EPDM Coatings
rvupgradestore.com Composet Products Custom Yacht Interiors

Author Topic: correct wiring 12 volt polarity  (Read 25136 times)

1275gtsport

  • ---
  • Posts: 479
correct wiring 12 volt polarity
« on: May 28, 2009, 07:45:53 AM »
OK I am now starting to wire the old 74 rockwood. I tore everything out and am now back to installing lights and cabinet doors. the fridge that came with the rv had been "hotwired" so as not to need 12 volt. the PO wanted to power a dvd player or something from the source. anyway I am not sure I trust the fridge too much so I have purchased a newer (1979) fridge. I wish to test on ac power before I install it in the MH. as I have to remove both driving seats in order to get the fridge inside. (it is about a half inch too wide to come through the RV door)

yes yes getting to the question. would it be safe to say the standard in rv wiring is that the black is HOT and the White is Ground? I don't want to reverse the polarity and kill my "new" fridge.
1977 GMC 26 foot Palm Beach
1976 Austin Mini

seilerbird

  • Guest
Re: correct wiring 12 volt polarity
« Reply #1 on: May 28, 2009, 08:33:55 AM »
For 110 volts the industry standard is black is hot and white is neutral and green is ground. For 12 volts the industry standard is red is hot and black is ground.

John Canfield

  • Forum Staff
  • ---
  • *
  • Posts: 11942
    • Jane and John's Internet Home
Re: correct wiring 12 volt polarity
« Reply #2 on: May 28, 2009, 08:48:09 AM »
Tom is correct about red/black being +/- as a general standard except my Horizon (Winnebago Industries) uses yellow for positive and white for negative.  Haven't figured that one out yet  ??? ::)
--John
2005 Horizon 40AD, 2006 Jeep Rubicon Unlimited
Our Horizon projects
Our weather

geodrake

  • Forum Staff
  • ---
  • *
  • Posts: 5744
Re: correct wiring 12 volt polarity
« Reply #3 on: May 28, 2009, 08:50:28 AM »
Just curious, if it is so much trouble getting the fridg in why use a 30 year old frig?  Sounds to me like you may be doing it again soon!
« Last Edit: May 28, 2009, 08:54:56 AM by geodrake »
George Drake

1275gtsport

  • ---
  • Posts: 479
Re: correct wiring 12 volt polarity
« Reply #4 on: May 28, 2009, 09:10:23 AM »
Thanks for the replies.

one the wires in the rv for 12 volt are a red jacket with black and white wires inside. it really won't matter what the color is as I haven't hooked anything to the battery yet. I just want to make sure my TEDCO fridge uses black as postive.

and geodrake - up front cost this years budget is very tight. yes in the long run we may have to replace the unit. however I have found online a couple of places that sell the coils for these types of fridges. and really all the fridges are is insulated boxes with coils on the back. not alot of moving parts. the coils on the "30 year old fridge are clean and nearly rust free. the one on the older fridge are very rusty. from what I understand about how the absorption fridge works is that as long as the tubes in the coil don't leak it will work for ever. the amount of work to get one fridge out and the other in is the reason I want to bench test the "new" fridge.
1977 GMC 26 foot Palm Beach
1976 Austin Mini

seilerbird

  • Guest
Re: correct wiring 12 volt polarity
« Reply #5 on: May 28, 2009, 09:20:20 AM »
Tom is correct about red/black being +/- as a general standard except my Horizon (Winnebago Industries) uses yellow for positive and white for negative.  Haven't figured that one out yet  ??? ::)

I am just dying to put in a comment about where it might have been wired but I will bite my tongue.

Ned

  • Former Staff
  • ---
  • Posts: 25574
  • Ned and Lorna are former full time RVers
    • Have you seen Rolling Stock?
Re: correct wiring 12 volt polarity
« Reply #6 on: May 28, 2009, 09:38:29 AM »
In an RV, I would assume nothing and use a voltmeter to determine the polarity of any DC wiring.

AC uses white for neutral, green for ground, as Tom says, but the hot can be almost any other color, typically black or red.  I've even seen blue wire used for hot leads.
-- Ned -- Fulltimer 1997-2013
1997 Holiday Rambler Endeavor LE
2007 GMC Canyon

Gary RV_Wizard

  • Forum Staff
  • ---
  • *
  • Posts: 61059
  • RVer Emeritus
Re: correct wiring 12 volt polarity
« Reply #7 on: May 28, 2009, 09:57:49 AM »
And there is no "industry standard" for 12v color coding, so a meter is the only way to go.My coach uses red for 12v+ and black for 12v negative.

