Best Fuse Storage and Handling Tips

About this list

A current-limiting fuse is a precision part: fine silver or copper elements held in compacted filler inside a sealed body. Most of what can go wrong with one before it enters service is mechanical or environmental. The tips below come from ABB's published handling guidance for medium voltage fuse-links, Mersen's 2024 catalog, the fuse items in the ANSI/NETA acceptance testing specification and the IEC 60282-1 replacement practice that ABB cites.

Where we quote a storage limit, it is the manufacturer's figure for its own products. Always check the fuse manufacturer's own instructions for the part you hold.

1. Keep fuses in their original packaging until installation

In short: Stores, trucks and job-site laydown areas

ABB's guidance is direct: fuses should always be transported in their packaging. Fuse-links are usually packed individually in cartons and then collectively in larger boxes. The carton protects the body and end caps, keeps the nameplate legible and keeps the part number with the fuse.

Unpack at the point of installation, not at the receiving dock, and keep the carton until the fuse is in its clips.

2. Store dry, within the manufacturer's temperature and humidity limits

In short: Warehouses, substations and unconditioned spares rooms

ABB specifies that its fuse-links be stored in a dry place, at temperatures from -25 °C to 50 °C and relative humidity not exceeding 85 percent. Other manufacturers may publish different figures, so check the instructions for the fuses you hold.

In hot, humid climates such as South Florida, check an unconditioned container or shed against those limits before using it as a fuse store. A climate-controlled store room is the simple answer.

3. Keep the store air free of dust, corrosive gases and salt

In short: Coastal sites, chemical plants and dusty industrial yards

ABB adds that the surrounding air must not be significantly contaminated by dust, smoke, corrosive or flammable gases, or salt vapors. Contamination on ferrules and end caps can add contact resistance, and heat, once the fuse is in service.

For coastal utilities and plants near the sea, that means keeping fuses sealed in their cartons and away from doors that open to salt air.

4. Protect fuses from shocks in transport and handling

In short: Moving stock between stores, service trucks and sites

ABB says that when transporting fuses, attention must be paid to the information signs on the packaging and that the cargo must be protected against shocks and humidity. Secure cartons so they can't slide or fall, and carry fuses by hand rather than throwing or dropping them.

A fuse that has taken a hard knock may look fine from the outside. That is why the receiving and pre-installation checks below matter.

5. Inspect every fuse on receipt and again before installation

In short: Receiving inspection and the crew about to install

ABB's pre-installation checklist starts with two physical checks: the fuse-link is not damaged, and there is no sand inside the fuse packaging. Loose filler in the box means the body or seal has been compromised, and that fuse should not go into service.

Next, check that the nameplate data and the dimensions match the circuit documentation or the fuse being replaced. The ANSI/NETA acceptance testing specification makes the same comparison: nameplate data against drawings, and fuse sizes and types against the drawings and the coordination study.

6. Check resistance before the fuse goes into service

In short: Critical circuits and fuses from long-term spares stock

ABB's checklist also asks that the measured resistance of the fuse-link match ABB's catalog data or the documentation supplied with the fuse, measured with a milliohmmeter at about 20 °C. This catches element damage that a visual check will miss.

Our article on testing high voltage fuses covers resistance measurement, set comparison and the safety steps around it.

7. Keep indoor-only fuses indoors

In short: Mixed indoor and outdoor spares stock

Many medium voltage fuses are built for indoor use or use inside an enclosure only; Mersen marks many of its series "Suitable for use indoors or in an enclosure only". ABB explains that outdoor-rated fuses rely on sealing to keep protecting in high humidity or condensation.

Label shelves by environment, so an indoor fuse doesn't end up in an outdoor fuse mount because it happened to fit the clips.

8. Install with the circuit de-energized and the contacts clean

In short: The last handling step before service

ABB recommends replacing fuse-links with the circuit voltage-free. Follow the site's NFPA 70E program and lockout/tagout, and leave the work to qualified persons. ABB's list for the installation itself: fuse base contacts and connections in good condition and protected with acid-free vaseline, insulators free from dirt, the fuse seated correctly in the base contacts, and the striker directed toward the tripping or signaling device.

The ANSI/NETA acceptance testing specification adds verifying that each fuse has adequate mechanical support and contact integrity.

9. Keep sets matched and quarantine fuses from a faulted circuit

In short: Spares management after a fault

ABB, citing IEC 60282-1, recommends replacing all three fuse-links in a three-phase circuit even if only one or two blew, unless it is certain that no fault current passed through the others, because that current may significantly affect a fuse-link's characteristics. Fuses removed from a faulted circuit should be scrapped or set aside for investigation, not returned to the shelf.

ABB also recommends against mixing fuse-link types in one three-phase set, meaning different classes or different manufacturers, even with the same rating plate data. Stock and issue fuses as matched sets.

10. Plan spares around lead time and keep part numbers on record

In short: Maintenance planners and storeroom managers

Keep a record of every installed fuse by manufacturer part number, rating class, voltage and current rating, with the circuit it protects. When a fuse operates, the record tells you what to issue, and it makes a cross-reference possible if the original part is hard to get.

DENCO quotes a 30-day lead time on all products; lead times across the industry are commonly longer. If you send the part number of an installed fuse, DENCO engineering will confirm an equivalent. DENCO's published cross-references include GE 9F60 series to DENCO E-rated Type EJ-1.

See the DENCO range

A receiving checklist for medium voltage fuses

A short checklist for the storeroom, based on the sources above:

• Carton intact, package markings observed, no loose sand in the box.
• Nameplate: manufacturer, part number, class, voltage rating and current rating match the order and the circuit record.
• Environment: indoor-only or outdoor-rated, as the destination requires.
• Resistance recorded at a known ambient temperature, where your procedure calls for it.
• Stored dry, in clean air, within the manufacturer's temperature and humidity limits.
• Issued as a matched set, never mixed with fuses of another class or manufacturer.

About DENCO

DENCO Fuses, Inc. in Miami, Florida, has over 100 years of combined experience solely in manufacturing electrical fuses and serves utilities, OEM and specialty custom design customers, electrical contractors and transit. Fuses are tested in-house at DENCO's factory lab, and third-party testing at IPH Berlin is available on client request. For storage or handling questions about a specific DENCO part, contact DENCO engineering.

Frequently asked questions