Blue Sea Systems ST Glass 6 Circuit Fuse Block with Negative Bus and Cover

The Blue Sea Systems ST Glass 6 Circuit Fuse Block with Negative Bus adds a built-in ground terminal to the standard 5018 block, so all six circuits' returns land in one place alongside their fused positive feeds. It uses the same 3AG glass fuse format — AGC fast-acting or MDL time-delay.

Key features

• 100A total, 30A per circuit, 32V DC maximum
• Integrated negative bus consolidates all six circuit grounds
• Tin-plated copper buses and phosphor bronze fuse clips
• Clear insulating cover with spare-fuse storage and large-format label recesses

This is the block to reach for when wiring several new circuits from scratch and you want a single, tidy termination point for both the fused positive and the negative return — bilge pumps, cabin lights, and small electronics are common candidates. If you're retrofitting into a boat that already has a dedicated ground bus elsewhere, the simpler PN 5018 (no negative bus) saves a little cost.

Because this is a legacy 3AG glass-fuse format, confirm your supplier stocks AGC or MDL fuses in the amperages your circuits need before committing to this block over an ATO/ATC blade-fuse alternative — glass fuses can be less universally available at some marine chandleries than blade fuses. Because it shares the same footprint and #10 screw mounting as PN 5018, you can compare the two side by side and pick based purely on whether you want grounds consolidated here or handled at a separate bus bar. Torque the #10 mounting screws snugly but don't overtighten into the reinforced polycarbonate base, which can crack under excessive force.