Home' Afloat : AFLOAT July 2015 Contents 50 AFLOAT.com.au July 2015
by Kurt Küpper*
* Kurt Küpper is director of Aquavolt
Electric Boat Parts. Tel: 02 9417 8455
So what else would you like to know? You are welcome to send in questions about
boat electrics or suggestions for topics that you would like explained.
Terminating DC wire connections
Apart from failures in wire runs
through pinching, chafing or contact
with hot surfaces, almost all wiring
failures occur at the terminations at the ends
of the wire. Never twist wires together to
make a connection, and never wrap a bare
wire around a terminal screw.
There are two schools of thought on
the relative merits of using crimp terminals
versus soldering. Soldered joints can create
a brittle area which can eventually break due
to vibration. If you don’t spread the cable
strands evenly in a screw connector this
can exacerbate corrosion. It is also much
easier and safer to use a crimp tool on
board. So crimp connectors have become
the generally recommended method of
Poor connections cause resistance to
current flow, resulting in voltage drop and
heating, which can lead to complete failure
or even fires. Each cable run must be
correctly terminated so that the right voltage
is present at the appliance, under load.
There must be good contact between
cable and terminations, requiring adequate
contact area and pressure, free from
corrosion, paint and other insulating
materials. The termination must also
be in firm contact with the terminal it is
Every crimp connection is a potential
trouble spot. It is thus essential to match
the crimp connector to the cable and the
equipment to which it is being terminated.
Terminals used on a boat must always be
copper, never steel or aluminium, and like
the wire, should be tin-plated to resist
Most connections for light duty cable
are made with insulated crimp connectors.
The insulation of these is colour coded to
indicate the cable size for which they are
• Red – conductor 0.5 to 1.5mm2
• Blue – conductor 1.0 to 2.5mm2
(2mm2 or 4mm auto cable)
• Yellow – conductor 2.5 to 6.5mm2
(5mm2 or 6mm auto cable)
There are many types of crimp
connectors including: ring, fork, spade (aka
quick connect or QC), piggy back, splices
(inline butt splices or blind end splices),
bullet, and pin (wire or flat, for use in screw
down or crush type connectors).
Captive ring connectors are the best
connection to choose. Although fork
connectors are easier to install than ring
connectors, they are more likely to be pulled
off, and are therefore not recommended.
Butt splices should be used for
appliances supplied with wire leads instead
of terminals. To simplify servicing, it may
be necessary to make the connection
with pairs of blade or bullet connectors
instead of butt connectors. Here again, it
is safer to use ring terminals plus suitable
terminal blocks to reduce the danger of the
connection pulling apart.
In wet areas, waterproof crimp
connectors should be used. These are
usually butt splices which
use heat shrink tubing as
Stripping wire with a
knife can damage the plating.
Proper wire strippers are
not expensive and strongly recommended.
Avoid using budget crimp tools and
definitely don’t use pliers or a vice. For
occasional use, basic pliers-type crimpers
are adequate, but for regular use and larger
projects, the only proper tool to use is a
ratchet crimper. It will not release the crimp
until sufficient pressure has been applied,
but it will not allow excessive pressure to be
applied, which might damage the terminal.
You will be glad you invested $75 for a good
crimper every time you use it.
Ensure that there is good electrical
connection between the cable and
terminal. Many amateurs have crimped onto
insulation. Ensure that enough insulation
has been stripped back from the cable to
allow full contact between the conductor
and the terminal and check that the tip of
the conductor just protrudes from the front
of the crimp barrel.
After the job is done, test every crimp
by giving the cable a decent tug.
Larger crimps for battery and winch
cables require heavy duty crimp tools that
are similar to swaging tools. They commonly
have different dies for different cable and
terminal sizes. It goes without saying
that correct matching of cable, terminals
and crimping dies, is essential for good
These tools are expensive and the
average boat owner cannot justify their
purchase. Ask your electrician or electrical
supplier to crimp these or purchase pre-
made cable assemblies (make sure that the
cable is tinned!).
Wires should be supported close to
terminations where possible to avoid
unnecessary load on terminals. h
Aquavolt has moved a
few doors closer to the
Roseville Bridge from
No11 to No29E.
We look forward to
welcoming you to our
29E Babbage Rd, E-Roseville NSW 2069
Tel: 02 9417 8455
Fax 02 9417 8423
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