Reverse Polarity with Generator

[Vincentc]

I ran the generator today for the first time with the inverter switched on. With the generator running, the reverse polarity lights on the breaker to the inverter and ones on the sub panel came on. There are no polarity issues when the shore power feeds the inverter.

Until I wired the inverter, there was no polarity indicator other than the polarity light for the shore power. This generator was installed 6 years ago by the PO.

Other than an improper generator connection, is there an explanation for the polarity lights to come on?

Thanks,

[gbharrington]

Is it an inverter/charger?

[SKYCHENEY]

Get out your multimeter. It should be pretty easy to check it.

[MikeP]

Since it seems to have started with the installation/use of the inverter, the inverter-related connections are the ones I'd check first. I assume that the inverter is "sharing" the circuits with the genney/shore power circuits, right? That is, when the shore/genny is running, circuit X receives power from either of those and when the genny is not running/shore is disconnected, the inverter runs circuit X.

If so, does the inverter take up the load automatically (pass-through) or do you turn it on when you want it to operate the appropriate circuits?

[Vincentc]

I wonder if the inverter install is a cause or a coincidence since until the install, I do not think there was anything to indicate reversed polarity for the generator.

It is an inverter / charger.
The AC feed for the inverter comes after the selector switch for shore power or generator and leads to a 30 amp breaker which allows me to shut off the AC to the inverter. The inverter passes power thru to a sub panel for the port, stbd, and refrigerator outlets. That same AC line also feeds a rotary switch allowing me to take power directly from the selector without passing thru the inverter.

There are no polarity issues indicated when running off shore power or passing shore power through the inverter, and no issues when running off the inverter.

With the generator running, there are polarity warnings both on pass thru and direct with the inverter turned off.

Thanks

[Vincentc]

The Mystery Expands,

I used a digital multimeter to check voltage at the main ac switch.

I removed the inverter from the circuit:

off shore power

Hot to Neutral = 123 volts
Neutral to Ground = 0.4 volts
Hot to Ground = 123 volts


off Generator

Hot to Neutral = 118 volts
Neutral to Ground = 49 volts
Hot to Ground = 69 volts

Makes no sense to me

[Pete]

Sounds like the generator ground is not connected. When the generator was wired one wire off the generator AC output should be grounded to polarize the output. I suggest you get the generator manual out, look up the electric hookup instructions, focus on the grounding required, and modify your setup as needed. If it is the original Hatteras installation, something is loose or corroded in the grounding at the generator.

Pete

[MikeP]

Agree with Pete - Your measurements indicate, contrary to what I thought earlier, that there's a genny connection problem. Sort out the genny connections and then re check polarity.

I've have a fairly long suggestion partially written re the inverter setup but if the above solves the problem then no need to go further.

[Pete]

Just one additional item, the polarity light. These indicators are just a light bulb with one lead on the green wire ground and one on the white wire neutral. Since your white wire and ground (bonding system) are not properly connected the 49 volts you are reading cause the light to be on. Bottom line, the polarity light problem will also be fixed when the grounding is corrected.

Pete

[Vincentc]

I've looked at the generator ground and the green wire is attached to a connection next to the 12v starter connections and leads under the generator rather than with the black and white wires leading aft to the ac panel.

I will try to check and see to what and how well the ground wire is attached under the generator.

Without opening things up I cannot see how the wiring to the AC panel is connected.

The rating plate for the generator states 120/240 volt and 75/37.5 amps.
As best I can tell, there are no 240v circuits on the boat.

The generator is a 2008 9kw Cummins/Onan purchased by the previous owner and installed by a dealer in Orlando, FL

thanks

[Pete]

Vincent,

Since you know the company that installed the generator, I would suggest contacting them and telling them you have a "floating neutral" problem with the generator and inquire if they can tell you where the neutral should be tied to ground. A lot easier than tearing things apart, and hopefully they have a consistent way they wire replacement units they can explain.

Pete

[Vincentc]

Pete,

Good suggestion.

I will try that.

thanks

[Vincentc]

I spoke to the selling/installing dealer, who is in Bradenton, FL not Orlando, but in any case a long way from Pascagoula, Mississippi. I was told that it is wired according to the diagram posted inside the generator cover.
Yesterday I pulled the cover and looked at the diagram.

http://i1123.photobucket.com/albums/l554/vjcast/Lilly%20Marie%20Generator/PA300257GeneratorDiagram.jpg (http://s1123.photobucket.com/user/vjcast/media/Lilly%20Marie%20Generator/PA300257GeneratorDiagram.jpg.html)

The label on the front of the generator indicates that it is set up as 120/240v

http://i1123.photobucket.com/albums/l554/vjcast/Lilly%20Marie%20Generator/PA270254genlabel2R.jpg (http://s1123.photobucket.com/user/vjcast/media/Lilly%20Marie%20Generator/PA270254genlabel2R.jpg.html)

The Generator is wired as shown:

http://i1123.photobucket.com/albums/l554/vjcast/Lilly%20Marie%20Generator/PA270243GenwireconnectionsfromtopR.jpg (http://s1123.photobucket.com/user/vjcast/media/Lilly%20Marie%20Generator/PA270243GenwireconnectionsfromtopR.jpg.html)

The wires going to the breaker and hot wire are labeled "T-1" and T-3" and the "T-2" and "T-4" going to the neutral wire appears consistent with the diagram IF the generator set up as 120v. On the other hand the generator label indicates it is 120/240.

