New EMS shows Open Ground ?

[Chakara]

Hey guys - was hoping some of you could check my sanity.  Here at the house I have a 30A RV hookup next to the trailer.  I plug the trailer in via an 30/50 amp adapter.

I  just completed the install of the EMS-HW50C 50 amp hard wired system.  I plug in the rig and low and behold, the EMS show EC#2 - Open Ground.

Yikes!  How long have I had that problem?  

I did a bit of reading and busted out the old Fluke.  Here is what I get

Pedestal no load:

Hot to Ground:       123V
Hot to Neutral:        123V
Neutral to Ground:  0V

Input to EMS - no load:

L1 to Ground:         123V
L2 to Ground:         123V
L1 to Neutral:          123V
L2 to Neutral:          123V
Neutral to Ground:   0V

I'm not an electrician, but this all seems normal.  This is where I got a little brave (foolish?? 🙂 ) and flipped the bypass switch on the EMS.  Trailer lights up and everything works.  I put a little heater as a load and the only different measurement with a load on is:

Neutral to Ground:    1.3V

Again, I think that when you have a load you should read some voltage on that link so it still feels normal?

Before I call Progressive Ind. for an RMA - - can anyone who knows more about electricity confirm my finding?  Or am I stupid and my trailer is going to burst into flames 🙂

Thanks all!

-Kyle
???????

[2naEagle]

Good news. Thank you for the information.

[Chakara]

Hi everyone,

To close the loop on this I wanted to let you all know the outcome. New EMS arrived last week and I got them swapped out yesterday. I do not like working with heavy gauge wire - what a pain.

Good news - works as designed. Progressive Ind. support was great, good company from my perspective.


https://photos.app.goo.gl/WPWnQxC6MahXonR2A

[Bobbo]

CA Traveler wrote:

Harvard wrote:
I just realized this RV is a trailer and not a motorhome. It matters because any trailer jacks that touch earth ground are going to provide a parallel ground path to the wired GREEN ground wire. Safety wise this is NOT an issue BUT it may be interfering with the trouble shooting voltage readings IF the GREEN GROUND wire is OPEN and not grounding the trailer

I would disagree. ANY GROUND FAULT exceeding the standard safe limit of 5 ma is a safety issue waiting for a opportunity. The potential for animal or human significant shock should always be considered a issue IMHO.

Grounding the frame through the jacks, when the ground pin is inoperative, can only increase safety. It is when the frame is NOT grounded that the risk for a shock by grounding through a person is greatest.

The jacks in the post are not contributing to a ground fault, they are grounding the TT. The only way they could contribute to a problem, is if they MASK a lack of ground without providing enough of a ground themselves.

[CA_Traveler]

Good points. In the past I've recommended periodically plugging into a GFCI and checking various appliances with loads up to the CB rating.

Another ground that can be a factor when there is a problem is the ground in the cable coax system.

[Harvard]

CA Traveler wrote:

Harvard wrote:
I just realized this RV is a trailer and not a motorhome. It matters because any trailer jacks that touch earth ground are going to provide a parallel ground path to the wired GREEN ground wire. Safety wise this is NOT an issue BUT it may be interfering with the trouble shooting voltage readings IF the GREEN GROUND wire is OPEN and not grounding the trailer

I would disagree. ANY GROUND FAULT exceeding the standard safe limit of 5 ma is a safety issue waiting for a opportunity. The potential for animal or human significant shock should always be considered a issue IMHO.

Just to clarify the not so obvious:

The danger here is IF the GREEN GROUND WIRE to the service is NOT INTACT, the secondary (or parallel) paths to EARTH through jacks MAY mask (hide) the "Open Ground" defect making it appear all is normal. When in fact, the electrical return path through earth will not conduct current sufficent to blow a standard breaker (Not with standing if it is a GFCI breaker).

[Harvard]

CA Traveler wrote:

Harvard wrote:
The N to G voltage of 1.3VAC would be abnormal if there is very little current in the Neutral wire. So if there is little or no Neutral current then that 1.3 VAC N to G is likely the problem.

