Ground-Fault if Honda is grounded or not

[Driver1]

Hi,
This past weekend, I hooked up our Honda eu2000i to recharge a bit. It set off our Surge Guard Digital Line Monitor with a ground fault warning. Steps taken with no better results:
1) Plugged the Digital Line Monitor into each of the 120v sockets directly on the Honda
2) Ran a copper wire from the ground connection point on the Honda to a steel tent peg in the ground.
3) Plugged the Digital Line Monitor into each of the 120v sockets directly on edgeman's Honda eu2000i

Next I plugged the Digital Line Monitor into a very old farm field outlet and it too showed the ground fault (OK, it's probably a bad monitor, right).

At this point, I just set the Digital Line Monitor aside and charged my batteries for a while (No damage apparent).

On returning home, I plugged the Digital Line Monitor into our trailer while hooked up to shore power. No ground fault - the monitor is working.

I've read 2air's thread started in 2006 about GFI troubles and see this is a different kind of situation. But I've been unable to find any threads dealing with generator ground faults.

Can anyone add insight to this situation?
Walt

[Over59]

I don't think they work with the generator. Remember the trailer has a floating ground setup and the generator isn't grounded either.

[Driver1]

Hi Over59,

Thanks for responding. See step 2 above, there is a ground connection point on the Honda & I did ground it. The Digital Line Monitor was plugged into the Honda directly (The trailer wiring was irrelevant at this point).

Why would a Digital Line Monitor not work with a generator which is supposed to put out clean, standard a/c power?

Walt

[azflycaster]

Yes you can add an external ground wire to the generator. Depending on soil makeup and moisture content, I doubt that a tent stake will do it. Most ground rods I have seen are in the six foot range. Why not set this up at home with the generator and run the ground wire to a water pipe (copper) that runs into the ground or a know ground line at your home's service entrance.

[Driver1]

Hi azflycaster,

Understood, I'll try that tomorrow AM and post back. Note: The stake was next to an irrigation ditch.

Walt

[bryanl]

A GFI problem is between neutral and ground, not to any earth or chassis ground.

The Honda does not bond the neutral and ground together and neither does (should) your trailer. Check the Honda manual for whether it is OK to tie the neutral to the chassis ground.

You do not need an earth ground with a portable genset nor does code require such. An earth ground is only required at the park service entrance which is where the neutral and ground are bonded. That is the only place they should be bonded. In portable service, some transfer switches will bond ground and neutral when they switch to genset power but it is generally not necessary.

The floating neutral common with genset power does cause some wiring protection devices some grief and a good device will cover this in its manual.

[Driver1]

Hi Leipper,

I'm trying to follow, but not sure I understand. When you say "The Honda does not bond the neutral and ground together...", does it mean that testing the outlets on the Honda should NOT show a ground fault (Regardless of whether the Honda is grounded or not)? This is right at the generator -- not hooked to the trailer (The trailer is out of the picture in this).

NOTE: We checked 2 Honda eu2000i's with the same ground fault result.

Is the Surge Guard Digital Line Monitor at fault and an inappropriate device to be using here?

Walt

[Driver1]

Hi again,

I grounded the generator to our house ground (Scraped to bright copper and held connection with a Vice-Grip). Then fired up the Honda and then plugged in the digital monitor. The result is the same ground fault.

Leipper, having the same result seems at least consistent with your statement "You do not need an earth ground with a portable genset...".

But, since the neutral and ground are not bonded together in the generator, I understand that I should NOT see a ground fault. Please correct me if I'm misunderstanding.

Does anyone else have a Honda eu2000i & Technology Research Corp. Digital Line Monitor model# AECM20020 (For specs try Technology Research Corporation / Select 'Other Products' / Select 'Digital Monitor -- Bought at Camping World) to try to duplicate what I'm seeing?

Thanks,
Walt

[bryanl]

Is the Surge Guard Digital Line Monitor at fault and an inappropriate device to be using here?

might be.

This is one of those simple complicated things that easily create confusion. There are lots of discussions about it, too.

On your electrical plug, 'ground' is a frame of reference that represents all of the things you can touch near the plug. 'Neutral' is the electrical path that is usually considered to be at the same electrical reference as ground but not locally attached to the ground. 'Hot' is considered to be the other side of the electrical circuit and at the greatest potential electrical difference from the ground.

What a GFI or ground fault interrupter device does is to match the current in the hot and the neutral to see if the match. If they don't it means current is getting out of where it needs to be and that implies a wiring fault that needs fixing.

A ground fault tester is probably checking to see if there are any leaks between the ground and neutral. It does this by looking at the resistance between neutral and ground. It expects a low resistance because proper wiring will have these two connected at the service entrance.