My confidence level in the installation is reduced by the fact that 9kw (75 amps) appears to be run through one half of a double 40 amp breaker. There is no connection to the second 40 amp breaker. As long as we have had the boat, the breaker has tripped whenever we ran both air conditioners at the same time as the stove.

I am going to get back in touch with the dealer who installed it, but would appreciate any insight you may have on this. I plan on having a closer Onan dealer come out and take a look, but I would like to know more about this to better understand what I might be told.

Thanks for your advice.

[Vincentc]

A few more facts.

The generator is wired from its double pole 40 amp breaker, shown in the upper right

front:
http://i1123.photobucket.com/albums/l554/vjcast/Lilly%20Marie%20Generator/PA270236BattandGndconnectionsr.jpg (http://s1123.photobucket.com/user/vjcast/media/Lilly%20Marie%20Generator/PA270236BattandGndconnectionsr.jpg.html)

Back:
http://i1123.photobucket.com/albums/l554/vjcast/Lilly%20Marie%20Generator/PA270246breajerbackR.jpg (http://s1123.photobucket.com/user/vjcast/media/Lilly%20Marie%20Generator/PA270246breajerbackR.jpg.html)


to a single breaker which in turn is connected to wiring for both the 30 amp air conditioner panel and the 30 amp ship service panel.

http://i1123.photobucket.com/albums/l554/vjcast/Lilly%20Marie%20Generator/PA270244BoatBreakerr.jpg (http://s1123.photobucket.com/user/vjcast/media/Lilly%20Marie%20Generator/PA270244BoatBreakerr.jpg.html)

The grounding wire from the exterior of the generator leads to the boat's grounding/bonding strip which runs alongside the port engine stringer. The grounding wires for the two 30 amp circuits are connected inside the generator as shown in the previous post.

The labeling is my addition due to the repeated need to go down and reset the breaker.

Thanks

[bostonhatteras]

The single 40 amp breaker serving the entire boat when run on the generator doesn't surprise me. My boat had the air conditioning panel wired through the main A.C. selector switch for running on the generator. I still had to switch both selectors to gen but the feed came off the main A.C. Switch, not a separate feed. Their was no separate and distinct wire run from the generator output to the air conditioning panel selector switch. The set up ran things just fine for me but I wanted it separate so I changed it with two 30 amp breakers off the generator. I assumed hatteras figured you would be using that much less electricity away from the dock. I did think it was a sort of cheap way of hatt to do it. Would another wire run to the panels been that expensive for them? I have a 8kw by the way.

[Vincentc]

Boston,

I don't have a problem with the Hatteras wiring. Their breaker has never tripped, it is the 40 amp breaker on the 75 amp generator that sends me down into the ER.

There are two sets of very large wires going from the Hatteras breaker to the two 30 amp panels, each with its own rotary switch on our boat.

Regards

[gbharrington]

I have been waiting for the more knowledgeable "sparky" types to weigh in on this, but I do have a couple of thoughts. As far as the labeling goes, I believe it just means that your generator is capable of producing either voltage, depending on your needs.

As far as only one side the double 40A breaker being used, it doesn't make much sense. The wiring diagram for my boat shows a 2 pole 65A breaker (7.5kw gen) splitting into 2 lines, 1 for the main service panel and 1 for the AC panel. Have you considered upgrading to a 80A breaker?

[gbharrington]

As I re-read this for the 5th or 6th time, I'm now confused as to which breaker is tripping. The one labeled "Generator No. 1" or the Onan breaker on the gen?

[Andy B]

If it's the onan brk tripping what you need to do is run two properly sized jumper wires on the 40 amp brkr across the terminals load side to load , and line to line, if you don't you will never get rated power from the gen.

[Vincentc]

Greg,
The breaker on the Onan is that one that is tripping. The breaker labeled Generator 1 has never tripped.

Regarding upgrading the generator breaker. Until I opened things up, I assumed both poles of the double breaker on the generator were being used. I agree with your suggestion regarding using both sides of the double breaker and replacing the single hot wire between the breaker on the generator and the breaker on the bulkhead labeled "generator 1. I do not want to change anything until I find out what I am dealing with, and be sure it is done correctly.

Regarding 120 vs 120/240. I believe there is a difference. As shown in the wiring diagram which I photographed, in a 120/240 setup, two of the 4 wires coming out of the generator are hot, each carrying 120v. As I understand it, but do not claim to know, If they are combined, you get 240 volt, if they are connected separately, one to each pole of the double pole breaker you get 120v on each leg.

I have spoken to the service rep a Dog River Marina who said he could probably send a technician over next week to sort this out for me.

