Generator reverse polarity?

[TCW]

I have used my Yamaha 2400IS a number of times when dry camping and to charge the batteries. Today for the first time ever, I plugged the Surge Guard 34730 into the generator. It passed the power through, but the screen is reading reverse polarity and faulty ground. The faulty ground I can understand because the grounding system for the generator is not much. The reverse polarity has me stumped as I looked at the wiring diagram for the generator and the Red wire is connected to the vertical/horizontal blade side of the outlet and the Brown wire is connected to the vertical blade side as shown in the wiring diagram.

 

I tested the outlets inside the trailer with one of the small circuit testers and both yellow lights and the red light are on indicating reverse polarity and open ground. Same result plugging it directly into the generator outlet.

 

Has anyone else encountered this with their generator?

 

It would be fairly simple to switch the wires at outlet. It would be harder to get into the guts of the generator to see if the Red and Brown wires are reversed at that point. Any suggestions/recommendations would be greatly appreciated.

[Ed ke6bnl]

I have yammy 3000 and it will not work with my progressive dynamic surge protector. called them and they said to take an extra male plug and put a wire from the neutral to ground and plug it in the 110 v outlet when running with the PG surge protector. when I did all worked fine. might want to check with surge guard maybe the same answer not sure. Not sure but I think mine went off on no ground

[MNRon]

Search for threads on 'ground bonding' on this and other rv forums. Most likely your problem is as Ed G stated, that the generator does not 'bond' the ground (round bottom plug) and neutral (left wider plug). Therefore your surgeguard is complaining because it expects these two are tied together somewhere (at, and only at, source panel in your s&b home). Making a dummy plug as Ed suggests creates this 'bond' between gnd and neutral as the surgeguard expects. Very easy to do, but don't attempt unless your comfortable with wiring; if not I'm sure you can find someone handy that can help. Be safe.

[TCW]

Thanks for the responses! I did search as suggested and it seems that the surge protector manufactureres recommend against bonding the ground and the neutral on the generator. So I will either just use the genny as I have in the past or ignor the surge guard warning since it does pass the current. Thanks again for the quick responses!

[Ed ke6bnl]

My progressive surge did not let electricity go to the trailer without the mod.

[oldjohnt]

Seems like we discussed this in detail somewhere some time back, and there was a link describing which makes and models of portable gensets had FLOATING NEUTRALS and which had BONDED TO GROUND NEUTRALS.

 

If your Genset has its Neutral FLOATED detection and surge devices don't know which end is up lol

 

Its easy to jump wire the Neutral and Ground together by using a male plug or other simple methods, I prefer a Bonded to Ground Neutral configuration myself. If its NOT bonded a ground fault to the Safety Equipment Grounding Conductor (which is bonded to outer metal cases of some tools and appliances) does NOT pass fault current and will NOT trip the breaker. Its (safety equipment ground) like a bridge (wire) to nowhere. There's more to this story but nuff said for now.

 

NOTE inside the RV panel, unlike a homes panel, the Ground Buss and Neutral Buss are NOT bonded but separate and electrically isolated and insulated, which is why I prefer the energy source, be it the parks utility power pedestal or normal utility (which have Neutral to Ground Bond at transformer and main panel) or genset have a bonded to ground Neutral. If the genset powers a homes panel that's a different situation, because it gets a Neutral to ground bond there. Maybe that's why the genset manufacturer isn't concerned the genset itself has a floating Neutral, because at the homes panel Neutral is bonded to ground there.

 

A bit more technical, a genset which has a Neutral to Ground bond (often the gennys metal frame) is considered as a "Separately Derived Source" which is wired different then if not (floated) in which case its NOT a separate derived source. This has to do with Transfer Switch wiring.

 

If the genny fed my RV I would want a Bonded Neutral, but you do as you please. If it fed my home and I used a 2 pole transfer switch (2 hots if a 120/240, unswitched Neutral) I would use a Floating Neutral (NOT bonded to frame) and carry the equipment ground out to the gennys frame.

 

NOTE Im longgggggggg retired as an electrical power distribution engineer and rusty on this and the latest codes so NO WARRANTY do as the manufacturer or NEC says if different them me. Still above is how I would do it, do as you like

 

John T

[TCW]

...If the genny fed my RV I would want a Bonded Neutral...

I appreciate you comments and explanation. I don't know if it makes any difference in your discussion/recommendation, but the Yamaha EF2400IS has a ground terminal on the front panel which I always connect to a steel rod driven into the ground at least a foot.

[TCW]

I am continuing to research this and it seems that at least some Honda EU2000s have a similar configuration to the Yamaha. I know there are a lot of folks using Honda EU2000s, are you all using a bonding plug?

