Proper Fit of Replacement Fuses

When you have obtained a proper replacement fuse, you must make certain it will fit correctly in the fuseholder. If the fuseholder is corroded, the fuse will not fit properly. In addition, the corrosion can cause increased resistance or heating. Clean corroded terminals with fine sandpaper so that all corrosion is removed. Do NOT lubricate the terminals. If the terminals are badly pitted, replace the fuseholder. Be certain the replacement fuseholder is the correct size and type by checking the parts list in the technical manual for the equipment.

After you check for and correct any corrosion problems, be certain the fuse fits tightly in the fuseholder. When you insert the fuse in the cap of a plug-type fuseholder, the fuse should fit tightly. A small amount of pressure should be needed to insert the fuse and cap into the fuseholder body.

In clip-type fuseholders, the clips can be easily bent out of shape. This causes an incorrect fit, which in time could cause an equipment malfunction. Figure 14 shows examples of correct and incorrect fuse contacts for clip-type fuseholders used with knife blade and ferrule cartridge fuses. The clips shown in the left picture of each row have the correct contact. The three pictures on the right of each row show incorrect contact. Notice how the clips are not contacting completely with the knife blade or ferrules. This incomplete contact can. cause corrosion at the contacts, which in turn can create a high resistance and drop some of the circuit voltage at this point.