RV.Net Open Roads Forum: Tech Issues: RV "Hot Skin" and GFCI?

RV Blog

  |  

RV Sales

  |  

Campgrounds

  |  

RV Parks

  |  

RV Club

  |  

RV Buyers Guide

  |  

Roadside Assistance

  |  

Extended Service Plan

  |  

RV Travel Assistance

  |  

RV Credit Card

  |  

RV Loans

Open Roads Forum Already a member? Login here.   If not, Register Today!  |  Help

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

Search:   Advanced Search

Search only in Tech Issues

Open Roads Forum  >  Tech Issues

 > RV "Hot Skin" and GFCI?

Reply to Topic  |  Subscribe  |  Print Topic  |  Post New Topic  | 
Page of 5  
Prev  |  Next
Sponsored By:
MEXICOWANDERER

las peñas, michoacan, mexico

Senior Member

Joined: 06/01/2007

View Profile


Offline
Posted: 08/15/17 01:01pm Link  |  Quote  |  Print  |  Notify Moderator

There is something FAR FAR more dangerous than you touching a rig with hot skin...

It's the DW touching your rig with hot skin.

tim.rohrer

USA

New Member

Joined: 10/13/2016

View Profile


Offline
Posted: 08/16/17 09:28pm Link  |  Quote  |  Print  |  Notify Moderator

Yesterday, I reintroduced the open ground in a controlled manner and conducted more than 47 tests with different configurations. I found about 56V on the frame when the main breaker and circuit breakers were on. When the main/circuit breakers were off, voltage on the frame was 19V.

Today I confirmed the EMS is faulty, as is the inverter. This was done through a series of tests and in coordination with the inverter's distributor. They have both been removed from my electrical system. The original service feed has been tied back into the distribution center.

Tonight I reintroduced the open ground and took voltage readings from the frame (BTW, I'm using the nearby water pipe as the ground). With the main breaker in the distribution center off, voltage was 3V. The voltage went up to 24V when the main breaker in the distribution center was turned on.

Because the EMS and inverter are out of the picture, I figure the first source of leakage has to be in the service feed, or in the distribution center. The latter makes sense to be because of the variations that occur when individual breakers are turned off.

I'm trying to figure out to test next. One thought is that I could remove from the RV's frame the bare ground wire coming from the distribution center. Then I'd take voltage reading on that wire to determine if anything is coming from the distribution center. Am I correct?

How can I test the distribution center? All the breakers seem solid.

Thanks.

Tim

road-runner

Oregon

Senior Member

Joined: 05/03/2015

View Profile


Offline
Posted: 08/16/17 10:04pm Link  |  Quote  |  Print  |  Notify Moderator

Are you trying to get the open frame voltage to be zero? If you take just an unconnected 100' coil of romex and energize it, you'll measure ~60 volts from the ground wire to either side with a high impedance meter. When the ungrounded frame voltage is close to zero, that IMO indicates neutral-to-ground leakage. Not necessarily a bad thing, just one of those "it is what it is" situations. I've found the power converter to be the worst leakage culprit. Could vary model-to-model of course.


2009 Fleetwood Icon

Harvard

51.6N 114.7W

Senior Member

Joined: 12/24/2005

View Profile



Posted: 08/16/17 10:09pm Link  |  Quote  |  Print  |  Notify Moderator

tim.rohrer wrote:

Yesterday, I reintroduced the open ground in a controlled manner and conducted more than 47 tests with different configurations. I found about 56V on the frame when the main breaker and circuit breakers were on. When the main/circuit breakers were off, voltage on the frame was 19V.

Today I confirmed the EMS is faulty, as is the inverter. This was done through a series of tests and in coordination with the inverter's distributor. They have both been removed from my electrical system. The original service feed has been tied back into the distribution center.

Tonight I reintroduced the open ground and took voltage readings from the frame (BTW, I'm using the nearby water pipe as the ground). With the main breaker in the distribution center off, voltage was 3V. The voltage went up to 24V when the main breaker in the distribution center was turned on.

Because the EMS and inverter are out of the picture, I figure the first source of leakage has to be in the service feed, or in the distribution center. The latter makes sense to be because of the variations that occur when individual breakers are turned off.

