Proper marine wiring practices are difficult to come by these days, so I have
put together a short informational packet on how to properly tackle a wiring
project on your boat.
Most importantly, you should always follow the color-coding
standard used in the industry when adding or replacing the wiring in your boat.
The 12volt standard is as follows:
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Black - Common ground for the electrical system
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Red - Main (+) for the electrical system
-
Purple - Accessories positive lead between key switch and positive lead
of accessory
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Purple w/white stripe - Positive lead between key switch and choke
solenoid on engine
-
Yellow w/red stripe - Positive lead between key switch and starter
solenoid
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Red w/white stripe - Positive lead feeding power to individual solenoids
on an engine
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Brown - Positive lead for pumps like bilge or wash down
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Tan - Sender lead for temperature gauge
Pink - Sender lead for fuel sender in fuel tank
Dark Blue - Lighting - primarily in instrument panel gauges
Gray - Navigation lights
Light Blue - Oil pressure sender lead between engine oil pressure sender
and gauge "S" terminal
Orange - Alternator output lead which connects to starter solenoid
positive post to recharge batteries
Yellow - This color in a solid form is seldom used but can be used for
windshield wiper circuits
Green - Vessel earth ground which is used in bonding circuits to provide
an earth ground to the vessel
Orange w/yellow stripe - Horn positive lead
Purple w/red stripe - Blower positive lead as well as accessories such as
nav equipment and radios
Tan w/ stripe - Warning circuit between sender and alarm circuit, match
stripe color to sender type, ie blue for oil, brown for temp etc
With the use of proper color-coding, your service tech will
be able to quickly solve wiring problems. Next we will look at what kind of
wire to use. I always use tinned stranded electrical wire because it resists
corrosion far better than any other wire. Your wire must have an insulation
temp rating of at least 105 degrees C to be coast guard approved. Never
use wiring not designed for marine use. For connections, there are several
options. Solder and heat shrink is the best, followed by crimped terminals
which use an epoxy sealer in the heat shrink tube which is part of the
terminal, and lastly, the standard insulated crimp terminal.
As a good practice, you should always use shielded power cables for connecting
electronic equipment. The use of shielded cables will reduce electrical
interference and allow you to get the best reception.
Wire size is as important as everything else. Always use the proper size wire
for the electrical load it will be carrying. If you have a 10 amp circuit less
than 20 feet in length, use 14 gauge wire. Use 12 gauge if it is less than 30
feet. For circuits which are relatively short use a wire gauge one size larger
than the size wire the accessory you are connecting provides.
Always provide fuse protection for your circuits, including the main feed from
the battery to the fuse panel and keep it as close to the source as possible.
If you have a specific question regarding a project you are working on, feel
free to contact us anytime. We are always happy to assist our customers.
Lately we have had a lot of you looking for information on marine wiring. For
instruments, always maintain seperation from your boats auxilliary systems. All
guages are to be wired into the engine harness and power supply. Use the ground
wire (black) from the key switch end of your engine harness for the ground
terminals on your guages. Use the purple accessory lead for your ignition
terminals and the individual sender leads for the sender terminals. Connect fuel
senders sererately and with a direct battery ground lead. To test a guage and
sender for proper function, with power to guage on, ground the sender terminal
of the individual sender to a known ground, this will cause the guage to move to
it's full position. If it does not move, the guage is bad, if it does move when
grounded but not in normal operation, then the sender is defective.
If you have a specific question you need answered, feel free to email it to us
at service@marinesurveysplus.com
and we will be happy to reply with an answer.