Generator neutral-ground bonding

[BB_TX]

I inadvertently got caught up in a long discussion on another forum about RV generators and bonding neutral to ground. The OP mentioned his Alliance RV showed open ground when on factory installed generator or inverter because neutral was not bonded to ground and asked if that was normal. He said he could not get a clear answer from alliance.

I never had a generator or solar, but with my electrical background I said the GFCI outlets would not function properly without a ground path back to the power source. Several immediately jumped in saying I was wrong because NEC allows GFCI outlets installed in older homes that do not have grounds to the outlets. I tried to explain that old homes and RVs were apples and oranges and can’t be compared.

So this lead to further discussions and me doing quite a bit of research and finding NEC actually has a lengthy section (Article 551) on RV power systems including generators. And has a specific requirement for providing “an effective ground-fault” circuit. OSHA has something similar. And someone else posted a link supporting bonding. The ones who disagreed apparently left the discussion, so I don’t know if I convinced them or simply outlasted them.

So. (Sorry for the long post). My question for you who have generators, both portable and factory installed, is does your generator have neutral to ground bonding? What does Keystone do?

Here is the long discussion if you care to read it.
https://www.rv.net/forum/index.cfm/f...pging/1/page/1

[Carl n Susan]

I run off either a Honda 2000i or a HF 3500. Neither is grounded. I have a couple of bonded neutral plugs but I usually forget to use them. My Splendide doesn't like either generator and does weird things. I just turn off the breaker., But all my GFCIs work off the generators regardless of the presence or lack on a bonded neutral plug.

Also, I don't use my EMS when running off my generators.

[BB_TX]

I should have said “not trip properly” rather the “not function properly”.

[BB_TX]

Another consequence of not bonding would be that if HOT somehow got shorted to RV frame the associated circuit breaker would not trip since with open ground there would be no return path to carry the current. That would leave the frame hot 120 vac.

[Bourbon County]

I believe the GFCI receptacle would function properly while running on generator. The GFCI works by measuring the current flow in both the hot and neutral, if the difference is >5 milliamps, it trips, doesn't need a ground reference to measure these currents. The assumption is current is leaking to ground maybe through your body. They are strictly for human protection.

It's understandable that any kind of power protection device would not work, nor would a plug in GFCI tester. The test button on the receptacle should work if you want to test.

That is an interesting point about current leakage to the RV chassis. The truth is unless you're touching the frame or maybe the hitch, there aren't that many conductive surfaces you could touch. The water lines are PEX, drains are ABS. How about those folks pulling Airstreams though!

[mlh]

Should we have a ground wire from the ground post on the generator to the camper frame if we already have a bonded ground? I think the answer will be yes. I have wired my house and three phase shop but that doesn’t mean I know anything about electricity except ever pee on an electric fence which I did in the dark one time. Yep once was enough to teach me all I really needed to know.
Lynwood

[C&P RV]

I have a 2022. It's my understanding -- understanding only -- that the transfer switch won't engage unless the RV is neutral - ground bonded and the power source, including generator, is also bonded. My Southwire SurgeGuard 34950 will also indicate a fault if the trailer isn't bonded (open neutral shows on the display). I keep a self-made bonding plug in my Predator 3500 generator and actually use the SurgeGuard when I'm running on generator power as an added level of safety for inadvertent brownouts in case the generator quits or runs out of gas.

[MandK]

I made up a grounding plug for my little 2500 Champion. Everything seems to work as it should, but I just use it to run the charger/converter for the very rare occasions that we are overnighting somewhere without power or when there is a power outage, which seems to be more often than it should be at NY State parks.

[BB_TX]

Originally Posted by Bourbon County

I believe the GFCI receptacle would function properly while running on generator. The GFCI works by measuring the current flow in both the hot and neutral, if the difference is >5 milliamps, it trips, doesn't need a ground reference to measure these currents. The assumption is current is leaking to ground maybe through your body. They are strictly for human protection.
…….

And that was a large part of the discussion. But for there to be a difference between the amount of current flowing in the hot pin and the amount of current flowing back out the neutral pin requires that the difference has to have “leaked” out of the circuit between the two. But current can’t leak out without a path back to the source, in this case the generator. And with no ground there is no path for that errant ground fault current to get back. So a difference can’t exist. Current must have a closed path back to the initial source to flow.