I'm trying to figure out to test next. One thought is that I could remove from the RV's frame the bare ground wire coming from the distribution center. Then I'd take voltage reading on that wire to determine if anything is coming from the distribution center. Am I correct?

How can I test the distribution center? All the breakers seem solid.

Thanks.

Tim


In your present configuration and from the information given, you do not have a problem. You are chasing voltages due to stray capacitance.

MEXICOWANDERER

las peñas, michoacan, mexico

Senior Member

Joined: 06/01/2007

View Profile


Offline
Posted: 08/16/17 11:20pm Link  |  Quote  |  Print  |  Notify Moderator

Yup. Do yourself a favor. Set you DMM on AC amps, stick one lead in the earth, and touch the other lead to the trailer. What do you see*? Always better with an analog meter but a digital will have to do. Power supplies like the Meanwell and Megawatt are famous for absolutely needing an earth ground for safety. The Bipolar transistors are to blame.

Regardless of the cause, cure the effect and maintain integrity for safety. On both sides I always look for unintentional bond of neutral to ground.

tim.rohrer

USA

New Member

Joined: 10/13/2016

View Profile


Offline
Posted: 08/17/17 10:29am Link  |  Quote  |  Print  |  Notify Moderator

Thanks, y'all. I'm still learning, and that is good.

I think I've got the concept of neutral-to-gound bond understood. I've also read that <2V across the N-G is considered normal, and that NEC guidance allows a bit more (up to 5%).

I am a little confused on how I have 3V with the RV's main breaker off, and with the main breaker on, it jumps to 24V. Unless I'm misunderstanding something, 24V is no where near the allowable amount by code.

@mexicowanderer In an open ground condition, but with all other parts of the circuit in proper condition, what should I see when I measure current from the frame to the established earth ground?

Thanks.

enblethen

Moses Lake, WA

Senior Member

Joined: 01/05/2005

View Profile






Posted: 08/17/17 11:03am Link  |  Quote  |  Print  |  Notify Moderator

It is induced current in the shore power cord.


Bud
USAF Retired
Suzuki XL7 pushing Pace Arrow

2003 Chev Ice Road Tracker


road-runner

Oregon

Senior Member

Joined: 05/03/2015

View Profile


Offline
Posted: 08/17/17 11:14am Link  |  Quote  |  Print  |  Notify Moderator

I've measured power converter leakage to ground in the 2 to 3 ma. range. Ideally, it would be balanced hot-to-ground and neutral-to-ground leakage. An easy test if you're wondering about leakage to ground is to plug the RV into a known working GFCI outlet, and operate whatever devices you can without overloading the GFCI circuit. If the hot-to-ground leakage is over 5 ma. the GFCI should trip. Neutral-to-ground leakage tripping isn't as precise, but anything significant should trip the GFCI.

tim.rohrer

USA

New Member

Joined: 10/13/2016

View Profile


Offline
Posted: 08/17/17 11:16am Link  |  Quote  |  Print  |  Notify Moderator

road-runner wrote:

I've measured power converter leakage to ground in the 2 to 3 ma. range. Ideally, it would be balanced hot-to-ground and neutral-to-ground leakage. An easy test if you're wondering about leakage to ground is to plug the RV into a known working GFCI outlet, and operate whatever devices you can without overloading the GFCI circuit. If the hot-to-ground leakage is over 5 ma. the GFCI should trip. Neutral-to-ground leakage tripping isn't as precise, but anything significant should trip the GFCI.


Should I do this test with the ground at the pedestal in place, or broken?

Harvard

51.6N 114.7W

Senior Member

Joined: 12/24/2005

View Profile



Posted: 08/17/17 12:00pm Link  |  Quote  |  Print  |  Notify Moderator

The < 2 V applies to when the Ground Wire to the Pedestal is INTACT, all voltage numbers with a floating ground are random numbers.

Reply to Topic  |  Subscribe  |  Print Topic  |  Post New Topic  | 
Page of 5  
Prev  |  Next

Open Roads Forum  >  Tech Issues

 > RV "Hot Skin" and GFCI?
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:

© 2017 CWI, Inc. © 2017 Good Sam Enterprises, LLC. All Rights Reserved. | Terms of Use | PRIVACY POLICY | YOUR PRIVACY RIGHTS