Overview

The Blue Sea Systems A3T / Class T Fuse is a fast acting DC fuse range for high-amperage marine battery and inverter circuits where fault current can be severe. These Class T fuses are rated up to 125V DC with a 20,000A interrupt capacity at 125V DC, giving the circuit protection needed around large battery banks, including lithium-ion and TPPL installations.

This fuse range is used with Blue Sea Systems Class T fuse blocks and covers amperage options from 110A to 400A. It is a practical fit for boats with inverter systems, charging equipment, high-output DC distribution, and other battery-fed loads that need short-circuit protection close to the power source.

Key features

• Class T fuse format for high-amperage DC circuit protection on marine electrical systems.
• 125V DC maximum voltage rating for use in DC battery and inverter circuits.
• 20,000A interrupt capacity at 125V DC for large battery banks with high available fault current.
• Fast short-circuit response suited to inverter feeds and other high-current electronics.
• Amperage range from 110A to 400A to match different cable sizes, loads, and fuse block configurations.
• Works with Blue Sea Systems Class T fuse blocks, with lower and higher amperage ranges using the matching block size.
• Commonly used for battery banks that include lithium-ion or TPPL batteries, where high interrupt capacity matters.

Variants

This product family varies by amperage rating. Available configurations include 110A, 125A, 150A, 175A, 200A, 225A, 250A, 300A, 350A, and 400A, allowing the fuse to be matched to the protected circuit rather than treated as a one-size part.

The 110A through 200A options are associated with the Blue Sea Systems Class T fuse block range for 110A to 200A fuses, while the 225A through 400A options are associated with the higher-amperage Class T fuse block range. Confirm the required amperage against the vessel wiring, equipment manual, and fuse block before installation.

Installation and setup

Install this fuse in the correct Class T fuse block and place it as close to the battery or power source as the vessel layout and applicable standards allow. The fuse rating should be selected based on the protected cable, connected equipment, and the system design, not only on the maximum current draw of the load.

In inverter and charger installations, this style of fuse is often installed on the main positive feed between the battery bank and the equipment. Use properly sized lugs, clean contact surfaces, and the specified fuse block so the connection remains secure under vibration and normal boat movement.

Compatibility and fit

This range is intended for DC systems that require Class T fuse protection up to 125V DC. It is most relevant on larger 12V, 24V, and higher-voltage DC battery systems where the battery bank can deliver high short-circuit current and a standard low-interrupt fuse may not be suitable.

Boat owners, installers, and refit teams use these fuses when building or servicing inverter circuits, house battery banks, and high-current DC distribution. The correct choice depends on the electrical design of the boat, the amperage rating required, and the matching Class T fuse block.

What’s included

• One Blue Sea Systems A3T / Class T fuse