Mersen Q331145 UltraSafe US143M three-pole DIN rail fuse holder for 14 x 51 mm cylindrical fuse links, rated 50 A with an integrated microswitch and IP20 finger-safe protection.
£76.07
The Mersen Q331145, catalogue number US143M, is a robust three-pole modular fuse holder designed for 14 × 51 mm cylindrical fuse links. Part of the Mersen UltraSafe™ US14 series, it provides dependable overcurrent protection and convenient circuit isolation for industrial machinery, power distribution systems and electrical control panels.
This model includes an integrated microswitch indication system for remote fuse-status monitoring. The auxiliary signalling function allows an operated fuse to be reported to a PLC, alarm circuit or control system, helping maintenance teams locate faults quickly and reduce equipment downtime.
Rated at 50 A, the Q331145 supports applications up to 800 V AC and 1000 V DC under UL ratings, as well as up to 750 V AC or DC under IEC ratings. Its IP20 finger-safe polyamide housing, pressure-plate connections and DIN rail mounting format provide safe, efficient installation in demanding industrial environments.
The Mersen Q331145 securely accommodates three cylindrical fuse links, providing effective protection against overload and short-circuit conditions when fitted with correctly selected fuses. Its three-pole configuration makes it suitable for coordinated protection and isolation within three-phase industrial electrical systems.
The integrated microswitch enables remote fuse-status signalling, allowing maintenance teams or automation systems to identify an operated fuse without relying solely on manual inspection. Combined with its finger-safe construction and high voltage capability, the US143M is well suited to applications where safety, reliability and rapid fault diagnosis are essential.
| Phase | Three Phase |
|---|---|
| Manufacturer | Mersen |
| Series | UltraSafe™ US14 |
| Catalogue number | US143M |
| Manufacturer part number | Q331145 |
| Product type | Modular cylindrical fuse holder |
| Fuse size | 14 × 51 mm |
| Number of poles | 3 |
| Maximum fuse rating | 50 A |
| Conventional thermal current | 50 A |
| Rated voltage AC UL | 800 V |
| Rated voltage DC UL | 1000 V |
| Rated voltage AC IEC | 750 V |
| Rated voltage DC IEC | 750 V |
| Frequency | 50 / 60 Hz |
| Short-circuit current rating | 100 kA |
| Rated insulation voltage | 690 V |
| Rated impulse withstand voltage | 8 kV |
| Indication system | Integrated microswitch |
| Wiring range | #2 to #14 AWG |
| Terminal material | Tin-plated copper |
| Fuse installation method | Clip-in |
| Terminal torque | 3.5 N·m |
| Housing material | Polyamide |
| Protection rating | IP20 |
| Mounting type | DIN rail mounting to EN 60715 |
| Dimensions (H × W × D) | 110.8 × 53 × 76.5 mm |
| Product weight | approximately 0.448 kg |
| EAN / UPC | 0782001310141 |
| RoHS compliance | Compliant |
| HS Code | 85361050 |
| Country of Manufacture | Tunisia |
The Q331145 is a three-pole modular fuse holder used to install 14 × 51 mm cylindrical fuse links in industrial power distribution, machinery and control-panel circuits.
The fuse holder is designed for 14 × 51 mm cylindrical fuse links with a maximum rating of 50 A.
Yes. The US143M incorporates an integrated microswitch that can provide remote fuse-status indication to a monitoring or control system.
The fuse holder is rated up to 800 V AC and 1000 V DC under UL standards, and up to 750 V AC or DC under IEC ratings.
The unit mounts onto a standard DIN rail in accordance with EN 60715, making it suitable for industrial control panels, switchboards and machinery enclosures.
Mersen UltraSafe™ fuse holders are trusted by electrical engineers, OEM machinery manufacturers and panel builders for dependable circuit protection, finger-safe operation and efficient remote fuse monitoring.
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2025 has been a big year for LED Controls, and our blog has expanded accordingly. We've covered a wide range of topics across industrial control and factory automation this year. From core technology explainers and new product releases to panel building best practice...