Standard delivery
£8 ex VAT · free over £200UK parcel delivery is £8 ex VAT, or free on orders over £200 ex VAT.
Heavier items may be charged at a weight-based or pallet rate, shown at checkout.
MERSEN FUSE 600V 400A CLASS J TD FUSE AJT400
Engineered for high-reliability circuit protection, the AJT400 delivers robust performance in demanding industrial environments. This Class J time-delay fuse safeguards equipment with precision, supporting systems up to 600VAC or 500VDC and rated at 400A.
£200.02
Why Choose the Mersen AJT400 Class J Time-Delay Fuse?
The Mersen AJT400 is a premium Class J time-delay fuse engineered to provide dependable overcurrent protection for high-current industrial electrical systems. As part of the trusted Mersen Amp-Trap 2000® AJT series, it combines exceptional current-limiting performance with time-delay characteristics, making it ideal for protecting main circuits, feeders, motor branch circuits and industrial machinery exposed to demanding operating conditions.
Built using advanced fuse technology, the AJT400 is designed to tolerate temporary motor starting and transformer energisation currents while rapidly clearing sustained overloads and short circuits. Its compact Class J construction requires approximately half the mounting space of comparable Class RK fuses, allowing more efficient panel layouts while maintaining high levels of electrical protection.
With a rated current of 400 A and a 600 V AC / 400 V DC rating, the AJT400 is ideally suited to industrial power distribution systems, OEM machinery, switchboards and motor control applications. The blade terminal design provides secure installation into compatible Class J fuse holders and fused disconnect switches.
Key Advantages
- High-capacity Class J time-delay fuse for industrial circuit protection.
- 400 A current rating for demanding power distribution applications.
- 600 V AC and 400 V DC voltage rating.
- Time-delay characteristics accommodate motor and transformer inrush currents.
- Superior current-limiting performance helps minimise equipment damage.
- Compact Class J design saves valuable control-panel space.
Key Features
- Mersen Amp-Trap 2000® AJT series.
- 400 A rated current.
- 600 V AC / 400 V DC rated voltage.
- Class J time-delay fuse construction.
- Blade terminal connection.
- 200 kA AC interrupting rating.
- Available with SmartSpot® visual open-fuse indication.
- Supports IEC Type 2 No Damage protection.
Reliable Protection for High-Current Industrial Systems
The Mersen AJT400 protects electrical equipment by interrupting dangerous overload and short-circuit currents before they can damage motors, transformers, switchgear and power distribution equipment. Its time-delay operation allows temporary inrush currents during normal equipment start-up while maintaining dependable protection against sustained faults.
Its high interrupting capacity and advanced current-limiting characteristics help reduce thermal and mechanical stress on downstream equipment, making it an excellent choice for industrial facilities where reliability, uptime and equipment protection are essential.
Typical Applications
- Main and feeder circuit protection.
- High-current motor branch circuits.
- Industrial transformer protection.
- Switchboards and power distribution panels.
- OEM machinery and automation systems.
- Industrial fused disconnect switches.
Technical Specifications
Tick the specs you need, then view products that match.
| Current | 400 A | |
|---|---|---|
| Voltage | 600 V | |
| Fuse Type | UL class | |
| Fuse Class | Time delay | |
| Item number | AJT400/600 | |
| Description | Reducer Fuse AJT - Class J - Time-delay 600VAC 500VDC 400A Blade | |
| EAN/UPC Code | 782001463915 | |
| Rated voltage AC UL | 600 V | |
| Rated voltage DC UL | 500 V | |
| Frequency (Hz) | 50/60 Hz | |
| Ampere Rating | 400 A | |
| AC or DC | AC/DC | |
| Fuse Class | Class J | |
| Speed/Characteristic | Time Delay | |
| Mounting | Clip or Bolted | |
| AC Max I.R./Breaking Capacity | I1: 200 kA | |
| Connection/Terminal Material | Brass | |
| Connection/Terminal Type | Blade | |
| Product Diameter | 63.5 mm | |
| Product Length | 203.2 mm | |
| Sell Pack Quantity | 1 EA | |
| Sell Pack Weight | 1.5467 kg | |
| Sell Pack Width | 63.5 mm | |
| Sell Pack Length | 222.2 mm | |
| Sell Pack Height | 60.5 mm | |
| Product group | Low Voltage UL/CSA Fuses | |
| Body/Insulating Material | GMG | |
| Product Weight | 1.4742 kg | |
| HS Code | 85361090 | |
| Country of Manufacture | Mexico |
Frequently Asked Questions
What is the Mersen AJT400 used for?
The AJT400 protects high-current industrial main, feeder and branch circuits against overloads and short-circuit faults.
What is the current rating of the AJT400?
The fuse has a rated current of 400 A.
What voltage is the AJT400 rated for?
The AJT400 is rated for operation at up to 600 V AC and 400 V DC.
Can the AJT400 withstand motor starting currents?
Yes. Its time-delay characteristics allow temporary motor starting and transformer inrush currents while maintaining reliable protection against sustained overloads and faults.
Where is the Mersen AJT400 typically installed?
It is commonly installed in industrial switchboards, machinery, motor control centres and power distribution equipment using compatible Class J fuse holders or fused disconnect switches.
Trusted for Industrial Circuit Protection
Mersen Amp-Trap 2000® AJT Class J fuses are trusted by electrical engineers, panel builders and OEM manufacturers worldwide for dependable overcurrent protection, excellent current limitation and long-term industrial reliability.
