Which 12V wire is hot?

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Which 12V wire is hot?

September 24, 2010, 12:15:11 pm

I am thinking the white wire is hot on our coaches, why else can I not remember this?

For the record, set me straight.

Is the white wire HOT?

Re: Which 12V wire is hot?

Reply #1 – September 24, 2010, 12:36:26 pm

George, my recollection is that white is ground and blue is hot on the 12V system but let's have others verify.

Re: Which 12V wire is hot?

Reply #2 – September 24, 2010, 12:51:46 pm

On my coach the white is ground, Blue +12 vdc

Re: Which 12V wire is hot?

Reply #3 – September 24, 2010, 02:53:15 pm

In Foretravels the 12 v system "Green" is "Ground" always...Remember the G's for ground & green.

Re: Which 12V wire is hot?

Reply #4 – September 24, 2010, 03:08:29 pm

But Pete, I don't have any green wires.

Re: Which 12V wire is hot?

Reply #5 – September 24, 2010, 03:13:15 pm

Quote from: Kent Speers – September 24, 2010, 03:08:29 pm

But Pete, I don't have any green wires.

Kent,
Do you have the wiring diagrams? That will tell you. If no one else gives you an answer, it's time to give Mr. Triana a call...

Re: Which 12V wire is hot?

Reply #6 – September 24, 2010, 03:26:53 pm

But Pete, George is the one that wants to know. I got not wiring problems.

Re: Which 12V wire is hot?

Reply #7 – September 24, 2010, 03:28:22 pm

Green is ground for the 120 VAC wiring. May or may not be for 12 VDC.

Brett Wolfe

Re: Which 12V wire is hot?

Reply #8 – September 24, 2010, 03:33:21 pm

Boy, wouldn't that be the pits if Peter is color blind. Blue? Green? there pretty close to one another. Watch out Pete if you are doing any rewiring.

Re: Which 12V wire is hot?

Reply #9 – September 24, 2010, 03:47:34 pm

Quote from: Kent Speers – September 24, 2010, 03:33:21 pm

Boy, wouldn't that be the pits if Peter is color blind. Blue? Green? there pretty close to one another. Watch out Pete if you are doing any rewiring.

Now I'm not sure...confused... I had to call James T. when I did the TV remodels cause I couldn't remember how to re-wire up the antenna booster in the front cabinet. I blew a 12v fuse once and after calling James, he informed me that the green is always ground. I guess the antenna boost in 120v?

Re: Which 12V wire is hot?

Reply #10 – September 24, 2010, 04:18:21 pm

My method is "touch it to your tongue". What don't kill ya makes ya stronger.

Re: Which 12V wire is hot?

Reply #11 – September 24, 2010, 06:49:32 pm

Quote

For the record, set me straight.

Is the white wire HOT?

George,
On our year model the white is the hot and green is ground on the 12 volt system.

Safe travels,

Brad

2000 U320 4000

Re: Which 12V wire is hot?

Reply #12 – September 24, 2010, 10:09:56 pm

I think this deserves a little more discussion.

"Ground" is a confusing term. In 120v speak, it means a third wire that is the neutral and connected to ground. In 12v speak, it is the negative side of the battery and obviously an essential part of the 12v system. Cars have 12v chassis ground in that you only need one wire to set up a 12v fixture , the other side of the fixture is connected to the chassis and finds its way back to the battery. In RVs, there is a separate 12v negative ("ground") wire. (I think for all 12v fixtures - but not sure.)

To add to the confusion, the standard for 120v ground wires is green - I have never seen anything else. But what is the standard for 12v negative / ground ? Black, green or what ever.

Now some more fun - by calling the 12v negative wire, a "ground" wire, (and since in my coach, it is also green) I have been thinking that ground is ground and that it is the same as the 120v ground.

But what if part of the 120v wiring fails, or you connect to badly wired shore power and the 120v ground becomes hot - and - that 120v ground is connected to the 12v ground? Not good.

12v ground wires are kept separate and all go back to the battery. I don't have wiring diagrams with me so someone please verify all this.

I have been thinking that a modification I did has broken this separation of 12v and 120v grounds. I added the Toad-Charge system and connected 12v positive (through a circuit breaker) to the engine batteries at the isolator. The 12v negative (ground) I used was the closest available - the green wire in the 120v circuit breaker area at the foot of the bed. I am not plugged into shore power, haven't started the generator or turned on the inverter so I haven't caused any problem ---in fact, the system worked fine and charged the toad --- but I WILL be finding a more appropriate spot for the 12v negative.

Make sense?

Re: Which 12V wire is hot?

Reply #13 – September 24, 2010, 10:15:05 pm

Larry,

I am glad I was able to help you out.

Re: Which 12V wire is hot?

Reply #14 – September 24, 2010, 10:23:07 pm

George ---- by all means, I need all the help I can get.

Re: Which 12V wire is hot?

Reply #15 – September 24, 2010, 10:37:16 pm

Quote from: Larry Rubin – September 24, 2010, 10:09:56 pm

I think this deserves a little more discussion.