For grid attached systems, the frame of reference ground can be a real problem. Large distances and multiple attachment points and induced currents and such things keep power system engineers intellectually stimulated. These phenomena lead to the assumption that the frame of reference ground is a part of the circuit whether or not you want it to be so you define the rules for how it is connected to be able to control them. For RV's this assumption is not appropriate.

For RV's, the electrical power circuit is small and electrically isolated. It makes no difference which lead coming from the genset will be hot and which neutral. You define which is which by attaching one to the reference or frame ground, if you want (check the genset manual about this) but it isn't required by electrical codes. There is near zero risk of electrical current going through some other path than the neutral and hot leads in an RV genset situation so GFI type stuff isn't a concern of any weight.

Your test device, though, thinks it needs to find a low resistance between neutral and the reference frame ground because that is 'proper' wiring for grid connected power systems. If your RV system on genset doesn't bond these together, then the resistance between them will be high and the device will indicate a fault.

One way to tell if neutral and ground are bonded is to check the voltage between neutral and ground and hot and ground. In a proper grid wiring situation, the neutral to ground voltage will be zero and the hot to ground will be 120v. In an unbonded RV genset situation you'll probably find 60v between neutral to ground and between hot to ground. (that tells you there is a bit of coupling there but it is only visible because the meter has a high impedance).

If the manual says its OK, bond the neutral and ground together and then see what the line monitor thinks.

[Driver1]

Hi Leipper,

I did find this in the Honda owner's manual:
"Honda portable generators have a system ground that connects generator frame components to the ground terminals in the AC output receptacles. The system ground is not connected to the AC neutral wire. If the generator is tested by a receptacle tester, it will not show the same ground circuit condition as for a home receptacle."

This sounds highly consistent with what you're describing, Leipper.

On searching the whole PDF file for the words 'bond' and 'unbond', I found no references. I've also done a visual search of a hard copy of the shop manual and also found no reference. Neither seems to specify if it's OK to bond the neutral and ground together (I'll assume not OK for now).

I'll have to make another trip to the storage yard for my multitester to check for the 60v up and down. I'll report back once I know.

Regards,
Walt

[C Johnson]

HI Walt, We discovered that the power line at the rally site last weekend was indeed wired backward. So your montitor was working correctly there.

On another note, I charged my battery with Gary's generator on Monday and the ground fault light in my trailer was on but it was about half the brightness that it usually is. That goes along with what Byran is saying about there being just 60 V between the ground and the hot.

Thought you'd like to know.

[Over59]

Don't think you have a problem, which will make it very very hard to solve. The meter's design application is a standard AC circuit.
Bryan's explanation is great.

[bryanl]

bond means to electrically connect the wires together.

The Honda manual probably says it better than I can.

For a horror story about campground wiring, see Melting the plug which describes and links to an encounter with Oregon State Park electrical systems. It is amazing how many parks have wiring problems, sometimes even dangerous ones.

You might also be interested in Wiring your generator ground and genset grounding for more information and some links on the same blog.

[Driver1]

Hi Leipper,

When you used the word 'probably' in "In an unbonded RV genset situation you'll probably find 60v between neutral to ground and between hot to ground", was there some other possibliity in mind?

My readings a few minutes ago were 126v hot to neutral and 0v hot to ground.

Regards,
Walt

[Driver1]

Hi again,
I'm attaching a summary of what I've found and, with help from all of you posters, understand now. It's in a PDF to try to maintain the structure & graphic -- hope it works OK.

Some further thoughts:
1) I don't know if there are ground fault circuit interceptors in my 1998 Excella 1000, but from other reading I see they are in newer trailers. Do they trip when generator power is hooked up? If not, why not? Do they use some different mechanism vs. my line monitor's for detecting the fault? This thread, http://www.airforums.com/forums/f37/...s-21082-4.html , post #56 (From herrgirdner) seems to touch on this possibility.
2) Why not bond the neutral & ground at the generator so it would be like shore power hookups? Would that then require grounding of the generator?

Over59 - Your 1st response, "I don't think they work with the generator", seems to have been right ON! Yes, non-problems are especially difficult to solve. I suppose the real problem is my low level of understanding and wanting to understand better.

azflycaster - That tent peg probably was a bad idea in trying to set up a ground (Much too little contact).

C Johnson - Interesting to hear about the power line at the rally site. So you have a monitor of some sort with the "ground fault light in my trailer". Did any breakers trip?

Leipper - Thanks for the elaboration, your patience with me, and the focus on what's going on.

Regards to ALL,
Walt

[C Johnson]

Originally Posted by Driver1

C Johnson - Interesting to hear about the power line at the rally site. So you have a monitor of some sort with the "ground fault light in my trailer". Did any breakers trip?


