Breaker and Fuse Discrimination

Question 1

What is the purpose of a breaker and fuse?

Answer 1

• Breakers and Fuses are used to protect the power supply only
• They do not protect the item

Question 2

What is Breaker Discriminations?

Answer 2

• First breaker to trip is the MCCB
• Last breaker to trip is the Supply Breaker
• Breaker nearest the fault is the first
• Breaker furthest from the fault is the last

Question 3

What is Fuse Discrimination?

Answer 3

• Fuse nearest the fault is the first
• Fuse furthest from the fault is the last
• Multiple fuse panels in a circuit
  440V discrimination uses a ratio of 3:1
  115V discrimination uses a ratio of 2:1
• Mess deck kettle fault CANNOT trip a generator Supply Breaker