Blue Sea Systems PN 8081 Prospecto

 

Determine the proper wire size for each branch circuit using the    

 

guidelines in step 4. Verify that the standard 15 ampere 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 or yellow) branch circuit wire to the DC  

 

negative bus. DO NOT CONFUSE THE DC NEGATIVE BUS WITH  

 

THE DC GROUNDING BUS.

 

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 coming into contact with 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 interference (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.

 

A full treatment of this subject is not possible within the scope of these  

 

instructions and there is controversy surrounding the general subject of  

 

DC bonding, of which DC grounding is a component. It is suggested  

 

that installers not familiar with this subject consult one of the reference  

 

books listed elsewhere in these instructions.

DC Power Distribution Panel with Voltmeter and Ammeter

(PN 8081 / PN 3081 shown for reference)

  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.

Apply a label for each of the branch circuits from the 30 basic labels 

provided. If the appropriate label is not included, the Extended Label 

Set of 120 labels may be ordered from your marine supplier (PN 8039). 

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.

 

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. 

 

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. 

This Blue Sea Systems electrical distribution panel is 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 

amperes. Additionally, it would be rare to have more than 15 amperes of 

current fl owing in any one circuit. Therefore, 15 ampere circuit breakers 

will satisfy the vast majority of marine circuit protection situations.

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 runs 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.

a. 

A 12 volt system at 10% drop with a 40’ circuit  x 45 amps = 1800  

 

Famps. A wire size of 8 is required.