What does the rating on a fuse indicate?

• A. It indicates the fuse's voltage rating.
• B. It indicates the maximum current the fuse can carry before it opens.
• C. It indicates the time it takes to blow.
• D. It indicates the resistance of the fuse.

Answer: (B)

A fuse protects a circuit by allowing current to flow up to a specific limit and then opening the circuit if that limit is exceeded. That limit is the current rating, expressed in amperes, and it’s the maximum continuous current the fuse is designed to carry before it blows. The rating tells you the safe operating current for the fuse; if the circuit draws more than that, the fuse will heat up and eventually melt its element to interrupt the circuit. The time it takes to blow depends on the fuse type (fast-acting vs slow-blow) and how much the current exceeds the rating, not the rating itself. Voltage rating is a separate specification that indicates the maximum voltage the fuse can safely interrupt, not the current limit. So the rating describes the maximum current the fuse can carry before it opens.