Blue Sea Systems · 7748
See the Blue Sea SafetyHub 150 Fuse Block connection points and wiring example. Open the diagram in Crimp to add your equipment and plan the cables between them.
Open this example as a new project. Use your own parts and cable lengths to make the plan yours.
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.
Wiring diagram
Open this example in Crimp to use your own parts and cable lengths. Review the assumptions and installation notes as you adapt the circuit.
Installation notes
Guidance for this model, with sources linked beside the relevant advice.
Verified against the manufacturer's documentation (rev. 7748 SafetyHub 150 application diagram and current product specifications), checked 2026-10-01. Manufacturer documentation →
The SafetyHub 150 contains four MIDI/AMI fuse positions up to 200 A each and six ATC/ATO positions up to 30 A each, plus a separate negative bus. Blue Sea’s specification does not describe a 150 A block: “150” is the product name. Fuses are purchased separately.
Blue Sea gives 200 A with a 2/0 AWG feeder, 350 A with 4/0, or 600 A with two 4/0 feeds, under its stated 50°C ambient condition. The catalog represents the single-feed 200 A configuration. Adding individual slot ratings is not a valid aggregate rating, and a larger fuse cannot upgrade the feeder arrangement.
Feed the positive input from the protected battery supply. Connect each branch to its correctly sized fuse position, and route returns to the negative bus. The primary studs use M8 hardware; published torques are 20.34 Nm for studs, 3.05 Nm for M5 screws, and 2.03 Nm for 8-32 screws. Identify the fastener before tightening.
The application diagram shows alternatives before or after the battery switch. Bilge pumps and alarms can require independently protected, always-live feeds; other branches can follow the house switch. Verify the desired behavior by switching the system off. The planner labels MIDI and ATC branches separately; one block-wide fuse family would be wrong. Replace the sealed cover and labels after inspecting all connections.
For each protected branch, select the correct cable fuse-type override: MIDI for a MIDI/AMI position or ATC for an ATC/ATO position. Then enter the installed fuse rating. A single block-wide family cannot describe both sections, so the slot label alone must not be treated as proof that the correct fuse type has been selected.
Build it out
Add 7748 to your diagram, then connect your batteries, chargers and loads. Crimp calculates cable sizes and checks the connections as you draw.
Every cable you draw there is sized against ABYC E-11, from the same tables as the reference on this page.
Technical reference
Check the model, ratings and connection points against your own unit before choosing installation hardware.
Check stud sizes, fuse type, run length and how warm the space gets against the gear you actually have before you order.
Catalog connection points, current direction and planning limits. Check the manufacturer's pinout and connector ratings before installation.
BATT +
in
positive · input
NEG BUS
neg-in
negative · bidi
MIDI 1
midi-1
positive · output
MIDI 2
midi-2
positive · output
MIDI 3
midi-3
positive · output
MIDI 4
midi-4
positive · output
ATC 1
atc-1
positive · output
ATC 2
atc-2
positive · output
ATC 3
atc-3
positive · output
ATC 4
atc-4
positive · output
ATC 5
atc-5
positive · output
ATC 6
atc-6
positive · output
RETURNS −
neg-load
negative · bidi
Method & provenance
Manufacturer specifications describe the equipment. Crimp calculates cable results from the circuit and assumptions you enter.
From the maker
Manufacturer, model, ratings and which terminal does what come from the catalog. A newer revision, or the nameplate on the unit in your hand, can say something different — when it does, the nameplate wins.
ABYC E-11
Sized against ABYC E-11 — the US reference, and what Transport Canada accepts as an alternative to TP 1332 for pleasure craft under 24 m. The run length and the current above are what drive the result. Crimp doesn't know how warm your space gets; draw the cable inside an engine-bay zone on the canvas and it sizes for the heat.
Next step
Open this example as a new project. Add your equipment and cable lengths, then review the sizing and checks for your setup.