Regards

[Andy B]

Onan uses a 40 amp brk so it work wired 240 and 120 .when the gen is wired 120v. the brk needs jumped,it was installed incorrectly a good tech will be able to sort it out.

[Vincentc]

I contacted Magnum regarding the question of whether the Inverter install could be causing the polarity issue and Darren at their tech support replied (confirming what Pete said):

The issue you are describing is usually caused by a loss of the ground connection. I would check back at the generator and make sure you have a good ground and that the neutral and ground are bonded at the generator.

I checked the ground connection between the generator case and the bonding strip running alongside the port engine stringer. That connection is good; however, nearby connections between the bonding/grounding strip and thru hulls and the engine support were broken at the terminals. I guess that is to be expected in a 30 year old boat. Not sure if those bad connections would affect the generator ground. I assume that more important are the grounding wires connected to strap inside the generator, and whether they are properly connected to the grounding buss at the main panel.

I am going to have on a qualified technician check and correct the installation, but would like to understand the problem.

Thanks

[MikeP]

A few thoughts...

The wording is a little confusing to me:

". I would check back at the generator and make sure you have a good ground and that the neutral and ground are bonded at the generator."

I frankly can't tell if the tech is saying that:

the generator's ground (green) wire and the generator's neutral (white) wire are to be connected together ("bonded") at the genny and then there is a wire from that connecting point to the ground buss.

OR

If he means the ground/neutral are connected at the genny and then a wire is run from that connection to the neutral buss

OR

If he means the genny's neutral and ground are connected at the genny and then connected with a wire to the bonding system.

Frankly, none of the above seem correct..but, as I said, I may totally misunderstand what he is saying and he didn't mean any of the above.

FWIW, on our NL genny, the neutral wire goes to the neutral buss, the ground wire goes to the ground buss and the genny chassis is connected to the boat's bonding system. This, to me, is "normal" wiring. If the genny ground/neutral is connected directly to the bonding circuit, there are a lot of connections/additional wiring between that connection and the actual ground or neutral buss, all subject to corrosion/failure.

[Pete]

Vincent, it appears that you have two problems, a floating ground at the generator and a wiring/breaker problem. As for the folks that did the installation, I would not invite them back. So lets deal with the grounding first.

If you look at the diagrams you provided with the wiring alternatives, you are wired for 120 volts. So your setup is the left hand column of the three on the wiring diagram. Drop down to the left hand box labelled "schematic". Here you see T1 and T3 tied together going to a breaker and serving as the L1 or hot connector. Next you see T2 and T4 tied together and providing the L0 or neutral wire. As I read your description of the wiring and look at the pictures all of this is correctly done. Now drop down to the next left box labelled "Diagram Grounded Neutral". The next box down is labelled "Diagram Isolated Neutral". The difference between the two is a jumper from the L0 standoff to ground or not. From your picture there is no jumper thus you are wired for a floating neutral. This fix may be as simple as installing that jumper, but someone with electrical skills should definitely double check my conclusions and do any electrical modifications.

The second problem is the 40 amp breaker is definitely too low a rating. Again a person with electrical skills should check the wire size between the generator and the panels in the boat and replace the breaker with one that supports the capability of the wire. It looks like at least #6, perhaps #4 wire so you can at least go to a 50 breaker and perhaps to 70 amps

These two items should get you to a base that will support the installation of your inverter, fix the polarity light, and give you increased electrical capacity when running on the generator.

That is my take of your situation, which is two rather simple fixes.

Pete

[Boatnut]

I also find this thread a bit confusing, but I confuse easily.

A couple of things for what they may be worth.

The 120/240 labeling simply means the generator is capable of producing 120 volts or 240 volts, depending on how it is set up.

When it is set up to produce 120 volts, then the load current is double what is needed on 230 volts. If it is producing 120 volts and you have a 40 amp breaker it is going to trip. I would not suggest jumping the breaker, that would eliminate current protection for the generator, the breaker should be replaced with a breaker with the proper rating. It is possible the generator is set up for 230 volts, and whoever installed it split the load from the generator into 2, 120 volt circuits, the would avoid the need to replace the lower rated breakers.

The reading of neutral to ground of 49 volts and hot to ground of 69 volts is defineately incorrect, indicating a problem with the generator wiring. Note 49 plus 69 equals 118 volts. As you stated this problem started with the installation of a charger inverter, it sounds like somehow the ground and neutral wire were messed with. Perhaps the installer reveresd hot and neutral at the inverter. What is sometimes quite confusing is that mechanical connections and electrical connections are not always physically located in the same place.

In any event, until this problem is resloved you have a dangerous situation being that there is a voltage difference between neutral and the safety ground. Please be careful.

One of my major agrevations with electrical work being done by contractors, is many do not seem to have any respect for standards and codes. They also do not seen to deem it necessary to leave a drawing indicating what they did, so someone else can understand it, when they work on it. Some consider this job security, thinking they will be the only ones who can fix it again. When they do this the next guy has to charge the customer additional time to figure out what the idiot before him did, this can sometimes lead to higher cost for repairs.

