generator wiring question

[seacolt]

Installing A 12 kw northern lights generator, The take out was the original onan 15 kw. I have hot and neutral for ship service and hot and neutral for A/C service, I'm all set and know where those wires go. My question is there are two green ground wires. Do those get grounded to neutral or to the block.
Thanks

 

[dsharp]

No they don't go to neutral. That is an equipment ground. I would double check the install manual but there should be a ground lug on the block or a lug that carries the ground to the panel. Is it a new generator?

 

[Boatnut]

First thing is, do you have an isolation transformer, if you do The green grounds should go to the transformer secondary ground stud. If no isolation transformer then locate the green wire on the incoming shore power and connect the green wires there. Do not confuse neutral with ground, they are definitely not the same. The neutral is a current carrier, the ground is a safety.

 

[Boatsb]

Marine generators have no ground. They do have a chassis ground for the dc but since there is no actual ground on the boat once the shore power is dropped there is no way to ground them for ac

 

[MikeP]

Here's a quote from the NL installation manual re AC installation as far as grounding/neutral conductor; I have no idea how our NL is installed since I didn't install it, but I found the NL statement interesting. As noted, the instructions for your specific model will have additional electrical info.

"There is no consensus of opinion on whether the neutral conductor should be connected to the bonding system (grounded) or not (floating ground). Ground-
ing the neutral may increase electrolytic corrosion. Not grounding the neutral creates a potential shock hazard. The American Boat and Yacht Council recommends grounding the neutral at the generator for safety reasons, though this may shorten the life of heat exchangers and other components. Northern Lights heartily recommends grounding the neutral since personal safety takes priority over all other considerations.
For additional electrical information, consult the AC wiring diagrams in the Generator Manual for the generator end installed on your set."

 

[bostonhatteras]

Marine generators have no ground. They do have a chassis ground for the dc but since there is no actual ground on the boat once the shore power is dropped there is no way to ground them for ac

believe me, Im not trying to step on any toes, but isn't that what the ground plane is for? inside all the electrical panels the neutral and ground lines are held separate however there is a common connection between them at the ground plane (dynaplate, grounding plate). This ground plane also has a connection to the dc negative lugs and bonding system. I believe that to fully isolate the generator neutral is virtually impossible because of all the other connections around it so any electrolytic action presented by the genset is almost impossible to remove. I have the gensets block tied to the bonding system and as mentioned because of the ultimate neutral connection to the ground plane, so is the neutral. I don't have much of a electrolytic or galvanic corrosion issue at all zincs last an entire season easily what I do have though is serious cables leading all return path electricity back to the batteries etc so that is the easiest route of return and not through shafting etc which does kill zincs. the return path is as or more important than the lead path for electricity in my opinion. same goes for a continuous and uniform bonding system.

 

[Boatsb]

believe me, Im not trying to step on any toes, but isn't that what the ground plane is for? inside all the electrical panels the neutral and ground lines are held separate however there is a common connection between them at the ground plane (dynaplate, grounding plate). This ground plane also has a connection to the dc negative lugs and bonding system. I believe that to fully isolate the generator neutral is virtually impossible because of all the other connections around it so any electrolytic action presented by the genset is almost impossible to remove. I have the gensets block tied to the bonding system and as mentioned because of the ultimate neutral connection to the ground plane, so is the neutral. I don't have much of a electrolytic or galvanic corrosion issue at all zincs last an entire season easily what I do have though is serious cables leading all return path electricity back to the batteries etc so that is the easiest route of return and not through shafting etc which does kill zincs. the return path is as or more important than the lead path for electricity in my opinion. same goes for a continuous and uniform bonding system.

All boats should get a ground through the shore cord which is why its wired that way. the ground plane gas no connection when shore power is not attached.

If your vessel is wired for the ground and neutral to be separate keep it that way. ...

 

[Pascal]

If I remember correctly, marine inverters bond neutral to ground when in inverter mode. in pass thru or charger mode, they release the neutral to ground bond because it is handled at the source, either shore power or generator.

This is discussed in detail in Magnum inverter installation instructions. I don't recall how the bonding is done at the generator but neutral and ground are connected there.

Some appliances also bond N to G by default, like stoves and possibly even fridges. When I replaced the old stove/oven on my boat with a new one, I disconnected the factory jumper between N and G

 

[bostonhatteras]

All boats should get a ground through the shore cord which is why its wired that way. the ground plane gas no connection when shore power is not attached.

If your vessel is wired for the ground and neutral to be separate keep it that way. ...

"the purpose of the various normally non-current carrying grounding systems is to provide a path to ground WITHIN THE BOATS WIRING for ac fault currents, stray currents, and lightning. in order to do this it is NOT necessary to have separate ac grounding, bonding and lightning conductors fastened to all major metal objects-in theory the same conductor can serve all three purposes, as long as it is rated for the job. However, in practice the ac grounding cable is always run as a separate circuit to all ac outlets and appliances, terminating at the ac grounding bus, from where a connection is made to the common ground point or bus bar."

