Generator Plugged Into 30amp Onboard System?

[JEdward]

We now have 2000 watt external/portable generator. When I plug in (3-prong 110v) to the generator, connected to 30amp shore power, the "reversed polarity" light comes on at master panel at nav station? Have used one 3-prong (110v) plug to 30amp shore power system with no problem at docks and boatyards when 30amp connection is not available, with no problem.
Is there a reason the 2000w generator would cause reversed polarity warning light to come on?
Does the low- (or no-) power production of the generator - when nothing is plugged in to draw power - cause this light to come on? As a test, turned on AC water heater to draw high power. Generator revs up, and "reversed polarity" warning light goes off, as if all is well?
Any help and suggestions will be much appreciated.
JEdward

[twistedtree]

The first thing I would check is the see if the neutral and ground are connected inside the generator. This bonding is supposed to happen at the "power source". In a house, that's at the main electric panel, btu on a boat it gets more complicated since there are several potential power sources. When you are connected to shore power, the neutral ground bond is made in the power panel that serves the dock, just like for a house. When you connect your boat to that shore power, you use the shore-side bonding.

In your case, the generator is the power source, so it should bond the neutral and ground. Some generators do that, and some don't. The alarm panel in your boat is likely looking for a voltage difference between neutral and ground, which it would find if the neutral and hot are mixed up. Without proper bonding, the neutral is floating (in the electrical sense) and there is likely to be a voltage between it and ground.

If you have a handheld electric meter, check for continuity between between neutral and ground at the generator plug. The generator should be off, of course, with nothing plugged into it. I'm guessing you will find there is no continuity. You can also check the generator's manual to see what it says.

If this isn't the problem, well, ignore everything I've said.

[The Garbone]

There may be nothing wrong with your generator at all. Most power heads are designed to run and self regulate under load. In general running a gen set with zero load is bad for the power head internals. I work with a lot of generators in my and when we run them up for maintenance we attach a heat sink dummy load if no live load is available. On out bigger gens if we hook them to smaller loads we will also add a dummy to in order to lower stress on the power head.

[JEdward]

I now understand it is the (a) no/low load and (b) the internal grounding of the genset (or lack thereof) causing the reverse polarity light on master panel at nav station to come on when genset is plugged into 30amp shore power system.
But, QUESTION: So what? Does it matter? Will any damage be done? Kinda' like using 2-prong 110v plugs, isn't it?
We use generator only for light loads at anchor: computer, phone charging and battery charger on the 30amp system.

[JEdward]

P.S. Also just now conducted new test with external ground line (into water) connected to genset external ground connection. No change. Reverse polarity light still on . . . EXCEPT when I put a heavier load on it?

[twistedtree]

The issue isn't whether the ground terminal on the generator is grounded or tied into the water, it's whether the ground and neutral are connected together in the generator. Have you been able to check that?

As for "is it OK to ignore", all I can say is that I wouldn't. All the safety measures built into proper electric wiring are there for a reason. When things work right, they are unneeded just like all safety measures. But when things go wrong, they save lives. You can decide what risk you want to take, and the extend to which you are happy putting other people around you at risk. Just let me know where you are so I can stay away.....

[JEdward]

I appreciate the sense of humor! We are trying to be careful. (But, FYI, Boot Key Harbor, Marathon, FL.)
Will go buy tester today. What if they are connected inside generator? What if not connected?
Thank you.

[irwin37]

What kind of gen do you have, if its an inverter/gen then you most likely do not have a problem. IE. Honda 2000i as the inverter does not have a true ground and the neutral is not physically connected to device ground by design but is connected through solid state devices internal to the gen, at low current draws there is most likely some leakage causing the light to come on. I would check with the manufacture before doing anything.



John

[donradcliffe]

This is an old topic which has been previously beaten to death several times. Use the custom search function for "honda polarity".

The short answer is that your generator does not have the ground bonded to the neutral, and if you want to make the light go out you can do by connecting the neutral and ground at the plug. Nothing will break if you don't bond, but you should be aware that your system is slightly less safe.

[twistedtree]

Originally Posted by donradcliffe

This is an old topic which has been previously beaten to death several times. Use the custom search function for "honda polarity".

