Merit Brass TR4/10R Time Delay Fuse 0.4A 250V RK5

Product Description

The MERIT BRASS TR4/10R is a time-delay fuse rated at 0.4 amps and 250 volts, classified to the RK5 fuse standard. Time-delay fuses in this class are engineered to tolerate brief inrush currents without nuisance tripping while still providing reliable overcurrent and short-circuit protection. The RK5 classification indicates a current-limiting design with defined let-through energy limits, making it suitable for protecting motors, transformers, and sensitive electrical equipment. Electricians and maintenance technicians install fuses of this type in fusible disconnect switches, load centers, and control panels where precise overcurrent protection is required.

This fuse is appropriate for residential and light commercial electrical systems where a low-amperage, time-delay overcurrent device is needed. Typical applications include motor branch circuits, control circuit protection, and panel feeder protection in installations governed by the National Electrical Code. Its 250-volt rating covers standard single-phase branch circuit voltages found throughout commercial and residential service work.

Key Features

• Time-delay design tolerates motor startup inrush currents without nuisance tripping
• RK5 current-limiting classification with defined let-through energy limits
• 0.4-amp current rating for low-amperage branch circuit and control circuit protection
• 250-volt rating suitable for standard single-phase branch circuits
• Compact fuse form factor compatible with standard RK5 fuse holders and disconnects

Compatibility

Designed as an RK5-class time-delay replacement fuse for use in standard RK5-rated fusible disconnect switches, fuse blocks, and load centers accepting 250-volt fuses at or above the 0.4-amp rating.

Installation Notes

Installation must be performed by a qualified electrician in accordance with the National Electrical Code and applicable local codes. Always open and lock out the disconnect or panel before replacing any fuse. Verify that the replacement fuse amperage, voltage rating, and class match the circuit requirements before insertion. Never substitute a higher-amperage fuse to resolve nuisance tripping without first diagnosing the root cause of the overcurrent condition.

Technical Specifications

• Amperage Rating: 0.4 amps
• Voltage Rating: 250 volts
• Fuse Class: RK5
• Fuse Type: Time Delay
• UPC: 78200174754

Standard Information

• Brand: MERIT BRASS
• Manufacturer Part Number: TR4/10R