The Nautilus Firefly Underwater Welding Knife Switch is a professional 400-amp DC welding isolation, monitoring, and control station designed for underwater welding, commercial diving, and other MMA/SMAW welding operations. Positioned between the welding power source and the diver or welding operator, the Firefly provides a convenient surface control point for safely isolating welding current and voltage.

Unlike a basic welding knife switch that only opens or closes the circuit, the Nautilus Firefly incorporates dedicated amp and volt meters. These displays allow the tender or welding supervisor to monitor welding parameters, evaluate the performance of the power source, and identify characteristics of the welding circuit that may affect operating efficiency or weld quality.

A clearly visible indicator light shows when the welding circuit is “hot,” helping the surface team confirm when power is being supplied to the electrode holder. The large, easy-to-operate push/pull switching handle gives the operator positive control over circuit isolation. DIN-style quick-release welding cable connectors are included to simplify connection between the welding machine, Firefly control station, and electrode circuit.

Designed for portable use where a permanent welding station is unavailable, the complete Nautilus Firefly isolation switch is housed in a rugged Peli/iStorm structural-foam utility case. Two front catches and two locking hasps provide added security during storage and transportation. The lightweight, self-contained design weighs approximately 5.5 kg (12.1 lb) and measures 361 x 290 x 165 mm (14.2 x 11.4 x 6.5 inches).

The Firefly is rated for up to 400 amps and 96 volts DC. Its published duty-cycle ratings are 300 amps at 100%, 350 amps at 65%, and 400 amps at 45%. According to Nautilus, the isolation switch meets applicable CE requirements and carries Underwriters Laboratories and Canadian Standards Association approvals.

The Nautilus Firefly is an ideal welding safety switch and monitoring station for underwater wet welding, underwater cutting, marine construction, ship repair, offshore maintenance, commercial diving contractors, and hazardous-area welding applications requiring close control of the welding circuit.

Key Features

• Portable underwater welding knife switch and control station
• Safely isolates welding current and voltage
• Maximum rating of 400 amps and 96 volts DC
• Integrated amperage and voltage meters
• Indicator light shows when the circuit is hot
• Large push/pull isolation handle
• DIN-style quick-release cable connectors included
• Monitors MMA/SMAW welding-machine and circuit performance
• Rugged Peli/iStorm structural-foam carrying case
• Two front catches and two security hasps
• Approximate weight: 5.5 kg (12.1 lb)
• Dimensions: 361 x 290 x 165 mm (14.2 x 11.4 x 6.5 in.)
• Duty cycle: 300A at 100%, 350A at 65%, and 400A at 45%
• Tailor-made configurations available upon request