The use of electrical fuses in domestic wiring is

Analyze the question: It asks about the purpose of a fuse in the wiring of a house.

Concept: A fuse is a safety device made of a short piece of thin wire with a low melting point. It is connected in series with the live wire. When the current in the circuit becomes too high, for example from a short circuit or an overload, the wire heats up, melts and breaks the circuit. This stops the flow of current and protects the appliances and the wiring from overheating and fire.

Going through the options:

• A. To prevent an electrical shock: Incorrect. A fuse protects against excess current. Earthing and insulation are what protect against shock.
• B. To supply electricity to all appliances: Incorrect. Supply comes from the mains, not from the fuse.
• C. To allow electricity to flow easily: Incorrect. A fuse adds a point of weakness to the circuit on purpose. It does not help current flow.
• D. To cut off the mains supply if too high a current flows: Correct. This is exactly what a fuse does. (The option has a typo, "it" instead of "if".)
• E. To fuse all the circuit into one: Incorrect. This is a play on the word "fuse" and has no meaning in physics.

Answer: D.

Exam tip: Remember "Fuse = Fire protection." A fuse is always connected in series with the live wire and breaks the circuit when the current exceeds its rating. Its rating should be slightly higher than the normal working current of the appliance. Related ideas that often appear in NECO and JAMB are choosing the correct fuse rating with I = P/V, and the function of earthing.