Blue Sea Systems
Blue Sea 5025 ST Blade Fuse Block wiring diagram
6-circuit ATC/ATO blade fuse block with integrated negative bus and clear cover. 100 A max per block, 30 A per circuit, 32 V DC max. Accepts ATO/ATC fuses 1–30 A.
Wiring diagram
How the BS 5025 is wired.
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Cable sizing for this example
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Installation notes
Before you install.
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Verified against the manufacturer's documentation (rev. PN 5025 / 5030 wiring diagram; current 5025 specifications), checked 2026-10-01. Manufacturer documentation →
What does the 5025 protect?
The 5025 ST Blade block distributes one positive feed to six individually fused circuits and provides a common negative-return bus. Blue Sea specifies 100 A maximum per block, 30 A per branch and 32 V DC maximum. Six 30 A fuse positions do not make a 180 A panel. Fit the fuse required by each branch's equipment and cable, within the block's limit.
The downloaded wiring diagram covers PN 5025 and 5030. The catalog model here is 5025; check its cover and mounting arrangement against the actual part. The current 5025 product page provides the electrical specifications.
Where do the feed and returns connect?
Connect the protected DC-positive supply to the main positive stud. Each fused output feeds its corresponding load positive. Connect the main negative stud to system negative and the branch returns to the negative screws. Those negative connections are common and are not fused branch outputs.
If the installation has a battery shunt, the negative feed belongs on the system side of it. Keep the positive and negative routing clear when the cover is removed; the drawing's branch numbering is not permission to assume adjacent screws share polarity.
Is an upstream fuse still needed?
Yes. The six blade fuses protect branch circuits, not the supply cable before the block. Blue Sea's diagram calls for suitable main-circuit protection no greater than 125 A, with interrupting capacity appropriate to the source. This is a ceiling, not a universal recommendation for a 125 A fuse. Choose a smaller value when required by the actual feed conductor and installation, and keep operating current within the block's 100 A limit.
What should be checked before use?
Label each branch, verify fuse values, and confirm that the shared positive and negative feeds can carry the combined simultaneous load. Fit and secure the insulating cover. If one circuit fails, check its blade fuse and termination; if several fail together, inspect the common feed, upstream protection and negative return. Do not replace a repeatedly failing fuse with a larger one until the cause and permitted circuit rating are established.
Fit check
Connect it to the rest of your system.
Describe your setup to draft a system with 5025 connected. Review the selected parts and cable lengths, then edit the diagram in Crimp.
The model only picks parts and draws the connections. Every wire size and fuse rating still comes from Crimp's own sizing, never from the model.
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Technical reference
Specifications and terminal map.
Check the model, ratings and connection points against your own unit before choosing installation hardware.
Catalog specification
6-circuit ATC/ATO blade fuse block with integrated negative bus and clear cover. 100 A max per block, 30 A per circuit, 32 V DC max. Accepts ATO/ATC fuses 1–30 A.
Connection limits are listed in the terminal map. Use the manufacturer's documentation for the full specifications.
Terminal map
Catalog connection points, current direction and planning limits. Check the manufacturer's pinout and connector ratings before installation.
IN +
positive · input
IN −
negative · bidi
1
positive · output
2
positive · output
3
positive · output
4
positive · output
5
positive · output
6
positive · output
1
negative · bidi
2
negative · bidi
3
negative · bidi
4
negative · bidi
5
negative · bidi
6
negative · bidi
Sources and sizing method
Equipment specifications. Model details, ratings and terminal roles come from the catalog. Check your unit’s label and current manufacturer documentation for its exact revision.
Example sizing. Wire sizes and fuse ratings apply to the connected example, not a fixed cable size for this component. Set your actual equipment, current, lengths and installation conditions in Crimp before choosing hardware.
Read how the sizing worksNext step
Plan your installation with BS 5025.
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