Not affected by motor current
• D. Automatic reset type

Answer: (A)

The key safety idea is that a fault condition should not be allowed to end by itself and trigger an automatic restart. A manual reset overload relay forces a deliberate action by the operator to restart the circuit after a fault is cleared, ensuring someone has verified that conditions are safe before reenergizing the motor. This prevents the motor from restarting immediately after an overload, which could cause further damage or danger.

Why this is the best choice: requiring a manual reset adds a verification step, reducing the chance of re-energizing equipment under unsafe conditions. It puts control in human hands to assess the fault, perform maintenance if needed, and only then restart.

Why the other ideas aren’t as effective for safety: simply being integrated into contactors doesn’t guarantee a safer restart process; it’s about the reset behavior, not just wiring. A device that’s not affected by motor current wouldn’t provide proper protection at all, since overcurrent triggering is how overload protection detects faults. An automatic reset type could restart the motor without any operator acknowledgment, potentially re-energizing a fault condition and risking damage or injury.