Good Sam Club Open Roads Forum: Tech Issues: 12V receptacle polarity
Open Roads Forum Already a member? Login here.   If not, Register Today!  |  Help

Newest  |  Active  |  Popular  |  RVing FAQ Forum Rules  |  Forum Posting Help and Support  |  Contact  

Search:   Advanced Search

Search only in Tech Issues

Open Roads Forum  >  Tech Issues

 > 12V receptacle polarity

Reply to Topic  |  Subscribe  |  Print Topic  |  Post New Topic  | 
Page of 3  
Next
Janss

Sedona, AZ

Senior Member

Joined: 04/29/2010

View Profile



Good Sam RV Club Member

Offline
Posted: 05/02/19 08:28pm Link  |  Quote  |  Print  |  Notify Moderator

Just bought a 12v cord for CPAP machine use in RV. Instructions state "The Shielded DC Cord is intended for use on 12 volt positive hot electrical systems. These systems might also be referred to as negative ground."
Also:
"The connector end of the DC cord is constructed so that the outside of the barrel is ground and the inside of the barrel is positive."

So I used a multimeter to test the 12v outlet in my bedroom. (I know nothing about electrical stuff.) When I touched the red probe to the center plate at back of outlet and the black probe to the barrel wall of the outlet, the multimeter showed 13.71. Then I touched the black probe to center plate and red to barrel wall and multimeter showed -13.71.

So does this mean the outlet is "positive hot", as needed for this cord to work properly?


2002 Itasca Suncruiser 32V
2012 Suzuki Grand Vitara

rk911

Wheaton IL

Senior Member

Joined: 05/30/2004

View Profile



Good Sam RV Club Member

Offline
Posted: 05/02/19 08:31pm Link  |  Quote  |  Print  |  Notify Moderator

Janss wrote:

Just bought a 12v cord for CPAP machine use in RV. Instructions state "The Shielded DC Cord is intended for use on 12 volt positive hot electrical systems. These systems might also be referred to as negative ground."
Also:
"The connector end of the DC cord is constructed so that the outside of the barrel is ground and the inside of the barrel is positive."

So I used a multimeter to test the 12v outlet in my bedroom. (I know nothing about electrical stuff.) When I touched the red probe to the center plate at back of outlet and the black probe to the barrel wall of the outlet, the multimeter showed 13.71. Then I touched the black probe to center plate and red to barrel wall and multimeter showed -13.71.

So does this mean the outlet is "positive hot", as needed for this cord to work properly?


yes


'73,
rich, n9dko
Remember...if you don’t know where you’re going you're bound to end up somewhere else.
_________________________________
_________________________________
2016 Itasca Suncruiser 38Q
'46 Willys CJ2A
'03 Jeep Wrangler TJ
'10 Jeep Liberty KK



Bobbo

Wherever I park

Senior Member

Joined: 09/16/2007

View Profile



Good Sam RV Club Member

Offline
Posted: 05/02/19 08:46pm Link  |  Quote  |  Print  |  Notify Moderator

rk911 wrote:

Janss wrote:

Just bought a 12v cord for CPAP machine use in RV. Instructions state "The Shielded DC Cord is intended for use on 12 volt positive hot electrical systems. These systems might also be referred to as negative ground."
Also:
"The connector end of the DC cord is constructed so that the outside of the barrel is ground and the inside of the barrel is positive."

So I used a multimeter to test the 12v outlet in my bedroom. (I know nothing about electrical stuff.) When I touched the red probe to the center plate at back of outlet and the black probe to the barrel wall of the outlet, the multimeter showed 13.71. Then I touched the black probe to center plate and red to barrel wall and multimeter showed -13.71.

So does this mean the outlet is "positive hot", as needed for this cord to work properly?


yes

What he ^^^^^^^^^^^ said.


Bobbo, Linda and the furry kid (45 pound rescue)
2017 F-150 XLT 4x4 SuperCab w/Max Tow Package 3.5l EcoBoost V6
2017 Airstream Flying Cloud 23FB


cavie

Port Charlotte Fl/ Hindsdale MA

Senior Member

Joined: 04/28/2019

View Profile


Offline
Posted: 05/03/19 06:05am Link  |  Quote  |  Print  |  Notify Moderator

Negative hot went out with the 1949 Ford. Red is positive, Black is ground.