Hope this helps, if you have any questions shout out, If I don't the answer I'll tell you so. and will usually find someone who does know. Sometimes the best service guy is the one who knows when he doesn't know. Electricity is a pain in the butt to those who do not work with it, it's even a pain in the butt sometimes when those of us who are supposed to know work on it. LOL

Good luck lets us know what you find, so we all learn.

[Vincentc]

I apologized for any confusion I created.

As shown in post 13, the generator label indicates "as manufactured - 120/240". When you refer to how it is "set up" does that mean how the 4 wires are connected, or is there some internal change made to the generator?

If I read the wiring diagram, the logical way to connect the generator would be to connect the two 120 hot leads, one to each pole of the double pole 40 amp breaker, and then connect one pole to the air conditioner circuit and the other pole to the ship service circuit. Since the breaker on the generator is a double pole 40, that seems to go along with a 120/240 set up.

Regarding the question of whether the inverter install is related to the polarity issue, I do not think it is.

The polarity problem was discovered after the inverter install, but until the install there were no indicators on the boat to reveal the problem. As part of the install, polarity indicator lights were added which indicated the problem which I confirmed with a volt meter.

Polarity is correct when operating on shore power with or without the inverter connected. Polarity is incorrect when taking power from the generator, with the inverter disconnected from all circuits.

Thanks

[SKYCHENEY]

Pete has this correct. It is configured for one 120v service or output right now. If you want to split to two 120v outputs, then you would need to configure it for the 240v setting and run one hot to the A/C panel and the other to the Ships service panel. I don't think that is necessary as you will need to have two selector switches, one for each panel. Leave it as it is with the 120v configuration and just make the two changes that Pete has suggested. That is the easiest and cheapest way to solve the problem.

[Boatnut]

To answer you question about connections, the connections are made at a specified location in the generator, typically a phenalyc boart with terminals, or by tying the wires from the generator together. This is where an owners maunual is invaluable.





I agree that Pete is onto the problem. I do find it interesting that the generator is so large, did Hatteras put 9KW generators on 43's. It sounds like the previous owner may have upsized things a bit. The fact that you have 40 amp breakers suggests either a smaller generator was originally installed, or the boat was wired for 230 somewhere along in it's life. To be properly protected not only does the breaker need to be the correct size, the wire also needs to be the correct size.

You mentioned you have to go to the Genny room to reset the breaker. With one what you have available, you might consider restrapping the generator to 230, and using one 120 leg for ac, and the other 120 leg for the house. This arrangement splits the load, and breaker replacement may not be needed. This is as Sky mentioned not the cheapest way, but it may be the more advantageous way.

The generator wire connected to the 12 volt starter, gets me thinking. Not the way I would think a good electrician would do it.. There should be a ground buss and a neutral buss on board, the generator should be connected at those points. the neutral and ground would be connected together at the generator, but not between the busses. Do not connect the neutral and ground together anywhere on the boat except at the generator, on shore power neutral and ground are connected atthe marina power source.


Electricity will always seek a path to ground, it doesn't care very much which way it goes, it just follows the path of least resistance.

[SKYCHENEY]

Our 1975 43DC came with a 7.5KW Onan.

[Vincentc]

The PO purchased a new generator in 2008, a 9 kW cummins Onan which was installed by the dealer in Bradenton, FL. I bought the boat a few months later and brought it to Mississippi. During the trip home the generator stopped working. I telephoned the dealer, he suggested I contact a dealer in my area. That dealer replaced a controller computer board under warranty, and the generator performed fine since. I do not recall that tech doing anything to check the polarity of the generator output.

In my conversation in 2008 with the FL dealer, he mentioned there was an earlier service call which noted that the generator would not work due to a bad ground.

Yesterday, I checked for continuity between various grounding points on the generator and the grounding buss (green wire) at the main electric panel.

There is continuity between the green buss and the grounding wire on the outside of the generator and between the grounding wires connected inside the generator. There is no continuity with the generator neutral connection.

I am suspicious of the fact that the generator is wired as if it were 120v when the generator is labeled 120/240 75/37.5 amps, and it has a double pole 40 amp breaker to protect it. As shown in post 13, the wiring diagram for the generator shows two output wires attached separately, one to L1 and the other to L2.

I emailed the selling dealer Wednesday and specifically asked if they had reconfigured the generator from 120/240 to 120. No response yet. I also asked about a floating neutral.

There are already two separate 30 amp panels, rotary switches, and wiring back to the generator. The separate wires are combined into one circuit at the boats generator circuit breaker. That combination makes sense for a 120v output generator. Seems like for a 120/240, a second boat breaker should have been added to allow separate 120v circuits from the generator to ship service and air conditioner panels.

I hope To have a capable boat electrician out to the boat soon.

Thanks for the comments

[SKYCHENEY]

Its obvious that the generator is currently wired for 120v only.

