Ferraz Shawmut A6K400R Class RK1 400A 600V Fuse

Product Description

The FERRAZ SHAWMUT A6K400R is a Class RK1 fast-acting blade fuse rated at 400 amps and 600 volts AC (300 volts DC). It belongs to the Amp-Trap product line and is engineered for high-performance overcurrent protection in demanding electrical systems. Class RK1 fuses offer a higher degree of current limitation than standard Class K fuses, making this unit well suited for protecting motors, feeders, and service entrance equipment where tight fault-current control is required. Licensed electricians and industrial maintenance technicians are the primary installers.

This fuse is applied in commercial and industrial electrical panels, motor control centers, switchboards, and distribution equipment where 600-volt-rated overcurrent protection at 400 amps is required. Its fast-acting characteristic makes it appropriate for protecting components sensitive to sustained overloads, including transformers, capacitor banks, and branch circuit conductors. It is also rated for 300 volts DC, covering battery backup systems and DC distribution applications common in facilities with uninterruptible power supplies.

Key Features

• Class RK1 current-limiting performance for tighter fault-current control than standard Class K ratings
• Fast-acting response protects sensitive downstream equipment from sustained overloads
• Dual voltage rating: 600 volts AC and 300 volts DC
• 400-amp continuous current rating for feeder and service entrance applications
• Blade-style form factor for compatibility with standard Class RK1 fuse holders and blocks

Compatibility

Designed as an OEM-style replacement for Class RK1 blade fuse installations rated at 400 amps and 600 volts AC in commercial and industrial overcurrent protection applications.

Installation Notes

Installation must be performed by a licensed electrician in accordance with the National Electrical Code (NEC). De-energize and lock out the circuit completely before removing or installing any fuse. Verify the fuse holder or block is rated for Class RK1 fuses at or above the voltage and amperage of this device before installation. Do not replace a Class RK1 fuse with a lower-rated class, as this reduces current-limiting performance and may not comply with the original equipment design.