2011 Keystone Sprinter 323BHS. Retired Master Electrician. Retired Building Inspector.

All Motor Homes are RV's. All RV's are not Motor Homes.

wa8yxm

Wherever I happen to park

Senior Member

Joined: 07/04/2006

View Profile


Offline
Posted: 05/03/19 06:18am Link  |  Quote  |  Print  |  Notify Moderator

Janss wrote:



So does this mean the outlet is "positive hot", as needed for this cord to work properly?


Short answer YES.. Long answer YES IT IS.

I have a special device to do that (Somewhere) but. you are good to breath.


Home is where I park it.
Kenwood TS-2000 housed in a 2005 Damon Intruder 377


GordonThree

Northern Michigan

Senior Member

Joined: 05/19/2013

View Profile


Offline
Posted: 05/03/19 07:24am Link  |  Quote  |  Print  |  Notify Moderator

cavie wrote:

Negative hot went out with the 1949 Ford. Red is positive, Black is ground.


I'd urge a bit of caution on this statement. In my RV, it's often black is positive / hot and white is negative / ground, there is no red. Evidence i've seen of other RVs indicates a similar color scheme is used.


2013 KZ Sportsmen Classic 200, 20 ft TT
2017 Ram 2500 4x4, 6.4 HEMI, 4.10 / Auto

Sam Spade

North Central Florida

Senior Member

Joined: 11/05/2015

View Profile


Offline
Posted: 05/03/19 07:26am Link  |  Quote  |  Print  |  Notify Moderator

rk911 wrote:


yes


Add another YES.

Note: If you are boondocking, which is the only time that you really need 12 V for your CPAP, be sure that the humidity heater is OFF or turned down very low. It uses a lot of power.


'07 Damon Outlaw 3611
CanAm Spyder in the "trunk"

cavie

Port Charlotte Fl/ Hindsdale MA

Senior Member

Joined: 04/28/2019

View Profile


Offline
Posted: 05/03/19 07:55am Link  |  Quote  |  Print  |  Notify Moderator

GordonThree wrote:

cavie wrote:

Negative hot went out with the 1949 Ford. Red is positive, Black is ground.


I'd urge a bit of caution on this statement. In my RV, it's often black is positive / hot and white is negative / ground, there is no red. Evidence i've seen of other RVs indicates a similar color scheme is used.


As a master electrician I am very aware of electrical color coding.
White was not being discussed here. I was talking about the red and Black leads in the meter the OP was using.[emoticon]

Janss

Sedona, AZ

Senior Member

Joined: 04/29/2010

View Profile



Good Sam RV Club Member

Offline
Posted: 05/03/19 08:30am Link  |  Quote  |  Print  |  Notify Moderator

Thank you everyone! Now my spouse can sleep well while boondocking [emoticon]

YC 1

Yuba City Calif./ Auburndale Florida

Senior Member

Joined: 01/11/2005

View Profile



Good Sam RV Club Member

Offline
Posted: 05/03/19 03:56pm Link  |  Quote  |  Print  |  Notify Moderator

There were many positive ground trucks going into the early 70's.. It was very important to check them before installing two way radios. There were radios that had an internal plug to change them from negative to positive ground.

As mentioned, it is good to remember that the black wire of the RV is often the HOT wire and in todays units that is positive. Just don't mistake the black wire 12 volts for 110 volts AC.


H/R Endeavor 2008
2013 Ford Edge toad
Full Timers


Reply to Topic  |  Subscribe  |  Print Topic  |  Post New Topic  | 
Page of 3  
Next

Open Roads Forum  >  Tech Issues

 > 12V receptacle polarity
Search:   Advanced Search

Search only in Tech Issues


New posts No new posts
Closed, new posts Closed, no new posts
Moved, new posts Moved, no new posts

Adjust text size:

© 2019 CWI, Inc. © 2019 Good Sam Enterprises, LLC. All Rights Reserved. | Terms of Use | PRIVACY POLICY | YOUR PRIVACY RIGHTS