Is the wiring you are referring to on the Tedco fridge 120vac or 12v? Newer fridges use both 12v and 120vac, even whn in AC mode. The 12v powers the circuit board, display lights, etc. That way the same power source works for propane or electric modes. If 120vac, then yes black is hot and white is neutral. If 12v, its pure guesswork.
Gary
--------------
Gary Brinck
Summers: Black Mountain, NC
Home: Ocala National Forest, FL

Ron

  • Former Staff
  • ---
  • Posts: 18087
Re: correct wiring 12 volt polarity
« Reply #8 on: May 28, 2009, 10:05:53 AM »
Very good advice Ned.  One never knows what has been done incorrectly previously.  I think you will find there is an industry standard for DC wiring which is red for POS black for NEG is is just some use what ever color is less cost. ;D
Ron & Sam-home is where we park it. Currently located   HERE

Fred G.

  • ---
  • Posts: 373
  • 1988 Winnie Elandan
Re: correct wiring 12 volt polarity
« Reply #9 on: May 28, 2009, 10:06:26 AM »
In an RV, I would assume nothing and use a voltmeter to determine the polarity of any DC wiring.

AC uses white for neutral, green for ground, as Tom says, but the hot can be almost any other color, typically black or red.  I've even seen blue wire used for hot leads.

I would second that since my elandan uses green for (+) and Purple for (-) all around the coach. I found out with a multimeter.
I rather die on my feet than live on my knees. (Emiliano Zapata)

Ron

  • Former Staff
  • ---
  • Posts: 18087
Re: correct wiring 12 volt polarity
« Reply #10 on: May 28, 2009, 10:27:42 AM »
I would second that since my elandan uses green for (+) and Purple for (-) all around the coach. I found out with a multimeter.

Maybe green and purple colored wire was less expensive or the installer was color blind. ;D ;D ;D ;)  This is why Ned recommended using a multimeter to confirm polarity.
Ron & Sam-home is where we park it. Currently located   HERE

1275gtsport

  • ---
  • Posts: 479
Re: correct wiring 12 volt polarity
« Reply #11 on: May 28, 2009, 10:45:38 AM »
ok so what your telling me is that short of pulling the fridge apart to see where the white or black wires connect there ain't no way to know?

and yes this unit needs the 12 volt power to run the control board there is no lights on the panel just a couple of knobs for gas and electric temp controls. it uses separate controls for gas or electric. there is a switch for dc/ac operation.

basically when I plug it in to 120 volt on the garage floor nothing happens. so from that I guess I need 12 volt power to turn the control board on. or the whole unit is crap.

think of it this way: Fridge on garage floor
12 volt battery beside fridge.
which wire do I connect to positive?? the white wire on the back of the fridge or the black wire on the back of the fridge?

the owners manual for the fridge has no diagram.
1977 GMC 26 foot Palm Beach
1976 Austin Mini

John From Detroit

  • ---
  • Posts: 19804
  • ^My New Home^
    • Diabetics Forum
Re: correct wiring 12 volt polarity
« Reply #12 on: May 28, 2009, 11:05:24 AM »
I support the "Get a meter and measure" suggestion.. The reason is this.

I'm cross trained in electrical and electronics.

As someone up-thread said..  IN Electrical (120/240 and more) Black is hot, white is neutral, which is bonded to ground at the service box (first box past the meter)

IN Electonics, including automotive, Black is ground, as it should be (Ok, that's a :) )

Most RV's are wired by electricans, not electronics techincians like me

So I see a lot of white wires on the ground bus in my 12 volt panel

So measure, just to be sure

And on the battery,  Paint or nail polish the wires hooked to the POSITIVE Terminal RED, don't be afraid to overpaint the battery itself

Black on the Negative end of  the battery bank as well

That way if you ever have to re-connect... You will know which wire goes where
Nothing adds excitement like something that is none of your business
My Home is where I park it.

bross

  • ---
  • Posts: 319
Re: correct wiring 12 volt polarity
« Reply #13 on: May 28, 2009, 01:15:34 PM »

which wire do I connect to positive?? the white wire on the back of the fridge or the black wire on the back of the fridge?

I would connect an ohm meter to the refrigerator frame and test both wires. The wire that's connected to the frame would be my negative.
Bill & Doris
Winnebago Adventurer 38Q

Gary RV_Wizard

  • Forum Staff
  • ---
  • *
  • Posts: 61059
  • RVer Emeritus
Re: correct wiring 12 volt polarity
« Reply #14 on: May 28, 2009, 05:32:42 PM »
Usually the fridge control board just has a terminal rather than a dangling wire and the terminal is marked + or - or POS  or GRD. And the hot terminal should lead directly to a fuse on the board. But you are talking about an old timer here and maybe they weren't so fussy back then...