"Ground" is a confusing term.

The 12v negative (ground) I used was the closest available - the green wire in the 120v circuit breaker area at the foot of the bed.

Make sense?

"Ground" confuses many people. The biggest misconception is that it's a giant sink where all electrons/holes flow to zero potential (0 volts). Such is not the case.

For us (former) EMC engineers, there are a variety of things called "ground", none of which really are what the assumption of "ground" means. For 120V a/c systems with green wires, "Ground" is the 3rd wire, connected somewhere to a copper rod sunk into the earth, and used for safety concerns (aka "safety ground" or "earth ground"). For automotive/RV DC systems it's related to the battery/chassis/DC power supply, which isn't directly connected to the "safety ground" (where's the copper rod sunk in the earth?). It's more of a lowest-potential reference. So they are (for most applications) separate systems.

An EMC colleague once (and still) said it best "Ground is the place where carrots and potatoes grow".

Michelle

Re: Which 12V wire is hot?

Reply #16 – September 24, 2010, 10:44:07 pm

So whence did thou cometh, AMD, Motorola, TI?

Re: Which 12V wire is hot?

Reply #17 – September 24, 2010, 10:49:22 pm

Michelle -

I worked at EMC (Storage) from 1995 - 2002 when I went to Cisco.

Tim Fiedler

Re: Which 12V wire is hot?

Reply #18 – September 24, 2010, 10:54:19 pm

Quote from: Kent Speers – September 24, 2010, 10:44:07 pm

So whence did thou cometh, AMD, Motorola, TI?

I you mean me, IBM. Can't you tell from my Bruce Archambeault quote?

BTW EMC for me means Electromagnetic Compatibility. Some folks might call it EMI, but for IBM that was "early manufacturing involvement" (did that, too).

I worked on the circuit board end of things, not the 10M chamber testing (directly). Also have some signal integrity, semiconductor processing, and electronic packaging experience. I could probably still run a high vacuum deposition system, but please don't ask me to build a SPICE deck....

Michelle

Re: Which 12V wire is hot?

Reply #19 – September 24, 2010, 11:17:15 pm

IBM, are they in electronics?

Re: Which 12V wire is hot?

Reply #20 – September 24, 2010, 11:36:00 pm

Quote from: Steve & Michelle – September 24, 2010, 10:54:19 pm

Quote from: Kent Speers – September 24, 2010, 10:44:07 pm
So whence did thou cometh, AMD, Motorola, TI?

I you mean me, IBM. Can't you tell from my Bruce Archambeault quote?

BTW EMC for me means Electromagnetic Compatibility. Some folks might call it EMI, but for IBM that was "early manufacturing involvement" (did that, too).

I worked on the circuit board end of things, not the 10M chamber testing (directly). Also have some signal integrity, semiconductor processing, and electronic packaging experience. I could probably still run a high vacuum deposition system, but please don't ask me to build a SPICE deck....

Michelle

Boy...Do I Feel Inferior...I Worked for a Banana Company....

All seriousness aside, though, what is considered the negative terminal of the starting batteries which is "grounded" to the chassis frame? I understood this to be the ground, eventhough this never really reaches the real ground? So, therefore, if a 12v fixture (load) takes its power from the + terminal of the battery, it can be "grounded" to any metal that is an integral part of the chassis frame?

Re: Which 12V wire is hot?

Reply #21 – September 24, 2010, 11:55:27 pm

The bottom line is on my coaches, the blue wires go to the positive post of the 12V battery and the white wires to the frame.

Re: Which 12V wire is hot?

Reply #22 – November 14, 2010, 09:59:48 pm

I thought this topic would be centered upon the question of what items in the coach are continually connected to the battery.... This is a concern for me to control phantom loads and such during storage.

Recently, while finally locating the HWH power fuse thanks to this forum and/or Mr. Barry (in the drivers side main storage bay behind a fiberglass enclosure and near the vacuum cleaner assembly in our 96 36' U270) I discovered two 12 volt busses. One seems to be "Hot" all the time and the other is switch controlled.

Because I want to have the battery switch (by the steps) off but still have the furnace motor able to run if the night time temps drop cold enough, I am wanting to move the furnace power to the hot bus. Anyone see problems here? (Other huge battery usage.)

andy

Re: Which 12V wire is hot?

Reply #23 – November 14, 2010, 10:45:54 pm

Andy,
Are you going to be plugged to shore power (at least 20 amps) during storage? If so, there are a number of posts here in connection with this issue. Installing a trickle charger for the starting batteries if shore power is available? Keeping the coach batteries charged? The fan motor for the furnace eats a lot of battery power, and if not connected to shore power the house batteries will need to be kept charged. If you don't have shore power, does your generator have an auto start feature? Can you visit the coach while in storage often? You should be in a position to inspect the coach while in storage often (at least once a week) if the batteries are being discharged by any coach systems, including those that take the power from the starting batteries.

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