Blue Sea Systems ST Blade Fuse Block, ATO/ATC, 32V DC, Screw Terminal

Overview

The Blue Sea Systems ST Blade is a screw-terminal ATO/ATC fuse block range for organizing DC branch circuit protection on boats and other marine electrical systems. It is built for systems up to 32V DC, with configurations for 6 or 12 circuits, a maximum rating of 100A per block, and up to 30A per circuit when matched with the correct fuse and wire size.

This range helps clean up the common tangle of inline fuses behind helm stations, electronics panels, cabin panels, and accessory distribution areas. A single positive feed supplies the fuse block, then each protected branch circuit leaves from its own screw terminal for items such as electronics, pumps, lighting, instruments, and other low-voltage DC loads.

Versions are available with or without a negative bus and with or without a protective cover, so the layout can match the wiring space on board. Models with a negative bus give DC returns a dedicated landing point at the block, while covered versions add insulation over the live fuse area and include space for circuit labeling.

Key features

• Accepts standard ATO and ATC fast acting blade fuses for common marine DC branch circuits.
• Rated for up to 32V DC, with 100A maximum per block and 30A maximum per circuit when installed with proper wire and fuse sizing.
• Available in 6-circuit and 12-circuit layouts to suit smaller accessory groups or larger helm and house distribution runs.
• Positive distribution bus uses a #10-32 stud, giving the main feed a secure connection point.
• Negative bus versions use a #10-32 stud and help keep positive and negative branch wiring organized in one location.
• Tin-plated copper buses and fuse clips help maintain conductivity in the electrical system.
• Screw terminals accept ring or snap fork terminals, which are common choices for serviceable marine wiring.
• Cover-equipped versions satisfy ABYC and USCG insulation requirements, provide easier fuse access, store two spare fuses, and include label recesses for circuit identification.
• Fuses are sold separately, allowing each branch circuit to be fused to match the connected load and wire size.

Variants

This ST Blade range varies by circuit count, negative bus configuration, and whether a cover is included. The 6-circuit versions suit smaller accessory groups or compact wiring areas, while the 12-circuit versions reduce the need for multiple fuse blocks when more branch circuits are being added.

The negative bus versions are useful when the block will also serve as a local return point for DC loads. Cover-included versions add insulation, spare fuse storage, and label space, while uncovered versions may be selected for installations where a cover is not needed or where the block is being installed inside a protected enclosure.

Installation and setup

The fuse block mounts with #8 screws and uses #8-32 screw terminals with captive star lock washers for branch circuit connections. The screw terminal torque is 18 in-lb, and the main bus stud torque is 24 in-lb. Those torque values matter on boats, where vibration can loosen poorly secured electrical connections over time.

Install it in a dry, serviceable location that allows the cover to open when fitted and leaves enough room to route conductors without sharp bends. Each circuit should be labeled during installation, especially on helm, console, or cabin panels where future troubleshooting needs to be quick and clear.

Electrical use on board

This fuse block works well as a DC sub-panel for electronics and accessory circuits, especially when a main distribution panel is already crowded or when several small loads need nearby protection. It is a practical fit for console rewires, new electronics installs, bilge and utility circuits, lighting additions, and house-side accessory distribution.

Each branch circuit still needs the correct fuse rating for the connected load and wire gauge. For clean service work later, keep the main feed, branch conductors, and negative returns neatly supported, and avoid placing the block where it will be exposed to standing water or constant spray.