Fuse Maintenance & Replacement: Safety and Best Practices

1. Fuse Maintenance

Fuses in service should be regularly inspected. The inspection includes the following items:

• Load current should be compatible with the rated current of the fuse element.

• For fuses equipped with a fuse blown indicator, check whether the indicator has actuated.

• Check the conductors, connection points, and the fuse itself for overheating; ensure connections are tight and making good contact.

• Inspect the fuse exterior for cracks, contamination, or signs of arcing/discharge.

• Listen for any internal discharge sounds within the fuse.

If any abnormalities are found during inspection, they should be corrected promptly to ensure safe and reliable operation of the fuse.

2. Safety Precautions When Replacing Fuse Elements

After a fuse element blows, first identify the cause and rectify the fault before replacement. The cause—short circuit or overload—can be determined by examining the condition of the blown fuse.

• Overload indication:
  Little or no audible sound when blowing; the fuse element melts at only one or two locations. In stepped-section fuses, only the narrow section melts. No charring or burning inside the fuse tube.

• Short circuit indication:
  Loud explosion when blowing; extensive melting or fragmentation of the fuse element; visible charring or burning inside the fuse tube.

Once the cause is identified, locate and eliminate the fault accordingly.

When replacing the fuse element:

• Select a replacement with specifications matching the load characteristics and circuit current.

• Always de-energize the circuit before replacement to prevent electric shock.