The short answer is that your generator does not have the ground bonded to the neutral, and if you want to make the light go out you can do by connecting the neutral and ground at the plug. Nothing will break if you don't bond, but you should be aware that your system is slightly less safe.

Well, there you have it.

The only further suggestion I would have is to make the change at the wiring for the receptacle in the generator, not in your shore power cord. It's teh generator wiring that's wrong, and fixing it there will make it work with any power cord, not just your special modified one. Also, if you modify the cord instead then you have a cord which is wired improperly anytime you plug it into a proper outlet.

[AnchorageGuy]

Originally Posted by donradcliffe

This is an old topic which has been previously beaten to death several times. Use the custom search function for "honda polarity".

The short answer is that your generator does not have the ground bonded to the neutral, and if you want to make the light go out you can do by connecting the neutral and ground at the plug. Nothing will break if you don't bond, but you should be aware that your system is slightly less safe.

Don is absolutely correct. We ran our 2000 for years with no issues with either the light or with the jumper on the Neutral/ground. You can do it internally or cut off an extension cord, jump the wires, seal the bare ends really well and plug it into the genset. That's what we did. Chuck

[Maine Sail]

Originally Posted by twistedtree

Well, there you have it.

The only further suggestion I would have is to make the change at the wiring for the receptacle in the generator, not in your shore power cord. It's teh generator wiring that's wrong, and fixing it there will make it work with any power cord, not just your special modified one. Also, if you modify the cord instead then you have a cord which is wired improperly anytime you plug it into a proper outlet.

I was doing some research on an issue with Honda inverter generators and ELCI's not to long ago. I contacted Honda about the neutral/grounding bond at the gen set and asked a litany of questions. I was bounced from department to department.. I went as high as I could get with their engineering department, 45 minutes on the phone bouncing around, and the bottom line is Honda insists that you NOT bond neutral/ground at the generator for the EU/inverter series generators.

Honda will not give any specifics as to "why", probably lawyer driven, but say it will void the warranty. I then called back and went down the OSHA path. OSHA requires neutral/ground tie at the generator. Honda simply told me not to use an EU/inverter generator on a job site.

That said people on the net have done it. I tried it on my own Honda and it suffered no ill effects. Still Honda has a reason for not doing this and they'd surely sell more generators, to OSHA inspected jobs sites, if they did.. I am certain there is a good reason but Honda will not disclose any specifics..

Perhaps someone out there knows "why" Honda says not to bond neutral/ground???

[JEdward]

Thanks to all. Rewired plug per your suggestions. Generator running, no polarity light. Low load AC power working fine.
JEdward

[twistedtree]

Originally Posted by Maine Sail

I was doing some research on an issue with Honda inverter generators and ELCI's not to long ago. I contacted Honda about the neutral/grounding bond at the gen set and asked a litany of questions. I was bounced from department to department.. I went as high as I could get with their engineering department, 45 minutes on the phone bouncing around, and the bottom line is Honda insists that you NOT bond neutral/ground at the generator for the EU/inverter series generators.

Honda will not give any specifics as to "why", probably lawyer driven, but say it will void the warranty. I then called back and went down the OSHA path. OSHA requires neutral/ground tie at the generator. Honda simply told me not to use an EU/inverter generator on a job site.

That said people on the net have done it. I tried it on my own Honda and it suffered no ill effects. Still Honda has a reason for not doing this and they'd surely sell more generators, to OSHA inspected jobs sites, if they did.. I am certain there is a good reason but Honda will not disclose any specifics..

Perhaps someone out there knows "why" Honda says not to bond neutral/ground???

Maybe their inverter output isn't really floating relative to ground? It would be interesting to see what the ground to neutral voltage is with the two disconnected, and if there is any measurable current flow when they are connected. Except I don't have one to play with. Oh well.

[Maine Sail]

Originally Posted by twistedtree

Maybe their inverter output isn't really floating relative to ground? It would be interesting to see what the ground to neutral voltage is with the two disconnected, and if there is any measurable current flow when they are connected. Except I don't have one to play with. Oh well.

That is what I suspect but Honda will not leak any information about this other than to say it "voids warranty" and don't do it..... They must have a good reason.... I may test that when I get a chance...