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1.3.1 Circuit Breakers

Overview

AUX-side circuit breakers split into two banks:

  1. Battery-side bank (3 CBs at AUX battery+ in passenger rear wheel well, within 7" per code)
  2. Firewall-side bank (2 CBs at Firewall CONSTANT Bus in cabin)

All Mechanical Products Series 17 (except audio amp on Blue Sea 187).

Battery-Side CBs (Passenger Rear Wheel Well)

Mounted inline on a bracket within 7" of AUX battery+ terminal. Protect the three protected feeds leaving the battery.

Circuit Model Rating Reset Type Power Path Max Load Sizing
Forward Feed (to Firewall Bus) Mechanical Products
(174-S2-300-2)		 300A Manual AUX battery+
└→ 300A CB
   └→ Firewall CONSTANT Bus		 ~152A combined max (SP + BODY PDU) 197% of combined load (Fusion relocated to direct AUX feed)
SafetyHub 150 (Recovery) Mechanical Products
(174-S2-150-2)		 150A Manual AUX battery+
└→ 150A CB
   └→ SafetyHub 150		 ~100A (ARB 90A + Winch Trigger 10A) 150% of max load (future-proofed)
JL Audio MV800/8i Amp Blue Sea
(187-100A)		 100A Manual AUX battery+
└→ 100A CB
   └→ JL Audio MV800/8i (under rear seat)		 80A max (fuse-limited) 125% of fuse rating — wire protection (4 AWG short run); amp's 80A internal fuse is primary trip path

Firewall-Side CBs (Co-located with Firewall CONSTANT Bus)

Mounted within 7" of Firewall CONSTANT Bus. Protect each downstream controller.

Circuit Model Rating Reset Type Power Path Max Load Sizing
SwitchPros RCR-Force 12 Mechanical Products
(174-S2-150-2)		 150A Manual Firewall CONSTANT Bus
└→ 150A CB
   └→ SwitchPros		 ~100A (all lighting outputs on) 150% of max load
BODY PDU Mechanical Products
(174-S2-100-2)		 100A Manual Firewall CONSTANT Bus
└→ 100A CB
   └→ BODY PDU		 ~54A max (radio 16A, USB 13A, camera 10A, seats 10A peak) 185% of max load (future expansion)

Wire Sizing for CB Protection

Forward feed uses 2/0 AWG (300A @ 20°C) for the 13-ft run to the firewall bus (now carries only SP+BODY, ~152A max; 2/0 retained for upgrade headroom). Firewall-side outputs use 2 AWG (130A @ 20°C) for SwitchPros and BODY PDU. Audio amp uses 4 AWG (95A @ 20°C, JL Audio minimum spec) for the short ~3-4 ft run from AUX battery to under-seat amp location.

Mechanical Products Series 17 (4 units):

  • Type: Surface mount
  • Reset: Manual (Type III - push to reset)
  • Terminals: 3/8"-16 studs (S2 configuration)
  • Dimensions: 3.39" L × 1.9" W (per unit)
  • Ratings: 48V DC (20-150A), 30V DC (175-200A), 14V DC (225-300A)
  • Standards: Marine-rated (SAE J1171, ABYC E-11, UL1500, IP67, MIL-STD-202)
  • Mounting: 2 at passenger rear wheel well (battery side: 300A + 150A), 2 at firewall (bus side: 150A SP + 100A BODY)

Blue Sea 187-Series (1 unit - Audio Amp):

  • Type: Surface mount
  • Reset: Manual
  • Terminals: 5/16" (M8) studs
  • Dimensions: 3.44" H × 2.32" W × 1.8" D
  • Rating: 5000A interrupt @ 12V DC
  • Standards: Ignition protected, waterproof
  • Mounting: Passenger rear wheel well (battery side, stacked with MP CBs on bracket)

Space Requirements:

  • Battery-side bracket: 3 CBs stacked (300A + 150A + 100A audio amp) — ~10" × 2" (~20 sq in) on wheel well bracket
  • Firewall-side cluster: 2 CBs in a row with wiring clearance — ~7" × 4" (~28 sq in) near bus