 

I also found a link to the Progressive Dynamics website that discusses their EMS. It states: "RV wiring is different than the wiring found in homes; the neutral and ground conductors are isolated in the RV, unlike in a home where they are tied together at the service panel. The reason is; homes have a bonded ground system, where as RV’s do not. Therefore never bond the neutral and ground together for any reason. This will create a ground fault condition, and may result in electric shock and or fire hazard."

 

So, is it different bonding at the generator? I really like to use both plugs on the generator, one for the RV the other for the charger for my trolling motor battery. Would it accomplish the same thing as the bonding plug to connect a wire from the second terminal of the neutral on the back of the outlet to the ground terminal of the outlet? If I do choose to do this, should I still use the grounding rod?

 

Thanks again to all who responded!

[oldjohnt]

TCW, when the manufacturer stated "Therefore never bond the neutral and ground together for any reason"

 

I don't know if they mean do NOT do that in the RV AC distribution panel OR do NOT do that at the genset????????????????

 

1) I agree NEVER do that in the RV AC Distribution Panel. You only want ONE Neutral Bond, so you would NOT do it at BOTH the genset (or utility) and panel. The RV panel is different in that its considered as a SUB PANEL since the RV park already has a Neutral to Ground bond and you don't want to do that twice therefore the Neutral and Ground are separate and isolated and insulated in the RV sub panel. THAT PART IM DEFINITELY SURE OF

 

2) In the event the genset were a conventional device with a stator and rotor etc., non inverter, I would DEFINITELY Bond its Neutral to its case/frame. IM SURE OF THAT PART, IF ITS A NON INVERTER GENSET I WOULD BOND NEUTRAL TO CASE/FRAME INSTEAD OF FLOAT THE NEUTRAL. That way its the same as a utility transformer and is considered by the NEC as a Separately Derived Source. The utility transformer has Neutral bonded to the steel case and a No 4 copper wire from there down to earth ground. Then at the homes panel Neutral is bonded to mother earth and the Ground Buss is bonded to the Neutral Buss.

 

HOWEVER THE UNKNOWN TO ME IS IF ITS AN INVERTER GENERATOR (unlike a conventional wound unit) it may NOT have a true Neutral but an isolation transformer output with 120 VAC line to line. NO TRUE NEUTRAL

 

THATS WHY I HESITATE TO DO OFFER ANY ADVICE DIFFERENT FROM WHAT THE VENDOR SAYS (if its an Inverter instead of a conventional genset) because I don't know how its wired and configured and if its output is essentially an isolation transformer 120 VAC line to line with NO TRUE NEUTRAL

 

 

You mentioned "has a ground terminal on the front panel which I always connect to a steel rod driven into the ground at least a foot."

 

That doesn't help much !!!!!!!! As I best recall from the NEC (no warranty been too long), In the event a genset is used to power plug and cord connected equipment from onboard receptacles, NO CONNECTION TO A GROUNDING ELECTRODE IS REQUIRED. However, if its used to feed a panelboard or non onboard receptacles A GROUNDING ELECTRODE IS REQUIRED. Then a Grounding electrode can be several different things, but a one foot rod does not suffice BUT IT WONT HURT ANYTHING

 

However, that ground connection you're talking about may be intended as a RV case frame 12 VDC Negative ground and has nothing to do with an NEC earth grounding electrode, so I don't think any earth ground is what its intended for, ESPECIALLY if its an Inverter

 

SUMMARY I know for sure how to deal with a wound genset, but if its an Inverter (makes its own 120 VAC from a DC generator electronically) I dont know if it has essentially an isolation transformer output 120 VAC line to line with no true Neutral SO IM NOT SAYING BOND NEUTRAL TO GROUND AS I WOULD ON A WOUND GENSET,,,,,,,,,,,, BUT DO AS MANUFACTURER SAYS.

 

Sorry, I cant answer your question other then in a conventional non inverter genset I would definitely bond Neutral and Ground (at the Genset) and NOT float the Neutral. If your genset has a true Neutral and were 240 line to line but 120 line to a center tapped Neutral I WOULD BOND NEUTRAL TO CASE FRAME AND your surge and detectors would all work correct

 

Anybody have the same Genset and can tell us if it has a true Neutral and/or if they used a bonding device and all worked fine????????????????????

 

John T

[TCW]

...HOWEVER THE UNKNOWN TO ME IS IF ITS AN INVERTER GENERATOR (unlike a conventional wound unit) it may NOT have a true Neutral but an isolation transformer output with 120 VAC line to line. NO TRUE NEUTRAL...However, that ground connection you're talking about may be intended as a RV case frame 12 VDC Negative ground and has nothing to do with an NEC earth grounding electrode, so I don't think any earth ground is what its intended for, ESPECIALLY if its an Inverter...