There are multiple circuits on the CG distribution center and those circuits contribute to the N to G voltage difference. Meanwhile your circuit can have 0A and show a 1.3V voltage difference.

So a 1.3V difference does not indicate a problem unless you know the entire circuit configuration.

BTW Trailers often have additional jacks touching the ground as welll as many MHs.

You are absolutely right if there are multiple services where the neutrals are daisy chained. In this case the OP has stated he has a 30Amp supply at his house. I have incorrectly assumed he has not daisy chained this service.

[CA_Traveler]

Harvard wrote:
I just realized this RV is a trailer and not a motorhome. It matters because any trailer jacks that touch earth ground are going to provide a parallel ground path to the wired GREEN ground wire. Safety wise this is NOT an issue BUT it may be interfering with the trouble shooting voltage readings IF the GREEN GROUND wire is OPEN and not grounding the trailer

I would disagree. ANY GROUND FAULT exceeding the standard safe limit of 5 ma is a safety issue waiting for a opportunity. The potential for animal or human significant shock should always be considered a issue IMHO.

[CA_Traveler]

Harvard wrote:
The N to G voltage of 1.3VAC would be abnormal if there is very little current in the Neutral wire. So if there is little or no Neutral current then that 1.3 VAC N to G is likely the problem.

There are multiple circuits on the CG distribution center and those circuits contribute to the N to G voltage difference. Meanwhile your circuit can have 0A and show a 1.3V voltage difference.

So a 1.3V difference does not indicate a problem unless you know the entire circuit configuration.

BTW Trailers often have additional jacks touching the ground as welll as many MHs.

[2naEagle]

Chakara wrote:
Thanks everyone. I went through the majority of these recommendations and worked with support over at Progressive. They are shipping out a new unit.

If it is a "weak" ground or neutral - I guess I'll find out after going through the pain of swapping it out 🙂

-Kyle

Looking forward to seeing how this turns out. Please keep us posted.

[Harvard]

I just realized this RV is a trailer and not a motorhome. It matters because any trailer jacks that touch earth ground are going to provide a parallel ground path to the wired GREEN ground wire. Safety wise this is NOT an issue BUT it may be interfering with the trouble shooting voltage readings IF the GREEN GROUND wire is OPEN and not grounding the trailer

[Chakara]

Thanks everyone. I went through the majority of these recommendations and worked with support over at Progressive. They are shipping out a new unit.

If it is a "weak" ground or neutral - I guess I'll find out after going through the pain of swapping it out 🙂

-Kyle

[Harvard]

Chakara wrote:
Ok - I thought those were normal readings - thank you for confirming that Harvard!

The EMS still shows E-2 and PE-2. E-2 implies the problem still exists.
I'll get in there and do some "wiggling" of my install to confirm everything is tight and consistent, but I'm really thinking I got a defective EMS here......

-Kyle

The N to G voltage of 1.3VAC would be abnormal if there is very little current in the Neutral wire. So if there is little or no Neutral current then that 1.3 VAC N to G is likely the problem.

Take a voltage reading from RV Chassis to humid Earth Soil. If it is also 1.3 VAC then you probably have an open ground.

[Matt_Colie]

Chakara,

I doubt that the EMS is defective, but it is more likely that you have a "soft" neutral or ground. This is a VERY common issue. Got to every place that you can access and make sure that the ground and neutral connections are clean and tight. (Might as well check all of them when you can.) With your connector stack, the problem could be anywhere.

Matt

[Bobbo]

That happened to me when I first got my EMS-HW30C in 2007. It turned out that the shore cable for my RV was wired into the electrical box without connecting the ground wire. The hot wire and the neutral wire were wire nutted to the trailer wiring, the ground wire was not. (It was not the Airstream I now have.) I found that by checking continuity between the ground wire pin on the shore power cable and the RV frame. There should have been continuity, but there wasn't.