A blade fuse can match the requested amperage and still be the wrong part for the holder. For purchasing, “mini blade fuse” is too broad: identify the manufacturer's family, complete part number and mating holder before comparing price.
This guide focuses on the physical interface and the evidence needed to approve a fuse-and-holder combination. Use the DC fuse voltage and interrupting-capacity guide for electrical protection requirements and the fuse-holder thermal guide for assembly temperature assessment. Physical fit does not replace either review.
Identify the family before comparing dimensions
The table uses specific Littelfuse examples to show what an RFQ should distinguish. These are reference products, not a SINAWATTS availability list or an interchangeability approval. A family name narrows the search; the offered part's controlled drawing and holder documentation must close it.
On small screens, swipe or scroll sideways to read every column. Keyboard users can focus the table and use the arrow keys.
| Family and reference | Identification focus | Evidence to request |
|---|---|---|
| ATO format: ATOF 287 | Record the actual series; do not shorten every description to “standard blade.” | The offered variant's outline drawing and the holder's accepted fuse specification. ATOF 287 datasheet. |
| MINI 297 | Distinguish this series from a low-profile offer, even when the top width looks similar. | Body and blade dimensions from the exact drawing revision. MINI 297 datasheet. |
| Low Profile MINI 891 | Lower overall height and a specified tuning-fork mating-terminal design are relevant. | The intended terminal system and seating geometry. Low Profile MINI 891 datasheet. |
| MICRO2 327 | “Micro” needs the complete family and part number. | Outline, blade geometry and the holder's approved fuse reference. MICRO2 327 datasheet. |
| MICRO3 337 | This design has three blades and two fuse elements. | The three-terminal interface and circuit schematic, as well as dimensions. MICRO3 datasheet. |
Other manufacturers use their own catalogue terms. Eaton distinguishes ATC, ATM, ATM-LP, ATR and ATL within its blade-fuse range. That terminology is useful for searching, but this guide does not turn those names into a cross-brand substitution table. Request the proposed manufacturer's documented pairing. Eaton blade-fuse overview.
Why matching width does not establish compatibility
The MINI 297 and Low Profile MINI 891 drawings both contain a 10.9 mm width callout. Yet the 891 description specifies lower overall height and mating with tuning-fork terminals. Matching that one width therefore does not establish that the two products engage the same holder correctly. The example is a comparison of published drawing features, not a dimensional acceptance limit. MINI 297 drawing, page 2, Low Profile MINI 891 description and drawing.
Build the dimensional comparison around the interface:
- Body envelope: width, depth, height and clearance under the actual cover.
- Blade geometry: number, spacing, width, thickness and the manufacturer's defined contact region.
- Seating: insertion depth, stop features and contact engagement at the seated position.
- Service access: space to identify, remove and replace the fuse using the specified method.
For each field, record the drawing reference, units, datum and applicable tolerance. A datum is the reference surface or feature from which a dimension is measured. If the catalogue omits a necessary tolerance, request the controlled drawing; do not invent a tolerance around a nominal value. Littelfuse's cited dimensional pages direct users to the outline drawing for dimensions and tolerances.
Quote the complete holder assembly
“Holder included” can hide a bill-of-materials gap. The ATO FH2 datasheet, for example, separately lists housing-only items, housing-and-cover items, a version with blade terminals, and crimp-terminal accessories. It names ATO as the accepted fuse type. Those distinctions make the exact ordering code important; a photograph of an assembled holder does not settle what a quoted line item contains. Littelfuse ATO FH2 datasheet.
Ask for separate identifiers for the fuse, housing, contacts, cover and any supplied leads or seals. Specify whether the quotation covers loose parts or an assembled unit. Request the required wire and termination information where applicable, without assuming that an accessory option is included.
Keep commercial comparison on that same basis. A lower unit price for an empty housing cannot be compared directly with a complete assembly. Ask suppliers to state quantities, packaging, inspection documentation and excluded items; obtain price and lead time for that defined scope.
Use an RFQ decision table
This is a proposed buyer review method, not a manufacturer qualification standard. The responsible engineer should set the applicable acceptance criteria and required tests.
On small screens, swipe or scroll sideways to read every column. Keyboard users can focus the table and use the arrow keys.
| RFQ field | Sufficient reply for review | Hold the decision when |
|---|---|---|
| Fuse identity | Manufacturer, full part number, family and current document revision | Only colour, amperage or a generic family name is supplied |
| Dimensional interface | Controlled fuse and holder drawings, including relevant tolerances and contact engagement | Only overall width or a photograph is offered |
| Holder scope | Housing, contacts, cover and supplied accessories identified by ordering code | The quote and illustrated assembly have different contents |
| Pairing evidence | Holder documentation identifies the accepted fuse specification; exact offered variants are reconciled | The claim is only “it fits” |
| Application review | Separate electrical and thermal requirements are documented for the proposed assembly | Mechanical fit is treated as approval for the circuit |
| First article | Production-representative samples and an agreed inspection plan | Unapproved substitutions appear after sample approval |
Release the combination only after every applicable row is resolved and the responsible engineer accepts the documented pairing and application. An open contact-interface question means the combination remains unapproved, even if purchasing can obtain samples.
Compare three hypothetical supplier replies
Assume a buyer has an existing MINI holder and receives an offer described as a low-profile replacement. The following replies are fictional procurement examples, not SINAWATTS quotations or test results.
Reply A: “Same colour and amperage; compatible.” Hold. Ask for the exact fuse and holder identifiers. Those two observations do not answer the interface questions.
Reply B: “The replacement enters the cavity and the cover closes.” Still hold. Request the controlled drawings and evidence of the intended contact engagement. Cover clearance addresses one field, not the complete mating interface.
Reply C: “Here are the complete part numbers, drawing revisions, holder acceptance document and assembly contents. Contact engagement for this variant is unresolved.” This is a useful, transparent reply, but it still does not justify release. Assign that issue to engineering, obtain the missing evidence and record the decision before accepting the substitution.
This comparison keeps a good documentation package from being mistaken for a completed technical approval.
Make the first article traceable
Link inspected samples to the offered part numbers, lots and drawing revisions. Use the approved, unenergized dimensional inspection method; check markings, seating, cover clearance and the specified contact interface. If insertion or retention testing is required, use the manufacturer's method and the engineer-approved limits. An improvised pull test cannot establish compatibility.
Do not bend blades or modify contacts to make a sample fit. Record discrepancies for disposition, and require re-evaluation when the fuse, contact, holder or relevant drawing changes. The quality-control process provides a place to frame documentation discussions; the RFQ must still define the actual inspection scope.
Buyer FAQ
Does the same fuse colour prove holder compatibility?
No. The cited MINI documentation uses colour to identify amperage. Colour does not identify the complete fuse-and-holder interface or establish application approval.
Can Low Profile MINI replace a standard MINI fuse?
Do not assume so. Compare the exact models, mating contacts and holder documentation. Lower height alone does not answer whether the contact system and engagement are correct.
Can a MICRO3 fuse be treated as a MICRO2 alternative?
No automatic substitution follows from “MICRO.” The cited MICRO3 has three blades and two elements. Its terminal interface and circuit arrangement need their own documented review.
What should a comparable holder quotation include?
Ask for the full assembly contents, exact fuse and holder references, drawings, excluded accessories, quantities and requested inspection records. Have suppliers quote price and lead time against that common scope.
Review the fuse-box product category, then send the existing holder reference, fuse markings, drawings and assembly requirements.