Alabama Contractors License Practice Exam

What is the minimum interrupting rating for electrical equipment intended to interrupt current at fault levels?

1. 1 ampere

2. 5,000 amperes

3. 10,000 amperes

4. 15,000 amperes

The correct answer is: 10,000 amperes

The minimum interrupting rating for electrical equipment intended to interrupt current at fault levels should be significant enough to handle the maximum fault currents that could occur in a system, while ensuring safety and reliability. In general, a rating of 10,000 amperes is recognized as a common threshold in various standards and codes, which equips electrical devices to effectively interrupt and manage electrical faults without failing. This rating is designed to provide adequate safety margins for various applications, including commercial and industrial settings where higher fault currents can be expected. It allows the equipment to operate without risking catastrophic failure or posing hazards to personnel or property during an electrical fault. Higher interrupting ratings (such as 15,000) may be appropriate for more specific or heavy-duty applications, but the 10,000-ampere rating is widely accepted in regulations for broader usage. This is why the choice indicating 10,000 amperes is considered appropriate for minimum interrupting ratings in standard contexts.