Technical article from Blue Sea Systems
Busbars perform a very simple but important function in a boat's electrical system:
- To distribute power from a large positive conductor to individual circuit protection devices feeding a number of smaller wires
- To collect small negative conductors and step them up to large ones
As the proliferation of appliances increases in boats, performing this function becomes increasingly important. Space is more confined, there are more wires to connect, more current to carry, and organizing and labeling wire connections is more important.
On all but the smallest boats, it is impractical to attach all of the wires from each load directly to the battery terminal or to the battery switch terminal. Large boats may have many layers of progressively smaller busbars, smaller boats may have only one small busbar.
Early busbars were made of brass attached to uninsulated bases. The first generation Blue Sea Systems busbars included many improvements:
- Tin-plated copper -- Copper is 250% more conductive than brass. Better conductivity means less internal resistance, lower voltage drop, and therefore less heat. Copper busbars safely carry more current than brass busbars. Tin plating reduces the corrosion for maximum conductivity and resistance to corrosion.
- Stainless steel screw terminals with captive lock washers-- High torque connection for small wire terminals, no risk of loosing washer. Multiple connections for small wires.
- Stainless steel terminal studs-high torque, will not corrode. In a distribution bus, the terminal stud is a compressive element, not a conductive element. Its purpose is to press the ring terminal surface securely against the busbar.
- Insulating cover to protect connections from shorting out-- The insulating cover provides insulation for all wires connected to busbar. This is especially important when the busbar is on the positive side of the circuit.
Blue Sea Systems has continued to make improvements to its busbars. Most recently, significant improvements have been made to the popular 150 Ampere busbars, models 2300 (with cover), 2301, 2303, and 2307 (with cover).
The table below provides a description of each improvement.
||Because the bus is pressed on to the stainless steel terminal studs, it doesn't require a securing nut that can come loose. In addition, there is a direct compression connection between the copper busbar and wire terminals instead of to a retaining nut.
|Insert molded stainless steel studs
||In a distribution bus, the terminal stud is a compressive element, not a conductive element. Its purpose is to press the ring terminal against the busbar. Stainless steel studs molded into the base allow for high torque and therefore a tighter connection and lower resistance.
|Press-on insulating cover
||The insulating cover provides insulation for all wire terminals connected to the busbar. This is especially important when the busbar is on the positive side of the circuit. Also, cover design allows for terminals to be attached to the busbar from any direction.
||Raising the busbar above the surface of the base provides unobstructed wiring access, and allows for terminals to be inverted so that multiple terminals can be attached to each stud and screw.
|Heat resistant base material
||Base material made of reinforced polycarbonate resists high heat-it will not burn in the absence of a flame.
In addition to its 150 Ampere busbars, Blue Sea Systems manufactures an extensive assortment of busbars to meet the needs of nearly every electric circuit distribution and collection application. The table below provides a summary of some of the categories of busbars.
Great for negative conductor collector, or positive conductor distribution. Add a busbar to a circuit instead of cutting into the harness when adding appliances or lights. Not knowing what buyers will want to add, some boat builders add busbars into circuits.
|2300 - with cover, 1/4" stud terminals, 10 x #8 screw terminals; 130A AC, 150A DC
2301 - without cover, 1/4" stud terminals, 10 x #8 screw terminals, 130A AC, 150A DC
2302 - without cover, 1/4" stud terminals, 20 x #8 screw terminals, 130A AC, 150A DC
2707 - cover for 2302
These "busbars in the round" are ideal for confined spaces, large wire connections. The PowerPost (without screw terminals) is not rated-current flows between terminals stacked on the post. Wire size determines acceptable current flow.
|2010 - #10 stud terminal
2011 - 1/4" stud terminal
2001 - 1/4" stud terminal
2002 - 5/16" stud terminal
2003 - 3/8" stud terminal
The Powerpost Plus performs a similar function as the 2300 but is ideal for confined spaces and small wire connections.
|2101 - 1/4" stud terminal, 5 x #8 screw terminals, 150A AC/DC
2102 - 5/16" stud terminal, 5 x #8 screw terminals, 150A AC/DC
2103 - 3/8" stud terminal, 5 x #8 screw terminals, 150A AC/DC
This high-current busbar is built for high amp loads, for example, when connecting multiple battery banks, or connecting charger output to multiple battery banks. Large 3/8"-16 stud terminals for large terminal connections, plus four #8-32 screws for small terminal connections.
|2104 - 4 x 3/8" stud terminal, 4 x #8 screw terminals, 545A AC, 600A DC
2107 - 8 x 3/8" stud terminal, 4 x #8 screw terminals, 545A AC, 600A DC
2708 - cover for 2104
Combined positive and negative busbars, screw terminals, no terminal studs. Cover available separately.
|2701 - 5 x #8 screw terminals, 100A AC/DC
2702 - 10 x #8 screw terminals, 100A AC/DC
2709 - cover for 2701
2710 - cover for 2702
Combined positive and negative busbars, with integrated cover, stud and screw terminals.
|2720 - 1/4" stud terminals, 130A AC, 150A DC
2722 - 1/4" stud terminals, 5 x #10 screw terminals, 130A AC, 150A DC
2723 - 5/16" stud terminals, 5 x #10 screw terminals, 130A AC, 150A DC
Original article from Blue Sea Systems