The Yamaha EF2400IS is an inverter generator. The instruction manual very clearly shows connecting the ground terminal on the front of the generator to a rod driven into the ground.

[Randyretired]

This gets into area that has killed a number of people swimming around boats. Without the ground bonded to the neutral there could be a shock hazard in the RV. However, with the ground bonded without an earth ground the entire RV is now energized and potentially a shock hazard from the earth to the RV. Some advocate GFI is the only safe way to power without an earth ground.

[TCW]

This gets into area that has killed a number of people swimming around boats. Without the ground bonded to the neutral there could be a shock hazard in the RV. However, with the ground bonded without an earth ground the entire RV is now energized and potentially a shock hazard from the earth to the RV. Some advocate GFI is the only safe way to power without an earth ground.

I understand the shock hazard in a boat if the ground bond causes the boat hull to be energized. So what is the shock hazard in the RV without the ground bonded? The GFCI not working?

 

Having the RV energized does not sound like a very good idea. How does one add GFI to the connection circuit to the generator?

 

There have got to be thousands of RVers using Honda and Yamaha generators. If they are that unsafe to use as originally designed, I would think there would be warnings not to use them to power an RV, lots of recalls, law suits, etc.

 

This brings up another question. How is powering from the inverter of the generator any different than powering from an inverter connected to a battery bank?

[Randyretired]

TCW, You bring up some very good points. I will try to expand on some of these. First GFCI's work with or without earth grounds. No worries there. When the ground and neutral are not bonded you are surrounded by a conductor that isn't tied to ground. As long as everything is working properly this is not a problem. However, a malfunction could easily energize this. This means anything you touch could be a shock hazard. This is why everything in a house is grounded even the water pipes. Think for just a minute about all of the malfunctions that can cause this. A wire in an appliance or the hotwater heater element failing to name a few. In reality most things function just fine and the ground is just an insurance policy that may never be used.

GFI's work and can easily be added to virtually any power source by running the lines through a GFCI before anything else. In our houseboat we ran everything through either a GFCI plug or breaker. This included the inverter and the generator. In an RV things are generally dry so the potential dangers are not as bad. I think that that leaving the nuetral open from the ground in a application that doesn't have an earth ground might be the best of the alternatives without GFI.

[TCW]

...GFI's work and can easily be added to virtually any power source by running the lines through a GFCI before anything else. In our houseboat we ran everything through either a GFCI plug or breaker. This included the inverter and the generator...

Thank you for your most helpful response. A couple last questions. If I wire up an outlet like this and then plug it into the generator and then plug the RV into that outlet, the shock hazards in the RV would be reduced? Does the GFCI outlet just get wired in the standard three wire configuration? I seem to remember when GFCIs were first required near water sources, some folks with old two wire receptacles and only two wire wiring would make the GFCI work by bonding the neutral and ground of the GFCI outlet.

[TCW]

Still researching solutions. Would replacing the male end on a dogbone like this with a GFCI plug like this solve the problem?

[oldjohnt]

TCW

 

1. YOU STATE:

The Yamaha EF2400IS is an inverter generator. The instruction manual very clearly shows connecting the ground terminal on the front of the generator to a rod driven into the ground.

 

Sounds fine to me. With portable gensets the NEC does NOT require a Grounding Electrode if plug and cord connected tools are fed via onboard receptacles, otherwise one is required. Since they have no idea what you’re using the genset for, connecting to a Grounding Electrode would be my same advise. NOTE an NEC Grounding Electrode may be several different items, but its MORE then a short rod in the ground HOWEVER a genset is not same as the utility either, it takes a lot to explain all that and Im not doing it here

 

1. YOU STATE

I understand the shock hazard in a boat if the ground bond causes the boat hull to be energized. So what is the shock hazard in the RV without the ground bonded? The GFCI not working?

If a live hot wire became shorted to the RV skin/frame, you first want it bonded to the RV panels Equipment Ground Buss, and that must be bonded somewhere (usually at parks main dist panel) to the Neutral Buss. That way the Grounding conductor (Bare/Green) can conduct fault current so the breaker trips and de energizes the skin/frame so you don’t die. THAT’S THE SHOCK HAZARD IF THERES NO BONDED GROUND TO NEUTRAL PLUS THE SKIN FRAME BONDED TO GROUND BUSS

1. Having the RV energized does not sound like a very good idea. How does one add GFI to the connection circuit to the generator?

You prevent the RV from being energized by bonding it to the Equipment Grounding Conductor which is bonded to the Neutral (just not in the RV panel). There are GFCI devices or there can be GFCI circuit breakers in the panelboard.

