Blue Sea Systems 8690 Dual Battery Bank Management Panel - Manual (Page 2)

Wire Sizing Chart
1. Calculate the maximum sustained amperage of the circuit. Measure the
length of the circuit from the power source to the load and back.
2. Calculate Famps (Feet x amps). Multiply circuit length by max. current.
3. Base the wire on either the 3% or 10% voltage drop. In general, items
which affect the safe operation of the boat and its passengers (running
lights, bilge blowers, electronics) use 3%; all other loads use 10%.
4. Are the circuit runs in an engine space or non engine space?
5. Starting in the Famps column with the right voltage and voltage drop,
run down the list until arriving at a value which is greater than the
calculated Famps. Move left to the Ampacity column to verify that the
total amperage of the circuit does not exceed the maximum allowable
amperage of the wire size for that row. If it does, move down until the
wire ampacity exceeds the circuit amperage. Finally, move left to the
wire size column to select the wire size.
Example
A 12 volt system at 10% drop with a 40’ circuit x 45 amps = 1800 Famps.
A wire size of 8 is required.
Note: For wire with 105°C insulation rating and AWG wire sizes.
Chart courtesy of the West Advisor
Caution: ABYC Interrupt
In certain circumstances, main DC circuit breakers may have to break
very high amperages. The ability of a circuit breaker to safely break high
amperage is its Ampere Interrupt Capacity (AIC) rating. AIC is a function
of a battery’s Cold Cranking Amperes (CCA) capacity. According to ABYC
E-11 standards, circuit breakers shall have a DC voltage rating of not less
than the nominal system voltage, be capable of an interrupting capacity
according to the values in the table below, and remain operable after the
fault. For example, a boat with a group 24 or 27 battery may have as much
as 650 CCA. The DC main circuit breaker for this circuit must have an AIC
rating of 1500 Amperes.
Blue Sea Systems Battery Management Panels contain thermal (push
button reset) circuit breakers rated at 15A. These circuit breakers are
suitable for 24-hour circuits connected directly to 12V or 24V battery banks
with CCA capacities less than 660A.
Installation of this panel in systems with battery banks of 660A or higher
should include an additional fuse or circuit breaker of appropriate interrupt
capacity in the line between the battery bank and the pushbutton circuit
breakers to comply with ABYC E-11 and NFPA 302.
DC voltage rating CCA of all
connected
batteries
Ampere Interrupt Capacity (AIC)
Main Circuit
Breaker (Amperes)
Branch Circuit
Breaker(Amperes)
12 Volt and 24 Volt 650 or less 1500 750
651-1100 3000 750
over 1100 5000 2500
32 Volts 1250 or less 3000 1500
over 1250 5000 2500
GND SI LED
7610 ACR
2
1
1 2
LED LED LED LED
TO 24 HOUR
CIRCUITS
TO DC HOUSE
DISTRIBUTION
PANEL OR HIGH
AMP DC LOAD
100A
OUTPUT TO
ENGINE
ALTERNATOR
OR STARTER
ENGINE
HOUSE
DC NEGATIVE
DISTRIBUTION BUS
GND SI LED
7610 ACR
LED LED LED LED
TO 24 HOUR
CIRCUITS
TO DC HOUSE
DISTRIBUTION
PANEL OR HIGH
AMP DC LOAD
100A
OUTPUT TO
ENGINE
ALTERNATOR
OR STARTER
HOUSE
ENGINE
DC NEGATIVE
DISTRIBUTION BUS
LED
1
1 2
2
Wiring Diagram
Dual Battery Main Distribution Panel
PN 8686 Shown
Wiring Diagram
Dual Battery Main Distribution Panel
PN 8690 Shown