[Boatnut]

Good idea to have a qualified electrician take a look. You mentioned there is not continuity between neutral and ground. Things a starting to make more sense to me now (I think). If you look at the reconnection drawings you will see a set up for an isolated neutral. My next check would be to check for continuity between neutral and ground for the ships shore service. It might be possible the ships service has ground and neutral tied together, (they are most certainly tied together at the soure and/or pedistal) If the generator is wired with a isolated neutral and ground and neutral are tied together at ships service, it's my guess just about anything could result, becuase you have now tied neutral and ground together on an isolated neutral source.

It would ne great to be close enough to come over and give you a hand. Unfortuneatly, all we can do is theorize and give places to check. Some pretty shrp guys on here, and you have been given some good advice.

BTW, if L1 and L2 have wires going to breakers, take a voltage reading between L1 and L2 that reading will tell what voltage the genny is set up for.

[Vincentc]

Thanks

T1 and 3 are tied together. And T2 and 4 are combined, consistent with the 120v diagram.

Hope to have a capable tech out soon. I am not going to change anything before then. I will report the results.

Regards

[Vincentc]

I still plan on letting you all know the results of the inspection by a qualified technician, but I am still waiting for the technician to find time to come out to check the boat.

The response from the company which installed the generator intrigues me, and I would appreciate your comments:

"this unit was hooked up like the previous unit had been installed. We did not alter the wiring on the boat or generator but followed the hookup according to the previous generator.
Based on the picture attached the unit was hooked up to produce 120 volts as the previous unit was. We can tell it was 120 volt based on the wiring to the breaker."

http://i1123.photobucket.com/albums/l554/vjcast/Lilly%20Marie%20Generator/PA270243GenwireconnectionsfromtopR.jpg (http://s1123.photobucket.com/user/vjcast/media/Lilly%20Marie%20Generator/PA270243GenwireconnectionsfromtopR.jpg.html)

I understand that the generator is wired to the boat as 120v. I thought a generator set up at the factory as 120/240 had to be modified with jumpers or otherwise, within the generator before it could be wired to the boat as 120 in the manner shown in the photos. As I read the Onan diagram, I thought the four output wires for the generator should be connected as shown in the diagram with wires T-1 and T-4 connected to separate poles of the double pole breaker on the generator, rather than two wires ( T-1 and T-3) connected together to one breaker pole. I understand that with 120/240 the Hot/Load output wires would need to be kept separate, one to each of the two 30 amp panels.

http://i1123.photobucket.com/albums/l554/vjcast/Lilly%20Marie%20Generator/PA300257GeneratorDiagram.jpg (http://s1123.photobucket.com/user/vjcast/media/Lilly%20Marie%20Generator/PA300257GeneratorDiagram.jpg.html)

Is there a difference between how the generator is set up for output ( 120 vs 120/240) or is it simply a matter of how the generator is wired to the boat wiring?

The seller/installer advised the following regarding the neutral / ground connection:

"The generator is grounded at the braided strap coming out of the unit and is attached to the green wires that lead to a ground on the boat. The neutral wire (yellowish/white wire) is hooked up to an isolator (red post). The boat must have been setup to have an isolated neutral."

I have checked the connections with my multimeter and confirmed that there is no continuity between the neutral buss and the grounding buss with the shore power rotary switch turned to "generator" (with shorepower and inverter disconnected and the generator turned off)

As best I can understand, the ABYC requires a neutral / grounding connection at the generator. Did Hatteras set up their generators with an isolated neutral? ( The boat does not have an isolation transformer.)

Thanks

[Boatnut]

I still plan on letting you all know the results of the inspection by a qualified technician, but I am still waiting for the technician to find time to come out to check the boat.

The response from the company which installed the generator intrigues me, and I would appreciate your comments:

"this unit was hooked up like the previous unit had been installed. We did not alter the wiring on the boat or generator but followed the hookup according to the previous generator.
Based on the picture attached the unit was hooked up to produce 120 volts as the previous unit was. We can tell it was 120 volt based on the wiring to the breaker."

http://i1123.photobucket.com/albums/l554/vjcast/Lilly%20Marie%20Generator/PA270243GenwireconnectionsfromtopR.jpg (http://s1123.photobucket.com/user/vjcast/media/Lilly%20Marie%20Generator/PA270243GenwireconnectionsfromtopR.jpg.html)

I understand that the generator is wired to the boat as 120v. I thought a generator set up at the factory as 120/240 had to be modified with jumpers or otherwise, within the generator before it could be wired to the boat as 120 in the manner shown in the photos. As I read the Onan diagram, I thought the four output wires for the generator should be connected as shown in the diagram with wires T-1 and T-4 connected to separate poles of the double pole breaker on the generator, rather than two wires ( T-1 and T-3) connected together to one breaker pole. I understand that with 120/240 the Hot/Load output wires would need to be kept separate, one to each of the two 30 amp panels.

http://i1123.photobucket.com/albums/l554/vjcast/Lilly%20Marie%20Generator/PA300257GeneratorDiagram.jpg (http://s1123.photobucket.com/user/vjcast/media/Lilly%20Marie%20Generator/PA300257GeneratorDiagram.jpg.html)

Is there a difference between how the generator is set up for output ( 120 vs 120/240) or is it simply a matter of how the generator is wired to the boat wiring?