[BB_TX]

Originally Posted by mlh

Should we have a ground wire from the ground post on the generator to the camper frame if we already have a bonded ground? I think the answer will be yes. I have wired my house and three phase shop but that doesn’t mean I know anything about electricity except ever pee on an electric fence which I did in the dark one time. Yep once was enough to teach me all I really needed to know.
Lynwood

If the NEU and GND are bonded at the source (generator in this case) then frame is connected to NEU thru the ground wire in the power cord when plugged into the generator. No extra wire needed.

[BB_TX]

Here is a good description on why NEU-GND bonding is necessary to make GFCIs trip on a ground fault and to keep the “hot frame” condition I mentioned above from occurring.

https://www.rvtravel.com/rv-electric...ng_generators/

[Daryles]

My Harbor Freight Predator 2000W generator does not have a neutral to ground bond.
I do not have a N-G bonding plug.
Everything works fine.
Spent 10 days dry camping at Moab.
I MAY have a "hot skin" condition on generator/solar power. OR it could have been the dry desert air and static electricity. I will be investigating thoroughly in a few weeks when we are dry camping again.
No "hot skin" (or static electricity) when on Shore power.

[jeffba]

Originally Posted by Daryles

My Harbor Freight Predator 2000W generator does not have a neutral to ground bond.
I do not have a N-G bonding plug.
Everything works fine.
Spent 10 days dry camping at Moab.
I MAY have a "hot skin" condition on generator/solar power. OR it could have been the dry desert air and static electricity. I will be investigating thoroughly in a few weeks when we are dry camping again.
No "hot skin" (or static electricity) when on Shore power.

Hot Skin on genny and not on Shore power. You are prime for a Lynwood electric fence experience.

[mlh]

Originally Posted by jeffba

Hot Skin on genny and not on Shore power. You are prime for a Lynwood electric fence experience.

Well not quite. Electric fence is low amp 20,000 voltage camper is 120 but it will still get your attention.
Lynwood

[BB_TX]

Saw an interesting video of 4 fools standing side by side next to an electric fence. The first 3 were standing on plastic buckets. The last one standing on the ground. The first person grabbed the electric fence and nothing happened. That person held hands with the second person and nothing happened. That person held hands with the third person and nothing happened. As soon as that person touched hands with the fool on the ground they all got shocked.

But that describes the open ground issue. The electric fence controller has a positive terminal connected to the wire and a negative terminal connected to a rod driven into the ground for earth ground. If whatever touches the live wire is not touching the ground source, then nothing happens.

[BB_TX]

I am still curious about those who have permanent generators factory installed or dealer installed. Do those have an N-G bond?

[mlh]

Several years ago I talked to a guy who worked on 760,000 volt transmission lines. He worked from a helicopter. As well as I remember he said he would hook a grounding line from the helicopter to the line and I think he was grounded to the chopper. Then he could work on the bare line without any protection. He did say he had placed on him without any pigment. I don’t know if that came from the high voltage or not. The electricity had no place to go so he was safe.
Lynwood

[rohrmann]

Working on any voltage like that isn’t being grounded but having the line and the helicopter connected with the jumper brings everything to the same potential. This is just like a bird landing on the line. Lineman can also work out of an insulated lift bare handed on high voltages too. I never got to do that but did work on high voltages with rubber gloves.

[BB_TX]

Current passing thru a wire creates an electromagnetic field (EMF) around that wire. The greater the current the stronger the field. And that EMF can create a voltage potential on any adjacent metal close enough. That is the working principle of a transformer. A basic transformer has two wire windings that are not electrically connected to each other. Applying a voltage to the primary winding causes current to flow thru that winding. That current creates an EMF around that wire winding. That EMF causes a potential voltage on the secondary winding. And if something is connected to that secondary winding, current will flow thru it.

I suspect a helicopter that near a high voltage line carrying a lot of current could actually develop a potential voltage on the metal frame of the helicopter. Connecting a wire between the helicopter and the power line ensures that potential voltage doesn’t develop.

[mlh]

Originally Posted by BB_TX

Current passing thru a wire creates an electromagnetic field (EMF) around that wire. The greater the current the stronger the field. And that EMF can create a voltage potential on any adjacent metal close enough. That is the working principle of a transformer. A basic transformer has two wire windings that are not electrically connected to each other. Applying a voltage to the primary winding causes current to flow thru that winding. That current creates an EMF around that wire winding. That EMF causes a potential voltage on the secondary winding. And if something is connected to that secondary winding, current will flow thru it.

I suspect a helicopter that near a high voltage line carrying a lot of current could actually develop a potential voltage on the metal frame of the helicopter. Connecting a wire between the helicopter and the power line ensures that potential voltage doesn’t develop.

Thanks Bill. That sounds reasonable.
Lynwood