Weidmueller BFSC busbar/DIN-rail screw accessory screw size
M4 / M5 · 8 to 9 mm long
The screws used on Weidmueller BFSC busbar/DIN-rail screw accessory are M4 and M5 in lengths from 8 to 9 mm.
There are 2 separate fitment records for it, including catalog lists 'BFSC M4X9T' and 'BFSC M4X30' screw variants for busbar/enclosure rail mount (M4) and catalog lists 'BFSC M5X8 SCHLITZ' slotted screw variant for busbar/rail fastening in enclo (M5).
Head and drive, as the sources state them: Slotted drive.
2 of the 2 records are marked confirmed, drawn from 1 source (assets.dam.weidmueller.com).
For reference, M4 is 4 mm across the threads at 0.7 mm pitch. The imperial size people confuse it with: #8-32 (4.17 mm) — the standard US PC/rack screw, close but not the same.
Weidmueller BFSC busbar/DIN-rail screw accessory screw specifications
One row per fitment record. Head, drive are shown only where the source states them; pitch is the ISO coarse pitch for the thread.
| Thread | Length | Pitch | Head | Drive | Where it goes | Status |
|---|---|---|---|---|---|---|
| M4 | 9 mm | 0.7 mm | not stated | not stated | Catalog lists 'BFSC M4X9T' and 'BFSC M4X30' screw variants for busbar/enclosure rail mounting | Confirmed |
| M5 | 8 mm | 0.8 mm | not stated | Slotted | Catalog lists 'BFSC M5X8 SCHLITZ' slotted screw variant for busbar/rail fastening in enclosures | Confirmed |
Fitment records and sources
Catalog lists 'BFSC M4X9T' and 'BFSC M4X30' screw variants for busbar/enclosure rail mounting
pitch 0.7 mm · tap 3.3 mm · clearance 4.5 mm · PH2 / Torx T20
Catalog lists 'BFSC M5X8 SCHLITZ' slotted screw variant for busbar/rail fastening in enclosures
pitch 0.8 mm · tap 4.2 mm · clearance 5.5 mm · PH2 / Torx T25
How to check the screw before you buy
- Board standoffs and enclosure bosses set the usable length: the screw should clamp the board without bottoming in the standoff.
- Diameter: across the threads an M4 screw measures about 4 mm with calipers (usually a hair under). This device also uses M5, so measure each screw rather than assuming they match.
- Pitch: 0.7 mm from one thread crest to the next (14.29 crests per centimetre). A thread pitch gauge or the pitch-gauge tool settles it in seconds.
- Length: measure from under the head to the tip for pan, button, wafer and cap heads; countersunk (flat) heads are measured overall.
- The records span 8–9 mm, which means different positions take different lengths — match each hole to its own screw.
- Driver: the source names a Slotted drive. For comparison, standard M4 heads take PH2 (Phillips) or T20 (Torx), or a 3 mm hex key.
- Tightening: no device-specific torque is published in these records. The site's general figure for M4 is about 2.0-3.0 N·m into metal threads and 0.8-1.4 N·m into plastic bosses; snug it up and stop.
Common mix-ups with M4 / M5
- Grounding/earth-stud screws on hazardous-area (ATEX/IECEx) gas detectors are commonly M4 even though the enclosure body uses larger threaded glands — don't extrapolate the earth screw size to the whole unit.
- There is no single standard Picatinny/rail screw size; makers use metric M3/M4 and imperial 6-48 or 8-40 interchangeably. Always measure the existing screw.
- Commercial washer-extractor cabinets mix DIN 933 (hex head, full thread) and DIN 84A (slotted pan/cheese head) M5 screws for different panels on the same machine line, so a single family/brand isn't consistent across all fasteners.
- M5x0.8 is the de facto universal bike thread — confirm 0.8mm pitch before threading into carbon or alloy bosses.
More in Electronics, Racks & Enclosures
The same screw also fits
Devices whose records share a thread with Weidmueller BFSC busbar/DIN-rail screw accessory, closest length match first.
- Electrolux Professional compact rack-type dishwasher also M5 × 8 mm
- DIN rail clips and enclosure brackets also M4 × 9 mm
- cab Applicator A3200 print-and-apply labeling system (packaging line hardware) also M4 × 9 mm
- Marine-grade set/grub screw (DIN 916, A4 stainless) also M5 × 8 mm
- DIN 41612 backplane / rack card retention also M4 × 9 mm
- Crowcon Xgard Bright fixed gas detector (mining/oil & gas field electronics) also M4 × 9 mm
- Marine electronics housings also M4 × 9 mm
- Soundbar wall brackets also M4 × 9 mm
Questions about Weidmueller BFSC busbar/DIN-rail screw accessory screws
- What size screw does Weidmueller BFSC busbar/DIN-rail screw accessory use?
- M4 × 9 mm for catalog lists 'BFSC M4X9T' and 'BFSC M4X30' screw variants for busbar/enclosure rail mounting; M5 × 8 mm for catalog lists 'BFSC M5X8 SCHLITZ' slotted screw variant for busbar/rail fastening in enclosures.
- How long are the screws in Weidmueller BFSC busbar/DIN-rail screw accessory?
- The records range from 8 to 9 mm depending on the position, so match each screw to its own hole.
- What is the thread pitch of an M4 screw?
- 0.7 mm (coarse), which is the standard pitch for M4 machine screws; a 0.5 mm fine pitch exists but is uncommon. The tap drill is 3.3 mm and the normal clearance hole is 4.5 mm.
- What screwdriver do I need for Weidmueller BFSC busbar/DIN-rail screw accessory?
- The source lists a Slotted drive. Standard M4 heads otherwise take PH2 (Phillips) or T20 (Torx), or a 3 mm hex key.
- Can I use an imperial screw instead of M4?
- No. Imperial look-alike: #8-32 (4.17 mm) — the standard US PC/rack screw, close but not the same. Use a true M4 screw so it does not cross-thread or strip the hole.