Regards to ALL,
Walt

Hi Walt, Yes I have a monitor lamp in my trailer on the power control box which is separate from the breaker box. The lamp will be off if eveything is ok. On when hot and neutral are switched and dim when running off a genset. The power control box just decides whether I am running off the battery or the convertor. No I didn't have any breakers trip. I also have a central GFCI protecting all outlets on the trailer. They did not trip, but then there wasn't anything plugged into them either.

FWIW, I have seen the same monitor lamp on newer (newer than mine)trailers. Some on the outside near the cordset some on the inside.

[bryanl]

When you used the word 'probably'

being defensive: My 'tone' seems to offend some and all too often (it seems) they start playing one-upsmanship and go on a crusade to find fault or flaw. So the caveats, conditions, and other such stuff are for them.

You should see 0v between unconnected leads but stray capacitance and even your own body as an antenna can create points where voltages can be measured with a high impedance voltmeter. You can often test for live circuits with one of those neon bulb testers by holding one terminal in your fingers and probing the wiring with the other- Not enough current to feel but enough voltage to fire the neon.

Why not bond the neutral & ground at the generator so it would be like shore power hookups? Would that then require grounding of the generator?

Again, leave the earth ground out of it. That is not necessary. Don't confuse earth ground with the chassis ground or frame of reference.

As long as the genset has no problem with it, it is a good idea to connect the neutral and chassis or frame ground together if you are not connected to anything else.

If you are plugged into shore power and do not have a transfer switch, then the neutral and ground are connected at the shore power service point and ground checking things will work as intended.

If you are not connected to shore power but running AC off a genset, then you might connect the neutral and chassis ground yourself - if the genset manual says it is OK. I worry a bit about the inverter electronics but I'd guess they should handle this with no problem.

For gensets with plugs (e.g. the Honda 2000i) the neutral to chassis connection is not necessary except to make a test device happy. Even for wired in gensets like in my B-Van with a transfer switch, the test devices are left to complain (saves one pole on the switch, I guess). In either case, an earth ground is not needed either for the test device nor for any other reason.

[Motoman]

Originally Posted by Driver1

Hi again,

I grounded the generator to our house ground (Scraped to bright copper and held connection with a Vice-Grip). Then fired up the Honda and then plugged in the digital monitor. The result is the same ground fault.

Leipper, having the same result seems at least consistent with your statement "You do not need an earth ground with a portable genset...".

But, since the neutral and ground are not bonded together in the generator, I understand that I should NOT see a ground fault. Please correct me if I'm misunderstanding.

Does anyone else have a Honda eu2000i & Technology Research Corp. Digital Line Monitor model# AECM20020 (For specs try Technology Research Corporation / Select 'Other Products' / Select 'Digital Monitor -- Bought at Camping World) to try to duplicate what I'm seeing?

Thanks,
Walt

I couldn't tell if you got the answer you were looking for. A simple three light receptacle tester will always show a ground problem when plugged into a Honda generator, i.e. mine indicates an open ground. This is because the regulations for portable generators are not the same as the regulations for home and commercial wiring or fixed or permenant generators.

Page 17 of the EU2000i manual states "Honda portable generators have a system ground that connects generator frame components to the ground terminals in the AC output receptacles. The system ground is not connected to he AC neutral wire. If the generator is tested by a receptacle tester it will not show the same ground circuit condition as for a home receptacle."

The manual for the EU3000is has the same or similar language.

You will get the same results when you have your trailer hooked to the generator and test the receptacles in the trailer. It will show an open ground. There are advantages and disadvantages of this design but we can't change it. I do seem to remember that the Canadian regulations do require the neutral and ground to be bonded in portable generators but that is not the case in the US.

It may be a mute point, the main reason to use the receptacle tester is when you plug in at RV parks and other commercial power sources; if the hot wire is switched with the neutral and or ground you could get a shock touching the trailer and devices within or outside the trailer.

[Driver1]

Hi Leipper,

When you say "As long as the genset has no problem with it, it is a good idea to connect the neutral and chassis or frame ground together if you are not connected to anything else", I have to wonder why the generator manufacturers don't do it. It seems it would give them bragging rights to the effect that their product is the closest match to shore power. This seems like such a trivial change that I doubt the cost differential comes into play. Can you think of some other reason they just don't do it?

Alternatively, maybe there's an opportunity to make a plug adapter that would do the bonding right there at the plug. Hmmmm.

Regards,
Walt

[ROBERT CROSS]

This is how I corrected the false reading...

I got a 30amp pigtail,(short 30amp extension with one male end), open wires on other end.
Female 30amp replacement plug.
Install female end and add jumper between the green ground and white neutral terminals inside plug. Black is HOT. Terminals in plug should colored, black silver and green.

Plug your modified extension into the generator, and the coach power cord into that. The extension is not needed on shore power.

Now I am able to test ac circuits in coach with a plug in tester.