Nfpa 70b circuit breaker testing

NFPA 70B is a standard for electrical equipment maintenance, and it provides guidelines for the testing and maintenance of electrical equipment, including circuit breakers. Here are some key points related to circuit breaker testing according to NFPA 70B:

Circuit Breaker Testing Requirements

  1. Visual Inspection: Before testing, perform a visual inspection of the circuit breaker to ensure it is properly installed, secured, and free from damage.
  2. Functionality Testing: Test the circuit breaker to ensure it trips properly when subjected to a fault current. This can be done using a test set or a simulated fault current.
  3. Trip Time Testing: Measure the trip time of the circuit breaker to ensure it trips within the specified time frame (usually 1-2 cycles).
  4. Hold Time Testing: Test the circuit breaker's hold time, which is the time it takes for the breaker to reset after a fault has been cleared.
  5. Dielectric Withstand Testing: Test the circuit breaker's dielectric withstand voltage to ensure it can withstand the voltage stress without breaking down.
  6. Mechanical Testing: Test the circuit breaker's mechanical operation, including the movement of the trip mechanism and the operation of the reset mechanism.

Testing Methods

  1. Simulated Fault Current Testing: Use a test set or a simulated fault current source to test the circuit breaker's trip time and hold time.
  2. Dielectric Withstand Testing: Use a dielectric withstand tester to apply a high voltage to the circuit breaker and measure its withstand voltage.
  3. Mechanical Testing: Use a mechanical testing device to test the circuit breaker's mechanical operation.

Testing Frequency

  1. Initial Testing: Perform initial testing of the circuit breaker during installation or when it is first put into service.
  2. Periodic Testing: Perform periodic testing of the circuit breaker at regular intervals, such as every 6-12 months, depending on the application and environmental conditions.
  3. Condition-Based Testing: Perform testing based on the condition of the circuit breaker, such as when it has been subjected to a fault or when it shows signs of wear or damage.

Record Keeping

  1. Test Records: Keep records of all testing performed on the circuit breaker, including the date, time, and results of the testing.
  2. Maintenance Records: Keep records of all maintenance performed on the circuit breaker, including the date, time, and type of maintenance performed.

By following these guidelines, you can ensure that your circuit breakers are properly tested and maintained to ensure safe and reliable operation.