BMM603-3SQ Modular Midget Fuse Block: Comprehensive Guide for Industrial Automation Applications

BMM603-3SQ Modular Midget Fuse Block: Comprehensive Guide for Industrial Automation Applications

Historical parts record: Photos and notes below belong to this record. Confirm the offered unit’s full model, condition and available test evidence before ordering.

What is the Bussmann BMM603-3SQ?

The BMM603-3SQ is an Eaton Bussmann TRON modular fuse block for 10 × 38 mm midget fuses, three poles: rated 600 V AC at 30 A, with a 200 kA withstand rating, tin-plated copper terminals for 75/90 °C wiring on AWG 10-18 quick-connect or screw landing, and cULus, CE and UKCA listing. The blocks arrive five to a factory box, assembled in the Dominican Republic (boxes printed MADE IN DOM. REP., file J41 on the newer lot and J33 on the earlier one), with some blocks moulded "Mexico" from another production run — this record merges several intakes of the same part. A few two-pole BMM603-2SQ blocks photographed alongside are a related model, noted where they appear. All 20 photos and 2 videos below are from the same shipments.

3 min readContent reviewed

Part details

BMM603-3SQ, as printed on the block and box
Field Value
Model BMM603-3SQ, EATON Bussmann TRON fuse block
Fuse size 10 × 38 mm midget
Poles 3 (modular, side-clips to add poles)
Rating 600 V AC, 30 A
Withstand 200 kA with the correct midget fuse
Terminals Tin-plated copper, 75/90 °C, AWG 10-18, quick-connect or screw
Approvals cULus Listed, CE, UKCA, RoHS
Assembly origin Assembled in DR (Dominican Republic); some blocks moulded Mexico
Company / file Cooper Bussmann LLC, Ellisville MO 63021; file J33 (earlier) / J41 (later)
Packing 5 blocks per factory box (QTY. 5)
Quantity Multiple boxes across merged intakes
Shipping weight 0.5 kg per block
Scroll sideways to see the full table.

Ratings are read from the moulded print on each block and the box labels in the photo set.

What the modular clip design is for

A midget fuse this small is easy to replace; the hard part is giving it a mounting that survives its own fault clearing. The BMM603 block answers with spring clips that grip the 10 × 38 mm tube at both ends, screw terminals in tin-plated copper behind them, and side clips that let one block latch to the next — build a three-pole feeder today, extend to six poles tomorrow, all on one rail line. The 200 kA withstand figure is the serious half of the rating: with a current-limiting midget fuse in the clips, the block itself is certified to hold through a 200,000-ampere fault without shattering, which is what lets it sit on a 600 V distribution circuit. The two production stamps in this record — Mexican-moulded housings and Dominican-assembled blocks in DOM. REP. boxes — are both normal Bussmann sourcing for the same catalogue part; the ratings print is identical on each. Note when ordering that the related two-pole BMM603-2SQ looks near-identical from the end and takes the same fuse; the pole count and the moulded model number settle it. KOEED lists this block directly — the BMM603-3SQ product page carries the same part.

Photos and video

All images below are original KOEED warehouse photos. Click any photo to view it full size.

Twelve factory boxes laid out
The intake as it arrived: a dozen factory boxes, five blocks each, with one opened block at the left — the scale of this merged record.
BMM603-3SQ block top view
One block from the top: the three fuse pockets with their retaining clips, the moulded H-R-A phase marks, and the modular side wings.
Block side print J33
The side print in full: Bussmann by EATON, BMM603-3SQ Fuseholder, cULus 600V~ 30A, 200kA WITHSTAND 10x38 FUSE, 75/90°C CU, CE and UKCA — file J33 on this earlier batch.
Opened box with bag
A factory box opened: blocks nested inside, accessories bag at the end.
Blocks in box with side print
Blocks stacked in the box, side print visible — BMM603-3SQ, Assembled in DR, AWG 10-18 QUICK CONNECT, 20 A MAX.
Three blocks underside Mexico moulding
The underside of three blocks, each moulded "Mexico" — the second production origin noted in the text.
Three blocks rear terminals
From the terminal side: tin-plated copper strips and the Phillips screw landings, three poles of in and out.
Single block top view
One block alone from above: fuse clips, phase letters, mounting slots and the clip-together wings.
Three blocks standing
Three blocks standing on their terminal rails — the modular silhouette that stacks on a rail line.
Two-pole BMM603-2SQ side print
A two-pole BMM603-2SQ from the same shipment — related model, assembled in DR, file J38. Not the three-pole part this record covers.
Two-pole block end view
The 2SQ's two-pocket end — same fuse size, one pole fewer; included here only to document the shipment.
Three two-pole blocks side by side
Three 2SQ blocks side by side, assemblies marked DR and BR — again the related two-pole model, not the record part.
Single block rear view
A three-pole block from behind: the three tin-plated terminal strips in their housings.
Four boxes open with blocks
Four boxes opened together: side print BMM603-3SQ on every block, the DOM.REP-assembly lot.
Block rear close-up
Terminals at close range: screws, pressure plates and the fuse-clip tails behind each pole.
Four factory boxes J41
Four sealed factory boxes: BMM603-3SQ QTY. 5, TRON Fuse Block, MADE IN DOM. REP., Cooper Bussmann LLC, Ellisville MO — file J41 on this later lot.
Block side print J41
The later-batch side print: same ratings, file J41, AWG 10-18, 20 A MAX, Assembled in DR.
Block rear full view
Rear view of one block: the three pole housings and terminal screws, factory-clean.
Block front bottom view
Closing shot: the fuse pockets and clips from below — the working face of the block.
Second video thumbnail block
One more angle on the fuse pockets and phase mouldings.
Inspection video 1: the blocks as checked at the KOEED warehouse.
Inspection video 2: terminal and clip details.

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