Call Us Today
01706 242050
Trade Portal
MERSEN FUSE US143I US143I

MERSEN FUSE US143I US143I

Mersen P331144 UltraSafe US143I modular fuse holder for 14×51 mm cylindrical fuse links with 3-pole configuration, visual blown fuse indicator, 50 A rating and IP20 finger-safe protection.

SKU: P331144Alt SKU: US143IMPN: P331144
Price
List Price £89.27 ex VAT
Your Price (ex VAT)
£89.27
Manufacturer Lead Time Please contact us for a delivery time before you order
Get the best trade prices Trade exclusive

Create a trade account to unlock exclusive pricing, special offers and more.

Sign up for a trade account Quick & easy setup
SUBTOTAL (EX VAT) £89.27
Trade pricing is personalised to your account

Manufacturer Lead Time

Sold in packs of 2

£89.27

Why Choose the Mersen P331144 UltraSafe™ US143I Fuse Holder?

The Mersen P331144, catalogue reference US143I, is a premium UltraSafe™ modular fuse holder designed for 14×51 mm cylindrical fuse links. Its 3-pole configuration and integrated visual blown fuse indicator provide dependable overcurrent protection whilst enabling rapid local identification of an operated fuse in industrial electrical systems.

Part of the trusted Mersen UltraSafe™ US14 series, the US143I features a robust thermoplastic construction with IP20 finger-safe protection, including during fuse replacement. The modular design allows quick DIN rail installation and can be field assembled with compatible accessories to create multi-pole arrangements where required.

Rated at 50 A with voltage ratings up to 800 V AC UL, 750 V AC IEC and 1000 V DC UL, the P331144 is ideal for industrial control panels, OEM machinery, motor control centres and electrical distribution equipment requiring reliable circuit protection and clear fuse indication.

Key Advantages

  • Designed for 14×51 mm cylindrical fuse links.
  • 3-pole modular construction.
  • Integrated visual blown fuse indicator.
  • 50 A current rating.
  • Rated up to 800 V AC UL, 750 V AC IEC and 1000 V DC UL.
  • Finger-safe IP20 protection.
  • Pressure-plate terminals provide secure conductor retention.
  • DIN rail mounting for straightforward installation.
  • Compatible with field assembly pin-tie kits.

Key Features

  • Mersen UltraSafe™ US14 series.
  • Catalogue number US143I.
  • Manufacturer part number P331144.
  • Suitable for 14×51 mm cylindrical fuse links.
  • 3-pole configuration.
  • Integrated visual blown fuse indicator.
  • 50 A conventional free-air thermal current.
  • 800 V AC UL / 750 V AC IEC / 1000 V DC UL ratings.
  • Pressure-plate terminals.
  • IP20 finger-safe enclosure.
  • DIN rail mounting.
  • Compatible with optional auxiliary microswitch accessories.

Reliable Industrial Circuit Protection

The Mersen P331144 combines dependable overcurrent protection with an integrated visual indication system that enables maintenance personnel to quickly identify an operated fuse without removing the fuse holder. This helps reduce downtime and simplifies troubleshooting in industrial installations.

Its UltraSafe™ finger-safe construction, compact modular format and robust pressure-plate terminals make it an excellent solution for machinery, automation systems and electrical distribution equipment where reliability and safety are essential. Optional auxiliary microswitches are available separately for applications requiring remote fuse-status indication.

Typical Applications

  • Industrial control panels.
  • Motor control centres.
  • OEM machinery.
  • Industrial automation systems.
  • Power distribution equipment.
  • Process control installations.
  • Renewable energy systems.

