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Overcurrent Protection
13 questions By Tony R. Kuphaldt
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Question 1 of 13
What hazards might be posed by a circuit with excessive current going through its conductors (excessive as defined by the conductors’ ampacity)? In other words, what would be bad about a wire carrying too much current?
Also determine which type of component fault, an open or a short, would most likely be the cause of excessive current in a circuit.
Reveal answerOverloaded wiring gets hot - perhaps enough to start a fire.
A shorted component could cause excessive current in a circuit, but an open fault will result in less (or no) current.
Notes:Even if an overloaded wire does not get hot enough to ignite nearby combustible material, there are other ill effects of conductor overloading. Challenge your students to think of some other, negative consequences which may result from conductor overloading.
One of the goals of this question is for students to be able to distinguish between open and short component faults.
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Question 2 of 13
Explain the construction and purpose of an electrical fuse.
Reveal answerA fuse is a thin piece of metal designed to melt into two pieces in an overcurrent condition.
Notes:Fuses come in many different styles and sizes. It would be good to have an array of fuses available for your students to see and hold during discussion time.
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Question 3 of 13
What is the difference between a fuse and a circuit breaker?
Reveal answerA fuse is for one-time use, while a circuit breaker may be re-set and used repeatedly.
Notes:There used to be a time when overcurrent protection for household circuits was primarily provided by fuses. In modern times, however, fuses are obsolete for household wiring - circuit breakers have completely taken their place. Discuss the relative advantages and disadvantages of these two overcurrent protection technologies.
