The M40 Connector: Maximum-Current Industrial Connectivity
When the M23 isn't enough — when you're feeding large motors, generator interconnects, or heavy industrial power distribution — the M40 circular connector takes over. With a 40 mm threaded coupling, M40 delivers per-pin current ratings up to 50 A in a robust IP67-sealed package, making it the connector of choice where threaded lugs and busbars would otherwise be the only option.
Katlax manufactures M40 connectors in 6-pin and 8-pin power configurations at our Santej, Gandhinagar facility. The form factor is significantly larger than M23 (40 mm vs 23 mm thread), but the family inherits the same screw-locking, vibration-immune coupling that defines the entire M-series. M40 is rare across the industry — Katlax is one of the few Indian manufacturers offering it as a standard catalogue item.
M40 Pin Configurations
| Configuration | Typical use case | Notes |
|---|---|---|
| 6-Pin Power | Three-phase motor power + PE + auxiliary lines | Three current-carrying conductors, one protective earth, two auxiliary contacts for brake control or thermal sensors. |
| 8-Pin Power | High-density power distribution; motor power with full feedback | Up to six current-carrying conductors plus PE and auxiliary. Used for compact branch panels and feed runs. |
For exact pinout diagrams and wire-colour conventions, see the Pin Assignment reference. Conductor cross-sections from 4 mm² up to 16 mm² are supported depending on configuration.
Technical Specifications
- Current rating: Up to 50 A per contact (varies by pin configuration and conductor cross-section).
- Voltage rating: 1000 V AC/DC standard for power variants.
- IP rating: IP67 standard when mated; IP68 / IP69K available on request for washdown and submersion applications.
- Mating cycles: 100 minimum per industry standard; field-tested to 500+ in industrial environments.
- Operating temperature: −40 °C to +90 °C standard.
- Housing material: Nickel-plated brass standard; stainless steel for marine and hygienic environments.
- Vibration / shock: Tested to IEC 60068-2-6 and IEC 60068-2-27 — passes industrial vibration profiles without disconnection.
Cable Material Options
Cable jacket selection for high-current M40 applications matters even more than for the smaller M-series — heat dissipation, abrasion resistance, and flex life all factor in:
- PUR (polyurethane): Default for high-current power runs. Excellent oil and abrasion resistance, broad temperature range.
- EPDM rubber: Heavy-duty insulation for harsh outdoor and marine environments.
- Silicone-insulated: Continuous service up to +180 °C for furnace, glass, and metalworking applications.
- PVC: Cost-optimised static-installation use only; not recommended for dynamic applications at M40 current ratings.
Datasheets for every cable jacket option are available on the downloads page.
Applications — Where M40 Replaces Lugs and Busbars
- Large servo and stepper motors: 5 kW and above where M23 current capacity is insufficient.
- Generator and inverter interconnects: Solar inverter output, wind-turbine generator connections, backup-generator panel feeds.
- Heavy industrial machinery: CNC spindle motors, large injection-moulding machine power feeds, press machinery.
- Renewable energy: Solar array string combiners, battery storage system interconnects.
- EV charging infrastructure: High-current charging cable interfaces and station interconnects (where standard CCS connectors aren't used).
- Marine and offshore: Deck-mounted equipment, large pump motors, generator runs on vessels and offshore platforms.
- Mining and earth-moving: Heavy mobile machinery where vibration immunity + IP rating + high current are all required.
How to Select an M40 Connector
- What's the per-pin current? Typical M40 runs are 25–50 A per pin. Below 16 A, M12 L-coded is more economical; above 50 A, busbar or terminal blocks may be preferable.
- How many conductors? Three-phase motor: 6-pin (3L + PE + 2 aux). Single-phase + complex feedback: 8-pin.
- Cable cross-section? 4 mm² (25 A), 6 mm² (32 A), 10 mm² (40 A), 16 mm² (50 A) — derate for ambient temperature and grouping.
- Cable jacket? PUR for dynamic / drag-chain. EPDM for outdoor / marine. Silicone for high-temp. PVC for static only.
- Termination? Pre-molded preferred for IP67/IP68 reliability at high current. Field-attachable available but requires careful torque and seal verification.
- Approvals? CE for EU. UL listing available for North American applications.
Why Katlax for M40
M40 is a low-volume, high-complexity product — most connector manufacturers don't stock it. Katlax produces M40 to order with our standard in-house manufacturing flow: injection moulding, cable processing, over-moulding, and 100% electrical testing. For OEM applications requiring qualified high-current connectors, Katlax M40 is delivered with full test reports, conductor traceability, and ISO 9001:2015 quality documentation.
Certifications: CE, ISO 9001:2015, IPC/WHMA-A-620 for wire harness manufacturing, plus self-declaration on RoHS and REACH. UL listing on specific configurations on request — contact engineering for current cert coverage.
Lead times: M40 is build-to-order — typical 4–6 weeks for sample / small quantities; 8–10 weeks for production runs. For urgent requirements, talk to our engineering team about buffer stock availability on the most common configurations.
Browse, Compare, and Quote
Use the filter sidebar above to narrow the M40 catalogue by pin configuration, gender, or cable specification. For non-standard configurations (custom pin counts, special cable jackets, qualified high-temperature variants), contact our engineering team — quote turnaround under 24 business hours for standard configurations, 3–5 business days for custom designs.