The seller/installer advised the following regarding the neutral / ground connection:

"The generator is grounded at the braided strap coming out of the unit and is attached to the green wires that lead to a ground on the boat. The neutral wire (yellowish/white wire) is hooked up to an isolator (red post). The boat must have been setup to have an isolated neutral."

I have checked the connections with my multimeter and confirmed that there is no continuity between the neutral buss and the grounding buss with the shore power rotary switch turned to "generator" (with shorepower and inverter disconnected and the generator turned off)

As best I can understand, the ABYC requires a neutral / grounding connection at the generator. Did Hatteras set up their generators with an isolated neutral? ( The boat does not have an isolation transformer.)

Thanks

The answer to your question is about 120 and 240 is both the generator and wiring in the boat have to be set up the same.

You might try turning off the circuit breaker, start up the generator and check the voltage at the output of the generator between the junction of T1 and T3 the junction of T2 and T4. If you do not get 120 volts which is what you should get according to the information you have posted, you could get 220 to 240 volts if you information is incorrect. Any other voltage readings under these test conditions call a generator repairman.

Rereading the thread, what comes to mind, is no matter whether you have an isolated neutral, or grounded neutral, you should get 120 volts hot leg to neutral. You indicate the transformer has T1 and T3 tied together, and T2 and T4 tied together. This configuration will produce 120 volts between the place where T1 and T3 are connected, and T2 and T4 are tied together. The isolated neutral works fine, however your polarity indicator will not work properly with an isolated neutral. The previous owner did not have a polarity indicator as I understand it, therefore there was never a problem. As I understand it this problem started with the installation of a polarity indicator. If this is true, you have added a path between neutral and ground that the isolated system does not care for. I am assuming the polarity indicator works fine on shore power. If it does then neutral and ground are tied together for shore power, but the generator has an isolated neutral. You have some choices to resolve this issue. 1. Forget the polarity indicator, 2. rewire the polarity indicator so it is out of the circuit when using generator power, 3. Have a qualified electrician check out the system and recommend how to rewire for a grounded neutral. You should be able to tie neutral and ground together at the generator, provided the boat is wired correctly.

You might try turning off the circuit breaker, start up the generator and check the voltage at the output of the generator between the junction of T1 and T3 the junction of T2 and T4. If you do not get 120 volts which is what you should get according to the information you have posted, you could get 220 to 240 volts if you information is incorrect. Any other voltage readings under these test conditions call a generator repairman.

[Boatsb]

The last sentence says it all. What make you think it was right before the new genny was installed?

[Vincentc]

The multimeter tells me the is no continuity between neutral to ground when switched to the generator with power off. The polarity lights called to my attention the fact that when running the generator the volt meter reads 69 volts hot to ground and 49 volts neutral to ground. I will try Testing voltage at the generator with the breaker off.
Better yet hope to get someone to look at it soon.
Thanks

[Vincentc]

I performed the suggested test this morning

With the generator running and it's breaker off and the ship service switch to off:

H to N. 118v
N to G. 32v
H to G. 85v

Note, I forgot about the Air conditioner panel rotary, and it was turned to generator

With the generator off and with the panel rotary switches to generator there was a reading of 260 k ohms between neutral and ground at the generator.

Regards

[Boatnut]

When you say you measured with reference to neutral at what point on the drawing are you calling neutral? If you are calling the point where T2 and T4 (refferred to as L0 in the diagram) are tied together, you most likely have an isolated neutral. The only difference between the isolated neutral, and grounded neutral, is the neutral is not tied to ground at the generator on an isolated system.

It may be prudent to investigate your shore power grounding as well. do all the same measurements you did for the generator, at the shore power panel. If you get typical readings like 120 volts between hot and neutral, and hot and ground, and less than a couple of volts neutral to ground the shore power is a grounded system. If the readings are the same as when the generator is running, you have an isolated system on the shore power system. If the shore power system is a grounded system, you can the tie neutral and ground on the generator, and solve your problem. If you find the shore power system is an isolated neutral, I suggest you have an electrician check the system out, I do not think Hatteras would put such a system in. Also be sure to check the polarity of the general ac, and be sure it is the same as the shore power, and not reversed.

I do not think a polarity indicator will properly work with and isolated neutral. I am not 100% sure on this, and it's late, and I am too lazy to check that out, call the manufacturer and ask them.

[Boatsb]

If the polarity indicator is showing. Potential between gnd and neutral there is a chance that the genny and shore power are not wired the same. Its a dumb indicator and will light up with a voltage potential. Neutral and ground should not have potential between them.

[Boatnut]

If the polarity indicator is showing. Potential between gnd and neutral there is a chance that the genny and shore power are not wired the same. Its a dumb indicator and will light up with a voltage potential. Neutral and ground should not have potential between them.

Scott, That's what it sounds like to me, if it were my system, I'd tie neutral and gound together at the generator, and see what happens. Being it's not mine, and not seeing the problem, I hesitate to make such a suggestion. I think the safest thing to do is get a qualified electrician to look at it and straighten it out.

