Blue Sea Systems
Blue Sea MaxiBus 250A 2126 wiring diagram
250A common bus, six 5/16"-18 studs.
Wiring diagram
How the MaxiBus 250 is wired.
Open this example in Crimp to use your own parts and cable lengths. Review the assumptions and installation notes as you adapt the circuit.
Cable sizing for this example
Use the diagram as a starting point for your installation. Replace the example equipment and cable lengths with your own, and check the connections against your exact model's instructions.
Cable sizes depend on the connected equipment, current and cable lengths. Add those details in Crimp to size each run.
Installation notes
Before you install.
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Verified against the manufacturer's documentation (rev. 2126 customer drawing rev 3, 2023-04-13; current product specifications), checked 2026-10-01. Manufacturer documentation →
Which MaxiBus is this?
The Blue Sea 2126 is a single common rail with six 5/16-inch-18 studs, rated 250 A continuous and 48 V DC maximum. The downloaded customer drawing identifies the exact part and its M5/#10 mounting clearances. Its manufacturer product specifications supply the electrical rating and torque.
How are the six posts used?
Every stud is electrically common. The canvas defaults to a negative-return bus; none of its posts is isolated from the others. With a battery monitor, place this system negative rail after the shunt so load and charging returns are measured. Do not put a positive cable on the same rail.
The 250 A rating applies to the bus assembly, not six independent 250 A outputs. Check how aggregate return current moves between the battery/shunt connection and the attached equipment. A nominal 48 V system may charge above the bar's 48 V DC maximum, so verify actual operating voltage if using it on a positive rail elsewhere.
Which hardware and protection are needed?
The drawing specifies 5/16-inch or M8 ring terminals on the stainless studs and serrated flange nuts. The product page gives 132 in-lb / 14.91 N·m stud torque. The bar's mounting hardware is separate from its electrical fasteners; leave clearance for cable bends and support the conductors.
The optional 2718 insulating cover fits this model. A cover does not make the rail waterproof or supply fault protection. Fuses belong in the appropriate source and branch circuits; a busbar cannot interrupt an overloaded conductor.
What should be checked during commissioning?
Verify that every return is on the intended side of the shunt, connections are clean and firmly seated, and no unintended chassis path bypasses monitoring. Compare loaded voltage drop across suspect joints when diagnosing heating or missing current. Do not solve a hot joint by exceeding the specified torque.
Fit check
Connect it to the rest of your system.
Describe your setup to draft a system with 2126 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
250A common bus, six 5/16"-18 studs.
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.
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negative · bidi
4
negative · bidi
5
negative · bidi
1
negative · bidi
2
negative · bidi
3
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 MaxiBus 250.
Open this example as a new project, or add this component to your existing diagram. Use your equipment and cable lengths to review the sizing.
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