NOTE if the RV skin/frame is NOT bonded to the Ground Buss and a hot wire shorts to it, it remains hot and energized and can kill you if touched especially if barefoot on wet ground. ALSO as described above, if theres no Neutral to Equipment Ground Buss, theres no path for return fault current to trip the breaker so the skin/frame remains hot and energized

 

1. There have got to be thousands of RVers using Honda and Yamaha generators. If they are that unsafe to use as originally designed, I would think there would be warnings not to use them to power an RV, lots of recalls, law suits, etc.

That’s why they have instructions (besides an electrical engineer, Im also an attorney and know whay they post those lol) If used correct theres no more, actually less with respect to mother earth shock hazards, then if connected to the grounded utility.

 

1. This brings up another question. How is powering from the inverter of the generator any different than powering from an inverter connected to a battery bank?

Actually depending on Inverter or inverter generator design, theres littlde difference. ITS JUST THAT I DON’T KNOW IF THE OUTPUT IS AN ISOLATION TRANSFORMER 120 VAC LINE TO LINE WITH NO TRUE NEUTRAL OR NOT. If it’s a 120/240 genset with a center tapped output transformer that functions more like a wound generator and likely does have a true Neutral and I know how to deal with that.

 

1. No that dog bone does NOTHING about Neutral Ground bonding. There are many many non inverter wound gensets and on those if the Neutral was floated I WOULD BOND IT TO CASE FRAME. Again Im not going to explain why, takes too long. Again an Inverter may or may not have a true Neutral anyway, an isolation transformer output 120 line to line

 

SWIMMING POOLS AND RV’S

 

At the pool you want all the pumps and filters and ladders down into the water and all electrical devices well bonded to the equipment ground buss and it well bonded to the Neutral WELL DUH Same as in the RV, you want its skin frame bonded to the ground buss and back at the main panel it bonded to Neutral

 

 

1. Will a GFCI help YES iffffffffffffffff it first recognizes the input circuit and its correct??? But it looks for an imbalance (5 milliamps) in Hot versus Neutral and if all flowing out is returned by the Neutral and NOT elsewhere, so if theres no Neutral Id have to see the schematic to answer the question IN GENERAL THOSE ARE FOR GROUNDED INSTEAD OF FLOATING SYSTEMS, I WOULDN’T BET DIME IT WILL WORK FOR AN ISOLATED INVERTER SYSTEM, BUT I CANT SAY ABSENT THE DIAGRAM???????????????

 

DISCLAIMER

 

Its impossible to fully answer and explain what I learned over 40 years about Neutral and Ground bonding into a few paragraphs here a laymen can understand, so these answers are not complete or exactly perfect, there are a ton more explanations in order but I only have so much time and probably lost lay people anyway. Again an isolation transformer output with no true neutral drives GFCI or testers crazy but that don’t necessarily mean it cant be safe. I understand the differences in bonded or floating systems but cant begin to explain it all here so will not even try.

 

If in doubt, do what the manufacturer suggests NOT what I say. Still, if I had a wound 120/240 volt genset with a true center tapped neutral and sure It can work either way I WOULD BOND THE NEUTRAL INSTEAD OF FLOAT IT so it acts like the utility and protectors work just fine. However if its 120 only line to line with no true neutral, that’s a different story which Im not going to cover here.

 

Way too much said, sorry, engineers and attorneys cant help themselves lol

 

John T

[TCW]

Well, time to bring this topiv to a close. I greatly appreciate the time and effort taken by all those who responded. I finally got through to Yamaha technical support and they recommend using the generator as is from the factory. They recommend against bonding the ground and neutral and recommended not to use a GFCI between the Generator and RV. Thanks again to all who responded!!!

[oldjohnt]

To bed is fine by me lol AFTER one more remark to your statement " They recommend against bonding the ground and neutral and recommended not to use a GFCI between the Generator and RV."

 

That dont surprise me:

 

a) If its an inverter with an isolation transformer output and no true Neutral (like a center tapped 120/240 output) a GFCI may not work properly anyway

 

If the output has no true Neutral but still wired to the "Neutral" terminal on a regular outlet, I can see why they would NOT want that bonded to the case/frame.

 

But its still not dangerous as manufactured and will work fine to power appliances, it just works different then a utility transformer or a normal wound non inverter genset.

 

When you see talk of creating your own Neutral to ground Bond if a genset is currently floating the Neutral (AND WHAT I RECOMMEND PROVIDED PROPER TRANSFER METHOD IS USED) , that's talking about a non inverter 120/240 center tapped wound generator NOT an Inverter using an isolation transformer 120 line to line no true neutral generator AT LEAST THATS WHAT IM THINKING

 

Best wishes yall, hope I didn't confuse everyone

 

John T