Open Ground

[CYCLEPATH]

Hello all. Just made the jump from my Lance camper, which I loved, to an Alliance Paradigm 310RL. It's a beautiful rig. The day after bringing it home, I was going over the electrical system. It has what they call the Super Solar Package.

When on inverter power, and onboard Onan generator power, I am showing an open ground on the outlet tester, in all the outlets I tested. On our 30amp home shore power, the outlets test normal. I have read where some say this is normal, others that it is not. Any hard core RV electrical guys out there with an opinion? I have a service call into Alliance, but have not heard back from them yet. Thank you all.

[BB_TX]

Mike134 wrote:


Be happy to explain why your wrong about GFIs needing a "ground reference" to work and trip.
They operate to save your life from an electric shock by constantly comparing the current flowing in the hot and neutral wires. If there is more than a 5-milliamp difference between the 2 wires it trip. They don't need any type of "refence to ground" they just monitor amperage in the hot and neutral wire to be sure they are within .005amps of each other.

I'm not your typical armchair expert (retired master electrician) What is your training in the electrical field if I may ask?

Note the last sentence in the first paragraph of "how do they work"
.
https://www.cpsc.gov/s3fs-public/099_0.pdf

I am well aware how they work. But if you have 5 amps flowing in the HOT pin and 5 amps minus 5 milliamps flowing back into NEU pin (5 ma imbalance), where did that lost 5 milliamps go? It can’t flow out into thin air. It can only flow back to the power source through some conductive path. Again, a very basic principle of electricity. Tell me where that conductive path is in an RV where there is no ground path back to the generator when the neutral and ground are not connected.

And I am a BSEE, registered professional engineer state of Texas (retired), and worked 35 years as a safety system design engineer. Thank you for asking.

[enblethen]

Get away from the GFI talk and get to basics of the electrical system. Bonding of the neutral and ground needs to be accomplished in accordance with NEC Article 250-92.

[Mike134]

Be happy to explain why your wrong about GFIs needing a "ground reference" to work and trip.
They operate to save your life from an electric shock by constantly comparing the current flowing in the hot and neutral wires. If there is more than a 5-milliamp difference between the 2 wires it trip. They don't need any type of "refence to ground" they just monitor amperage in the hot and neutral wire to be sure they are within .005amps of each other.

I'm not your typical armchair expert (retired master electrician) What is your training in the electrical field if I may ask?

Note the last sentence in the first paragraph of "how do they work"
.
https://www.cpsc.gov/s3fs-public/099_0.pdf

[BB_TX]

Apples and oranges.

In an old home without grounding, GFCI outlets will still trip because water and gas pipes buried underground provide an earth ground source to divert any ground fault current leakage around the GFCI outlet back to the power source to create the imbalance.

With an RV where the generator neutral and ground are not bonded and the RV and generator are not grounded to earth there is no path for any fault to leak current around the GFCI outlet. (If you know of a path please tell me.) That is why the National Electric Code section for RV generator power statement posted on page 1 of this discussion states the requirement for bonding and creating a ground-fault path. That is further supported by the OSHA statement on page 2. Basic principle of electricity is that a closed circuit is required for current flow.

If I am wrong please explain why.

[Mike134]

BB_TX wrote:
If you have an open ground, your GFCI outlets are not going to trip on a ground fault. They require an electrical path to the power source neutral-ground bond to trip. And if you should have a hot wire shorted to ground or RV frame it will not trip the circuit breaker. It will create a hot frame though. None of which are good conditions. .

This is incorrect. GFI outlets work just fine without a ground wire present.
In fact, the NEC allows you to replace old 2 wire outlets in old homes not having ground wires with 3 wire outlets provided you use a GFI outlet.
https://www.ecmweb.com/content/article/20896746/replacing-2wire-ungrounded-receptacles

[CYCLEPATH]

Too late. Just got off the phone with Alliance. He said it is normal, that is the way they wire the coach. Stated what is now becoming the obvious - not grounded to earth. He said since they wire it that way, IF there was a problem, it would be covered under warranty.
I'm not sure what I have learned from this whole thing, but I certainly climbed around that unit and traced a whole lot of wires. That was quite enlightening. Also installed a Renogy BT-2 on the solar controller while I was in there.
I appreciate the time you all took to send your replies. Very much. Thank you all.

[BB_TX]

When you call Alliance you might mention the statements in NEC and OSHA from my previous posts.

[CYCLEPATH]

Just got off the phone with a mechanic from Cummins/Onan. He says it is normal to have an open ground in an outlet when on gen power. He also said it was up to how Alliance installs it, as most folks have said He said since the coach itself isn't grounded to earth, you would have an open ground. I brought up the bonded plug. He said they do that on the smaller portable gens, but again it was up to Alliance, and how they wire it. I am now going to call Alliance. I'm leaning towards the this is normal category. Otherwise, it's a trip to the dealer. Thank you all.

[BB_TX]

Actually I think the responsibility falls on the RV manufacturer. Since the generator manufacturers do not always automatically bond neutral to ground leads me to think maybe there are applications where they would legitimately not be bonded. Don’t know. But if that is the case then proper installation would be the responsibility of the person/company installing it. Same with an inverter.

[CYCLEPATH]

Also, per the Onan Quick Start Guide -

Status of Neutral Conductor
Neutral conductor bonded to frame (NEUTRE MIS A LA MASSE AU CHASSIS) unless modified by or according to customer's requirements.

As of a point of interest, that was the only foreign language in the whole guide. I found the guide in the plastic wrap tucked in a crevice back behind one of the panels.

[CYCLEPATH]

I will call Cummins/Onan today. Having a heck of a time finding the transfer switch. Will try to trace the line from the gen. The shore power cord goes directly into the WatchDog, then heads for the panel. Also, the Renogy Inverter has a transfer switch function. All connections I have checked so far are tight. I don’t want to make a trip to the dealer if I don’t have to.
Is anyone else out there showing an open ground while on inverter or gen power? I appreciate the input.

[CA_Traveler]

ScottG wrote:
Alliance has no idea what you're talking about.

X2

[enblethen]

I doubt whether General RV will give an answer other than it is ok. They don't know either.
Cummins/ Onan would be a better place to get information about bonding of their units.

[ScottG]

Alliance has no idea what you're talking about.

[BB_TX]

The more I read the more I am sure that neutral and ground should be bonded on an RV generator. From
OSHA Fact Sheet on portable generators;

Bonding is the intentional connection between the grounded circuit conductor (neutral) and the grounding means for the generator, which includes the generator’s frame. Thus, effective bonding of the neutral conductor to the generator’s frame is also a concern for the safe use of the the equipment

Been interesting to pursue this for facts rather than internet “experts”, including myself. :B