Vehicle Wire Color Standards

DaveInDenver

Middle Income Semi-Redneck
There are many standards for low voltage wiring and even some that specify the color used. As far as I know, though, there's not a unified SAE for vehicles. But the convention for accessories is red is +12V and black is battery return.

The British BS-AU7 depreciates red to a switched use (side marker lights or something I think) in favor of purple and brown for mains, but I don't know if this has any adherence. Boats generally follow the automotive standard for red being mains, black or yellow as return, green would be grounding.

My question here is what color do people use for derived voltages? In my specific case I'm wondering if anyone has selected a common for +5V rails on trucks and motorcycles. I'm trying to select a Powerpole housing color to use for a GPS power lead on my motorcycle and my inclination is to select grey or white. The wire itself will be red but the connector being odd should at least give a visual warning not to do something dumb.
 

AndrewP

Explorer
I am not aware of vehicle standards, though GM harnesses all use a standard color scheme.

On boats, the grounds are often yellow, to avoid confusion with A/C hot when moored to the dock with shore power.

You may need to just label your wiring to avoid future problems. I thought this was reasonably clever:
http://www.pbase.com/mainecruising/wire_labeling
 

DaveInDenver

Middle Income Semi-Redneck
Most vehicle manufactures have an internal standard that they use and can extend to subcontractors. The ABYC allows in marine use either black or yellow for current return (battery negative) and specifies green or green/yellow stripe for ground. But it seems red is pretty universally considered battery hot for accessories but purple, blue, all sorts of colors mean different things in your vehicle harness.

I have a Brady label maker, so it's not so much about marking the wires to match a wiring diagram. I'm mostly wondering what people do and think about secondary voltages that are not battery level and in the case of the power lead to a GPS could be damaging if connected by mistake. You may be able to infer why I'm asking. FWIW, a replacement Garmin 18x LVC is about $60 at the moment on eBay...
 

proper4wd

Expedition Leader
My scheme is pretty basic, Bright colors for + (red, orange, yellow, etc) and dark colors for ground (black, brown, gray).
 

DaveInDenver

Middle Income Semi-Redneck
Unless you want to adopt a colour whats standardised to some manufacturer, You are probably on your own.

Fwiw. If NEC applies. All grounded conductors must be white or natural grey. Includes DC circuits.
Article 200.7(B) would not apply because it states white or grey only under conditions in 250.20(A), which states under 50V AC when that is supplied by a transformer that exceeds 150V to ground. The NEC stipulates DC grounding in Article 250 VIII and in that they are only concerned with DC above 50V or those derived from a rectified AC branch. I don't think NEC applies at all to vehicles beyond Article 625.

FWIW I picked violet for my +5V. It seemed as good as any since I had a roll of wire with purple insulation. I decided against orange because I can't tell the difference between it and red unless it's in bright sunlight. Yellow is also hard for me to distinguish from red, it's more a variation of shade between them all.
 

Charles R

Adventurer
Yeah, the color schemes vary pretty greatly per manufacturer.

The German cars typically use red for constant +12v, black for keyed +12v, and brown for ground.
For circuits that are controlled by switching grounds, (ie computer control grounds the circuit) the wire tends to be brown with a color stripe. I can't recall the other patterns of the top of my head right now though.

When i used to wire up dune buggies and race cars, i would use the German power colors. For switched circuits, I used whites and yellows for lights, and blues and greens for accessories. It was kind of a "the brighter/whiter the wire was, the more important the circuit was, mentality.
 

rayra

Expedition Leader
Take a look at the car stereo world, there's some common standards there. But most of it is covered already. The NEC is a good fallback. My suburban has 12V in red, orange, violet. I haven't noticed a correlation with amperages.

I've used black-clad 1/0 for a main battery power bus in an Aux setup and rear bumper power install and marked the hot / (+) with red electrical tape at its ends, akin to the NEC specs when you use the wrong color wire.

auxbatt051%20Aux78_zpspz2aylim.jpg
 

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