Is it required to maintain protective devices so they can withstand and interrupt available fault current?

• A. True
• B. False
• C. Not specified
• D. Optional under certain conditions

Answer: (A)

Protective devices must be kept in a condition that ensures they can both withstand the forces of a fault and interrupt the fault current if one occurs. The available fault current is the maximum current that could flow through the system during a short circuit, depending on the source and network configuration. Over time or after changes to the system, that fault current can increase, so devices must be properly rated and tested to break that current reliably. If maintenance is neglected, a breaker might fail to trip, or trip too slowly, allowing excessive current to flow, which can cause severe equipment damage, arcing, or injury. Regular maintenance, testing, and verification against the system’s available fault current are essential to keep protection effective and safe.