DC black and white wires

[Ann and David Brownlee]

I'm installing a new CD player in our 1983 Cape Dory 31, and I cut the wiring for the old unit before looking at it carefully and can't remember which is the positive wire. The DC wiring in our boat is all black and white. Which is which?

[jen1722terry]

Usually, the white is the neutral and the black is the positive (hot) wire. It's confusing.

Cheers

Terry

[Joe Mac Phee]

Danger!

In the domain of (AC) house wiring, black is the hot wire. In the domain of (DC) electronics, black is usually the ground wire.

On my boat, black is ground (negative). My positive wire is (almost always) red.

Use your voltmeter and actually measure it. Then look at the manual for the new player and make the positive and negative connections as instructed.

In my lab, the rule was all electronics require smoke to operate. If you do anyhting that lets the smoke out, it will no longer run. Be careful.

Joe

[tjr818]

Danger!

In the domain of (AC) house wiring, black is the hot wire. In the domain of (DC) electronics, black is usually the ground wire. . .

I believe that the new rules require DC negative wiring to be yellow to avoid that confusion. That is the way all new DC wiring is on Slainte, but try to find a yellow battery cable. I could not.

[Sea Hunt Video]

In my lab, the rule was all electronics require smoke to operate. If you do anyhting that lets the smoke out, it will no longer run. Joe

Joe:

I am "electron challenged". Could you explain (decipher) the smoke analogy

Thanks

[Joe Mac Phee]

If you have to explain a joke, it isn't funny. Sorry for the obscure joke. The joke was borrowed from the world of old English cars with Lucas electric components.

Ignore any reference to the joke, it is a diversion from the original issue about getting the correct polarity connection on the CD player.

Mea Culpa,
Joe

[GeorgeH]

I have had some some electrical problems on my boat recently and I am not sure this thread made it any easier to know what wires Are positive and negative. From what I just read:

1. If there are black and white wires, then white is nuetral/ground and black is positive/hot.
2. If there are black and red wires, red is positive/hot and black is neutral/ground.
3. If there is a yellow wire, it should be the neutral/ground?

My battery has red and black connectors and I always attach the red connector to the positive post. My Yanmar engine has red wires to the starter and alternator and I assume they are positive/hot.

Good advice about using a voltmeter. Anything else I should be aware of or concerned about.

[Maine Sail]

Guys,

Back before builders built to a "Standard" there really was no standard. Duplex wire in black / white was cheap so builders used it, very often diminutive 16GA to boot.. Some made Black DC Negative and some made White DC Negative. There was NO STANDARD when the wrong colors were used for DC wiring so it needs to be physically confirmed.

Lots of builders in the 70's & 80's used Black & White but about half did it one way and the other half did it the other way. Confirm before proceeding!!

[jen1722terry]

That's good advice from Maine Sail, as always.

Voltmeters are cheap, even available at Walmart. With the apparent confusion in wire color/use, why not take a minute to check the wires before you turn on the juice. I usually do, but not always and have had no problems, yet. All that proves is that I'm lucky. Check with a meter.

And happy fall sailing to all of you.

Jenn and Terry

[RIKanaka]

Voltmeters are cheap, even available at Walmart.

Sometimes free even, at Harbor Freight. Getting them to work, however, is often another matter.

[Ann and David Brownlee]

Well, I have a multimeter, and I should have checked the polarity. I'll report back, but I think black is positive.

Here's another, follow-up question. The new CD player has three power wires (unlike the 2 on the old unit): red, yellow and black. Common sense and the accompanying wiring diagram suggest that the red goes to the DC positive (hot), the yellow goes to DC "negative," and the black snakes down to the boat's grounding plate (providing a real ground, which the old unit lacked). But a boat electronics installer on another discussion board says the red and yellow should BOTH go to the DC positive, while the black goes to DC "negative."
Thoughts?

[Maine Sail]

Well, I have a multimeter, and I should have checked the polarity. I'll report back, but I think black is positive.

Here's another, follow-up question. The new CD player has three power wires (unlike the 2 on the old unit): red, yellow and black. Common sense and the accompanying wiring diagram suggest that the red goes to the DC positive (hot), the yellow goes to DC "negative," and the black snakes down to the boat's grounding plate (providing a real ground, which the old unit lacked). But a boat electronics installer on another discussion board says the red and yellow should BOTH go to the DC positive, while the black goes to DC "negative."
Thoughts?

Red 12V+ Switched Power - To load side of DC stereo breaker

Yellow 12V+ Constant Power - To always on Battery + bus. This saves memory and is your main high current power wire for the unit which drives the amp.

Black 12V Negative - To the negative battery bus.

[hilbert]

I am "electron challenged". Could you explain (decipher) the smoke analogy

What if you pluck someone out of a remote village, who has never seen an electronic device. He doesn't understand how it works, but it does until one day it stops when smoke comes out of it. A logical assumption would be that it stopped working because the smoke escaped and one would need to put the smoke back for it to work again. The moral of the story is not to do anything that lets the smoke escape.

[Ann and David Brownlee]

White is the hot (+) wire on my 1983 boat.
CD player works fine. Thanks to all.

[Joe Myerson]

If you have to explain a joke, it isn't funny. Sorry for the obscure joke. The joke was borrowed from the world of old English cars with Lucas electric components.

Joe,
I remember those damn Lucas components! Some of the smoke came out of my ears every time I worked on that MG--Ugh!

--Joe