What concerns me is the high resistance reading between neutral and ground. A visual inspection should reveal if neutral and ground are connected, it's not too hard, look and see where the wires from LO on the generator go, if they don't go to ground then that's the problem.

I would also confirm that the shore power is grounded properly as well.

[Vincentc]

It is difficult to to communicate things I do not really understand. I hope I am learning.

I am still trying to find someone with the expertise and time to come out to the boat and set it up properly. I have contacted several recommended electrician, but so far the closest I have come was a phone conversation with an electrician who kindly reviewed the situation and told me his impressions after looking at photos and my test results. He believes he understands the problem but is committed to other projects for the next few weeks.

He was concerned with the safety hazard, also said that the Neutral and Ground need to be connected at the generator and could not understand why the generator was set up with an isolated neutral.

In addition, I understood him to say that the generator could be wired with two 120v outputs by connecting:

"T1" to one side of the 40 amp double pole breaker on the generator, and attach the Hot wire of one of the 30 amp circuits to the load side of that pole:

"T4" to the other side of the 40 amp double pole breaker on the generator and attach the Hot wire of the other 30 amp circuit to the load side of that pole;

"T2" and "T3" combined and connected to ground at the generator and the Neutral wires for both 30 amp circuits to T2 and T3.

I would need to add a second breaker next to the existing breaker located near the generator (labeled "Generator No. 1) so that I would have separate breakers for each of 30 amp circuits and keep separate L1 and L2.

I am convinced there is no Neutral to Ground connection other than the connection ashore for shore power and the switched neutral ground connection which closes when the inverter is operating. I have conducted the tests using a multimeter recommended by Nigel Calder as well as the tests included with the Blue Sea installation instructions for the breaker panel and rotary switch installed for the inverter and everything is with limits except for the lack of a neutral to ground connection at the generator.

I hope to report soon regarding results of a qualified person looking at and correcting things.

Regards,

[Avenger]

I think he's describing wiring the generator for 240V and splitting the legs to get two 120Vs. The only problem with that is if one leg is loaded significantly more than the other i.e. if the Air Conditioning is all on one circuit, it loads the generator poles in an unbalanced manner which does not enhance generator life. If there are no 240V loads on the boat it's best to wire it for 120V operation.

[Vincentc]

I can see how the load would not be balanced. Glad you pointed that out. Actually the tech I spoke to did not recomend splitting the load, but answered my question, could it be done that way. Splitting sounded neater to me, but the need for a balanced load makes splitting impractical.

It seems like jumpers on both ends of the double pole 40 amp breaker on the generator would allow the hot wire load to be carried by both poles of the breaker and take care of the tripping breaker problem.

Hope to get someone to the boat soon to set up a neutral to ground connection on the generator and also take care of the breaker issue.

Thanks

[Canuck Dennis]

When we replaced my onan 7.5 with a Norpro,, we ran from the Norpro to the existing breaker mounted on the bulkhead, 2 wires from the control box to the breaker,we had to switch one internal wire to another post, this enabled the 120 V. which then fed each panel, I did not see any external wiring to grounds or otherwise.
YMMV

[Vincentc]

Dennis,
Did you connect the two green grounding wires to the generator?

Although my grounding wires are connected to the generator, there is no neutral to ground connection at the generator. As I understand it, that connection is required by the ABYC for safety reasons, not functionality.

You may want to check your wiring to see if you have continuity between neutral and ground at the main panel with the panel selector switch turned to "generator". You do this test with the shore power disconnected and the generator and any inverter OFF.

If you do not have continuity, I would be curious to know if you have voltage between the neutral/white wire bus and grounding/green wire bus at the main panel with the generator running and the panel switched to "generator".

Regards

[Boatnut]

With reference to Dennis' post and Vincent's comment in his last post. As we all know some contractors will cut cost corners wherever possible. If there truly are no ground wires to any power source, you then have what is often called a floating power source. What these guys do is tie the neutral, and ground together at the power distribution point. There is little doubt in my mind there are lots of boats out there wired this way. Yes it works, the down side of such a set up is there is no safety ground on the generator. Should anythig go wrong with the generator the case of the generator could become hot.

Ground and neutral can be very confusing. Neutral is the return leg to the power source and is a current carrying line, if wired correctly the wire color is white. The green or green wire with a yellow tracer is a safety ground and is not a current carrier. It is there to provide a lower resistance to ground to try and avoid a shock hazzard. A shock is caused because the human body is the path of least resistance, the safety ground hopefully provides a lessor path of resistance.

Not too long ago, I was introduced to a new boater at the marina. He had some work done on the boat and his wife was complaining that she would get a shock in the galley sometimes. At his request I took a look at the situation, and after about 15 minutes of diagnosing, the problem was apparent. The electrician had reversed not and neutral on one of the 120 volt circuits. The gentleman had contacted the guy that did the work, and was told his wife was nuts. Well to make a long storyshort, I have had a few go around with this guy. I went over to his shop with the owner, the guy took one dirty look at me, and then followed us back to the boat, and fixed the problem. So who the heck to people who do not know electriciy protect themsleves, it scares me sometimes.