Bross' idea about checking for a chassis ground is a good one. Hopefully that will show which one is NOT the hot lead.
Gary
--------------
Gary Brinck
Summers: Black Mountain, NC
Home: Ocala National Forest, FL

SCVJeff

  • ---
  • Posts: 1075
Re: correct wiring 12 volt polarity
« Reply #15 on: May 28, 2009, 08:13:25 PM »
Ditto on the meter. Winne uses White and Yellow all over the place (at least it's a standard), but way back in the 70's these things were made one-at-a-time, and even my 84' Pace had some flipped colors running around @ 12V.
_______________________________
Jeff - WA6EQU
Santa Clarita, CA.
'06 Itasca Meridian 34H, CAT C7/350

1275gtsport

  • ---
  • Posts: 479
Re: correct wiring 12 volt polarity
« Reply #16 on: June 04, 2009, 05:52:29 AM »
would it be safe to say regardless of color that the "hot" wire in the pair is marked in some way? either with writing or a ridge alone the length? would that at least be a standard? I have not had time to pull the panel off the front to see where the 12 volt power cables connect (which also power the "control board")

I am going to pull it apart today to be sure.
1977 GMC 26 foot Palm Beach
1976 Austin Mini

Jim Godward

  • ---
  • Posts: 5757
Re: correct wiring 12 volt polarity
« Reply #17 on: June 04, 2009, 03:36:24 PM »
I would assume NOHTHING on an RV that old.  You have no idea who may have been into the wiring and thus things happen when others do things.  

I can not even be sure on my MH and I have owned it since it was made.  The factory did some "interesting" things.
Jim
Jim & Pat Godward
AC7PO & KD7ZDM
Hillsboro, Oregon

carson

  • ---
  • Posts: 4925
  • memories of yore
Re: correct wiring 12 volt polarity
« Reply #18 on: June 04, 2009, 03:43:39 PM »
Jim,, how would you like buy the RV presently owned by John..JFD.?

Over the years I have read about things that John has done to his baby. I wonder if everything was documented. I suppose that happens a lot in used Rv's. Be aware...

No offense, John. Just an observation.

What say John?

carson FL

Carson, 
 West Central Florida
Ex RV'er. (1995 Winnebago Adventurer)
2007 Buick Rendezvous, SUV / CROSSOVER

...Logic works like a charm...

1275gtsport

  • ---
  • Posts: 479
Re: correct wiring 12 volt polarity
« Reply #19 on: June 04, 2009, 07:57:25 PM »
I would assume NOHTHING on an RV that old.  You have no idea who may have been into the wiring and thus things happen when others do things.  

I can not even be sure on my MH and I have owned it since it was made.  The factory did some "interesting" things.

Yes I agree that you can not trust what had been done. that is why I am re-wiring everything. in this rig it will be labeled. Black = hot and white will be ground. In the "house" anyway. the Dodge will also be wired correctly as in red to positive.

so what I gather is that there is no way to tell if the manufacturer of the fridge followed any kind of convention at all?

it looks like a lot of work to get the panel out to see if there is anything written on the control board. the propane lines go to the panel and it must be removed out the rear of the fridge which means it all has to come apart. and the 12 volt power wires do NOT ground to the case of the fridge.
1977 GMC 26 foot Palm Beach
1976 Austin Mini

Mike and Sherrie in VA

  • ---
  • Posts: 278
Re: correct wiring 12 volt polarity
« Reply #20 on: June 04, 2009, 08:10:19 PM »
I would connect an ohm meter to the refrigerator frame and test both wires. The wire that's connected to the frame would be my negative.

As far as testing the current configuration, I think bross summed it up pretty well.  See the above quote...  The wire connected to the frame should read 0 (or very close to 0) ohms, whereas the positive wire would read probably an open circuit (or almost inifinite resistance, as if you had not connected the meter at all).
1999 Fleetwood Southwind Storm 30H

1275gtsport

  • ---
  • Posts: 479
Re: correct wiring 12 volt polarity
« Reply #21 on: June 18, 2009, 09:15:28 AM »
Just to update for anybody that was watching this thread. I reverse engineered the 12 system on the fridge itself. I found a reference to testing the electrical coils themselves and the fellow explained how to "hot wire" the coils (he was checking to see if the control board was dead) so on my fridge nothing is grounded to the frame of the fridge. but by finding the ground and power wires leading to the 12 volt coil I was able to determine which unmarked white wire was power and which was ground. good thing because I would have wired it wrong! the ohm meter never lies! you just have to measure the right thing!

Thanks for all the help.
1977 GMC 26 foot Palm Beach
1976 Austin Mini

 

Hosted by Over The Network