Technical Specifications

Phase Three Phase
Manufacturer Mersen
Series UltraSafe™ US14
Model US143I
Manufacturer part number P331144
EAN / UPC 0782001311131
Product type Modular fuse holder
Fuse size 14 × 51 mm cylindrical fuse links
Number of poles 3
Rated current 50 A
Rated voltage AC (UL) 800 V
Rated voltage AC (IEC) 750 V
Rated voltage DC (UL) 1000 V
Frequency 50 / 60 Hz
Fuse indication Visual blown fuse indicator
Terminal type Pressure plate
Protection rating IP20
Mounting type DIN rail mounting
Approximate weight 0.44 kg
HS Code 85361050
Country of Manufacture Tunisia
Poles 3-pole
Device Type Fuse base / holder
Fuse Size 14x51 mm
Current 50 A
Voltage 800 V

Frequently Asked Questions

What is the Mersen P331144 used for?

The P331144 is a three-pole modular fuse holder designed to protect industrial AC and DC electrical circuits using 14×51 mm cylindrical fuse links.

Which fuse size is compatible with the P331144?

It is designed specifically for 14×51 mm cylindrical fuse links.

Does the P331144 include a blown fuse indicator?

Yes. It incorporates an integrated visual blown fuse indicator for rapid local identification of an operated fuse.

Can remote fuse indication be added?

Yes. The UltraSafe™ US14 range supports compatible auxiliary microswitch accessories that can be fitted separately where remote fuse-status signalling is required.

What are the electrical ratings?

The P331144 is rated for 50 A and supports systems up to 800 V AC UL, 750 V AC IEC and 1000 V DC UL.

Trusted by Electrical Professionals Worldwide

Mersen UltraSafe™ fuse holders are trusted by panel builders, OEMs and industrial engineers for delivering dependable circuit protection, finger-safe operation and reliable performance across demanding industrial installations.

● Service Agreements

Credit Accounts

Our service agreements are built to support long term procurement relationships. By working closely with engineering teams and procurement departments, we help streamline purchasing processes while ensuring consistent access to critical components and sourcing support when it matters most.

 Priority sourcing and supply support

 Flexible payment terms for qualifying organisations

 Support for engineering, maintenance, and operations

500 +

Stock lines ready to ship

1,000 +

Same day dispatches

3500 +

Customers supported

28 

Trusted Manfacturers

● frequently asked questions

Common questions about our products and support

 

At Led Controls Ltd we help engineers source the right automation and control gear with confidence. below are quick answers to what we are asked most often.

What product ranges do you supply

We supply all leading manfacturers in our industry. we offer next day delivery on most poplour products. 

Can you help specify the correct part?

Your content goes here. Edit or remove this text inline or in the module Content settings. You can also style every aspect of this content in the module Design settings and even apply custom CSS to this text in the module Advanced settings.

Do you have stock for urgent orders?

Your content goes here. Edit or remove this text inline or in the module Content settings. You can also style every aspect of this content in the module Design settings and even apply custom CSS to this text in the module Advanced settings.

What are your delivery times and costs?

Your content goes here. Edit or remove this text inline or in the module Content settings. You can also style every aspect of this content in the module Design settings and even apply custom CSS to this text in the module Advanced settings.

What about warranties, returns and faulty items?

Your content goes here. Edit or remove this text inline or in the module Content settings. You can also style every aspect of this content in the module Design settings and even apply custom CSS to this text in the module Advanced settings.

● latest blog

Discover  our latest insights and
expert advice

From a Simple Idea to Small Business of the Year: The LED Controls Story So Far…

From a Simple Idea to Small Business of the Year: The LED Controls Story So Far…

by | Aug 11, 2026 |

LED Controls is a specialist distributor of factory automation and industrial controls, supplying OEMs, machine builders, panel builders and end users throughout the UK and worldwide. As a trusted UK distributor for many of the world’s leading automation manufacturers, we provide industrial control products, technical expertise and bespoke automation solutions backed by outstanding customer service.

LED Controls: Danfoss Drives Authorised Partner

LED Controls: Danfoss Drives Authorised Partner

by | Jan 17, 2026 |

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...

LED Controls: Your Complete Control Panel Solution

LED Controls: Your Complete Control Panel Solution

by | Jan 17, 2026 |

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...