Happy Boating Everyone,

[Canuck Dennis]

The gen set came with it's own frame, perhaps the grounding was internal at the factory during assy. the 120 v wiring was to the best of my memory, identical to the original Hatteras factory wiring of the Onan, the electrician followed the Onan wiring diag. to compare the setup. Do not have an inverter on board.
The electrician was at Owl Creek boat works, so, I assume he was competent.

[Vincentc]

I spoke to another Onan generator technician today who confirmed the thoughts expressed here and elsewhere to connect the neutral to the ground at the generator; however, he too was not available to come to the boat, so I went down to the boat this evening and did it myself.

I moved the Neutral wires over to the ground connection, secured everything together and cranked it up. It worked fine, indicated 117.5 volts between the neutral and hot at the generator, and the reverse polarity lights did not light up. I did not have time pull every thingout of the closet and check voltage at the panel.

He suggested I use two jumpers to connect the poles of the double pole 40 amp generator and split the load between the two poles to address the breaker tripping issue. I will probably try that next.

Thanks,

[Canuck Dennis]

So, you now have a hot ground ?

[Boatnut]

So, you now have a hot ground ?

Good question Dennis. First let's address Vincent's situation. Vincent, you have now established you had a generator wired with an isolated neutral. By moving the neutral to the ground connections you have brought neutral and ground to the same potential. What you did is fine, and has proven the point. It will be better and safer to reconnect the neutrals back where they were, then install a jumper wire of the same rating between the neutral and ground at the generator. This should be the only place neutral and ground should be connected.

Now for dennis' comment. Take a simple electrical device like a toaster. The plug has 3 prongs on it. One prong connected to the black wire, is the hot leg, the second prong is connected to the white wire, and is the neutral. The third prong is connected to ground. Here is the difference between neutral and ground, The current flows from the source down the black wire to the heater element, current passes through the heater element, and returns to the source on the white wire. The green wire is connected to the frame, or case of the toaster, it does not carry current. What this amounts to is if a failure in the toaster should happen, like the heating element breaks off and lays up against the case. Without the green ground wire connected to the case, the case will be hot, probably a potential of 120 volts. If the green wire is connected, you now have a short circuit to ground, which gives a lower resistance to ground than your body if you aren't standing in a pool of water. If the circuit is properly protected by the corrent size fuse or circuit breaker the fuse will open, or the breaker will trip. It is called a safety ground because it is intended to react in a manner that prevents a shock to the operator.

[Vincentc]

Dennis, Interesting point, but I don't think so.

As I understand it, a voltmeter should read voltage between hot and neutral and between hot and ground.

Since the generator no longer sets off the red reverse polarity lights and the green lights are on, I assume that there is no voltage between neutral and ground at the panel, but there is between hot and ground.

Shoreside, the neutral and ground are connected at the main panel. The inverter connects neutral and ground at the inverter while inverting. Like Nigel Calder says in his boatowner's manual: " An onboard generator has its neutral and grounding wires tied together at the generator case and nowhere else."

I typed this before seeing Boatnut's post, and would defer to his assessment.

Regards,

[Vincentc]

Boatnut,

I prefer better and safer,

How do I determine what is the same what is the "same rating"?

The two "T" generator wires leading to the Neutral post look to me about 8 or 10 ga and the Neutral connected to those wires about 4 or 6 ga.

Thanks

[Boatnut]

Vincent sorry for the confusion. I was referring to the wire size, it shoud be at least the same gauge as the hot side, one size larger never hurts.

As I have noted in the past, Calder sometimes leaves a few details out, and things to the unknowing get missed, generators do not come totally prewired and set up for specific situations, it is up to the installer to determine the setup. This is what your problem was, the neutral was not grounded, giving you an isolated neutral. It sounds like you have solved your problem. that's great. Be sure to make a final check for voltage between neutral and ground, don't ever assume with electricity, like you never assume the gun is not loaded.

Have a good day!

[Vincentc]

Thanks for your review and advice.

Good analogy.

Regards,

[Boatsb]

Vincent sorry for the confusion. I was referring to the wire size, it shoud be at least the same gauge as the hot side, one size larger never hurts.

As I have noted in the past, Calder sometimes leaves a few details out, and things to the unknowing get missed, generators do not come totally prewired and set up for specific situations, it is up to the installer to determine the setup. This is what your problem was, the neutral was not grounded, giving you an isolated neutral. It sounds like you have solved your problem. that's great. Be sure to make a final check for voltage between neutral and ground, don't ever assume with electricity, like you never assume the gun is not loaded.

Have a good day!

Every gun is loaded.

[Vincentc]

I checked voltage from the generator at the main panel. 118 volts between hot and neutral and between hot and the ac ground bus. Less than 0.1 volts between the neutral and the ground.

Making a neutral to ground connection at the generator fixed the polarity issue.

Thanks for the help.