Blue Sea Systems 8379 DC Main + 20 Positions, White Toggle - Manual (Page 2)

Installation
(continued)
7. Install branch circuit wires
Determine the proper wire size for each branch circuit using the
guidelines in step 4. Verify that the standard 15 amp circuit breakers
installed in the panel are large enough for each branch circuit. Remove
and replace with a higher amperage any that are undersized. Connect
the positive (red) branch circuit wires to the load terminals of each circuit
breaker. Connect each negative (black) branch circuit wire to the DC
Negative Bus. DO NOT CONFUSE THE DC NEGATIVE BUS WITH THE
DC GROUNDING BUS.
8. Installation of Backlight System
Connect the yellow negative wire to the panel negative bus.
To activate the label lights by the boat’s battery switch, connect the red
positive wire to the DC panel positive bus.
To activate the label lights by an independent switch or breaker, connect
the red positive wire to the load side of the switch or breaker.
9. Optional - install grounding system wire
The grounding wire (bare, green or green with yellow stripe and normally
non-current carrying) should not be confused with the negative ground
wire (black or yellow and normally current carrying).
In Boatowner’s Illustrated Handbook of Wiring, Charlie Wing identifi es
three purposes of DC Grounding:
1. Holding conductive housings of low voltage (under 50 volts) DC
devices at ground potential by providing a low resistance return
path for currents accidentally contacting the device cases.
2. Providing a low resistance return path for electrical current,
preventing stray currents that may cause corrosion.
3. Grounding metal electrical cases to prevent emission from inside
or absorption from outside of radio frequency noise (RFI).
ABYC requires that grounding wires be sized no smaller than one wire
size under that required for current carrying conductors supplying the
device to which the grounding wire is connected.
10. Apply branch circuit labels and mount panel
Apply a label for each of the branch circuits from the 60 basic labels
provided. If the appropriate label is not included, AC and DC Extended
Label Sets of 120 labels each may be ordered from your marine supplier
(PNs 8039 and 8067). Individual labels are also available from Blue Sea
Systems for specifi c applications. Refer to the label order form for a
complete listing of individual labels.
Fasten the panel to the mounting surface using the panel mounting
screws supplied with the panel.
11. Testing
@ Reconnect the main positive cable to the battery terminals and turn
the main switch on to supply power to the panel. Turn on all branch
circuits and test the voltage at the panel. Compare this voltage to the
battery terminal voltage to determine that the voltage drop is within
3%. With all branch circuits still on, test the voltage at one device on
each circuit to determine that there is a 3% or 10% drop as is
appropriate.
@ Turn on each branch circuit to verify power to each circuit.
@ Review the DC meter installation and operation manual.
Reference the Theory of Operation, Use, Installation Overview and
operations sections. Verify meter functions.
Optional Branch LED’s
This panel is supplied with LED’s pre-installed in all optional branch
positions. For future expansion of the panel remove the positive leg of
the LED from the negative bus and connect it to the load side of the
corresponding branch circuit breaker.
Note
All Blue Sea Systems’ DC electrical distribution panels are furnished
with 15 amp AC/DC circuit breakers. This rating was selected to minimize
the need for removing the panel’s circuit breakers and reinstalling
different size circuit breakers. As shown in the Wire Sizing Chart included
with these instructions, even 16 AWG wire, which is the minimum wire
size recommended by ABYC, has an allowable amperage greater than
20 amps. Additionally, it would be rare to have more than 15 amps of
current fl owing in any one circuit. Therefore, 15 amp circuit breakers will
satisfy the vast majority of marine circuit protection situations.
Page 2 of 3
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. Does the circuit run in an engine space or non engine space.
3. Calculate Famps (Feet x amps). Multiply circuit length by max. current.
4. 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%.
5. Starting in the column which has 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.
A 12 volt system at 10% drop with a 40’ circuit x 45 amps = 1800
Famps. A wire size of 8 is required.
Reference
Applicable Standards
• American Boat and Yacht Council (ABYC)
Standards and Recommended Practices for Small Craft sections:
E-1, E-3, E-9.
• United States Coast Guard 33 CFR Sub Part 1, Electrical Systems
The Purpose of a Panel
There are fi ve purposes of a marine electrical panel:
• Power distribution
• Circuit (wire) protection
• Circuit ON/OFF switching
• Metering of voltage and amperage (In panels with meters)
• Condition Indication (circuit energized)
Useful Reference Books
Calder, Nigel, 1996: Boatowner’s Mechanical and Electrical Manual,
2nd edition, Blue Ridge Summit, PA: TAB Books, Inc.
Wing, Charlie, 1993: Boatowner’s Illustrated Handbook of Wiring,
Blue Ridge Summit, PA: TAB Books, Inc.
Guarantee
Any Blue Sea Systems product with which a customer is not satisfi ed
may be returned for a refund or replacement at any time. Reference Blue
Sea Systems’ Digital Meter installation manual for specifi c meter
warranty information.
Related Products from Blue Sea Systems
High Amperage Fuses and Circuit Breakers for positive feed wires
High Amperage Battery Switches
Terminal Blocks and Common Bus Connectors
AC and DC Voltmeters and Ammeters
Questions and Comments
We invite your questions and comments. You may contact us at
the address above or by email at [email protected]. To fi nd out
more about our full line of marine electrical products visit our web site at
www.bluesea.com.