>Terminal Blocks and Bus Bars
Terminal Blocks and Bus Bars2018-06-05T07:30:43+00:00

Terminal Blocks & Bus Bars

An essential part of your boat’s electrical system, terminal blocks and bus bars make convenient connection, troubleshooting and aggregating points.

30A Terminal Blocks
Marine grade 30A terminal block
10 Circuit Bus Bar
Boat Negative Bus Car 10 circuits
20 Circuit Bus Bar
20 circuit marine bus bar with screws

What is a Terminal Block?

Our quality – tinned, marine grade terminal blocks are of huge benefit on most re-wire jobs.  A terminal block – sometimes called junction block – is a convenient connection point for two wires.

It acts like a bunch of splices, but in an organized way.  Each ‘circuit’ has two adjacent screw terminals connected by metal plates.  This is distinctly different than a ‘bus bar’ where all the conductors attached to it are “bussed” together.

Extremely common on boats, especially where the switch panel connects to the boat’s wiring infrastructure.  These marine grade terminal blocks are what our switch panels are designed to attach to.

We carry them in 4, 6, 8, 10, 12 and 20 circuits.  They screw under the dash with a few wood screws, or can be epoxied in. Sized for #8 ring terminals.

A switch panel wired to a terminal block

Switch panel showed wired to one of our 30A terminal blocks

What is a Bus Bar?

marine grade bus bar and terminal block comparison

(Click to Enlarge)

Unlike a terminal block, a bus bar gangs all the studs or terminals together into one ‘bus’.  This makes one electrical ‘node’ of the same potential (voltage level).

A bus bar is designed to make a solid connection point from one source to many branch circuits.  Or many branch circuits back to a single source.  More often than not a bus bar is used on the negative side of the circuit, because the switch panel is used as the positive source distribution method.

Being one electrical ‘node’, bus bars are used to place many loads in ‘parallel’ with each other… which is how your boat’s electrical loads need to be placed.

This side-by-side comparison of a marine terminal block and bus bar clearly shows the difference in design and use of the components.

How are terminal blocks and bus bars used in your boat’s system?

See below for examples of how terminal blocks and bus bars are used in a typical boat’s electrical system.  The terminal block connects the switch panel outputs to the wires going out to the device.

There’s almost always at least one bus bar on a boat… used to aggregate (combine) all the negative’s together coming from the loads.  This allows only one – larger – conductor to be run from the battery to the helm.  If you don’t see one on your boat, then it’s probably built into a fuse block.

Terminal Block and Negative Bus Bar Wiring Diagram

marine terminal block and bus bar wiring diagram

(Click to Enlarge)

Example Uses On Boats