"another grounding point or bus bar should be established as the boats COMMON GROUND POINT. all the non current carrying grounding conductors are fastened to this bus, including
-a connection to the dc negative bus
-the grounding wire green or bare from the ac distribution panel (but never the neutral wire)
-the lightning/binding circuit
-ground connections to radio ground plates
-external ground plate or strip
-any zincs for cathodic protection

from nigel calders boat owners...manual

so yes, there is still an emergency/safety ground for the ac system once you leave the dock. my apologies for confusing the issue with my 'ultimate neutral connection' comment, as I mean to say simple things like a toaster oven or space heater can make that ground/neutral connection inadvertently, as well as block heaters etc. for the record I do believe that the neutral should be maintained as isolated as possible just as the hot is. it is just difficult to find every single point where there may be a connection between the neutral and ground

 

[Boatnut]

Not trying to offend anyone here, but let's try and not confuse everyone. There is a little saying that goes "ground is ground, the world around, everything refers to ground". This can be looked at like this, in the electrical world anything not grounded carries an electrical potential.

When the neutral becomes involved is where the conntroversy begins. The green ground wire is refered to as a safety ground. It is not ment to carry current in normal operation, it is always tied to case and/or chassis ground. What this means is if any electrical part in the appliance inadbertantly touches the case, or cover which can be a metal cover or gaurd, the saftey ground is a better conductor that a human. In theory this should prevent a shock in this situation.

The only place ground and neutral are connected is at the source. That connection is done by the power company. In a lot of cases you will find that the neutral and gound are tied together at the incoming power box. I have seen where installers tie ground and neutral together at the dock box. This works as does tying them together at the power panel on the boat. Some agree with this others do not. The bottom line is, in the system there should be only one place where neutral and ground are tied together and that is at the source. All ground wires go directly to the ground bus, all neutals go to the neutral bus. We all know that in marinas lots of short cuts are taken, check things out do not assume the marina is correctly wired.

Grounding is a science in itself, and is extremely complicated, so don't let it get to you, and don't be afraid to ask questions if it does confuse you. It's is your family, friends, and yourself you are protecting.

Now just to be a pain in the butt, lets look at those vessels with 220 coming aboard. Unless you are using a 4 conductor power cable and the marina is wired for 4 conductor, neutral is not brought aboard. Most of the boats we have being of older quality vintage do not bring neutral aboard. In this case neutral is developed on board. The only reason we need neutral is to develope 120 volts. It appears that most of the Hatts using 220 also have isolation transformers, in which case there is no need to bring neutral aboard, the neutral is developed in the secondary of the transformer.

I hope this will help, and I did not bore anyone too badly. This junk is dry and boring to read or listen to.

Happy Cruising

 

[Boatnut]

If I remember correctly, marine inverters bond neutral to ground when in inverter mode. in pass thru or charger mode, they release the neutral to ground bond because it is handled at the source, either shore power or generator.

This is discussed in detail in Magnum inverter installation instructions. I don't recall how the bonding is done at the generator but neutral and ground are connected there.

Some appliances also bond N to G by default, like stoves and possibly even fridges. When I replaced the old stove/oven on my boat with a new one, I disconnected the factory jumper between N and G

I believe that the neutral and ground were tied together for 220v operation, to use 120v you would seperate them. I hope you checked to insure you have a good ground connection to the source ground.

 

[gbharrington]

Not bored at all, just fascinated. So much to learn.
In regards to "connected at the source". Is the generator considered a source when the boat is disconnected from shore power?

 

[Boatsb]

Not bored at all, just fascinated. So much to learn.
In regards to "connected at the source". Is the generator considered a source when the boat is disconnected from shore power?

Maybe


Not every boat is wired the same and changing the method is more dangerous than you think. If it has a ground to the genny from the factory see where it goes. Mine did not have one. L1, L2 and C were the original design.

as for not carrying C ( neutral ) in 220 systems that is true but a 120/240 system has it.

 

[Pascal]

.
.

Now just to be a pain in the butt, lets look at those vessels with 220 coming aboard. Unless you are using a 4 conductor power cable and the marina is wired for 4 conductor, neutral is not brought aboard. Most of the boats we have being of older quality vintage do not bring neutral aboard. In this case neutral is developed on board. The only reason we need neutral is to develope 120 volts. It appears that most of the Hatts using 220 also have isolation transformers, in which case there is no need to bring neutral aboard, the neutral is developed in the secondary of the transformer.



Happy Cruising

I don't think this is accurate. Every shore power hook up brings neutral and ground onto the boat. In case of the 120/220-50 shore power found on most boats, you have two hots on opposing phase, a neutral and a ground, always 4 wires.

 

[Boatsb]

I don't think this is accurate. Every shore power hook up brings neutral and ground onto the boat. In case of the 120/220-50 shore power found on most boats, you have two hots on opposing phase, a neutral and a ground, always 4 wires.

No. 220 service can and is used often. especially where buck boost transformers are inline. The transformer makes the C ( neutral ) from the 2 legs and the ground does not pass direcdtly but through the transformer circuit.

Ever see 100 amp service? 200 amp service, 208 V 3 phase or higher voltage services?

 

[seacolt]

Dsharp, The gererator is new to me but not new. 230 hours, looks and run excelent. Your comments have been very heplfull, I am much more versed on the DC system than the AC. I'm now A step closer knowing more about my AC system. The reason I posted was because the northern lights technical rep asked how it was set up with the old generator ( I did not disconnect the wiring). However, I now have a clear understanding that the ground wires will be connected to the grounding lug on the generator.
I'm taking this one step at A time. I still have to deal with the wires that were tied into the breaker pannel (start, preheat, indicator lights) I'm pretty sure i'm eliminating those because the Northern Lights has its own pannel. And the last piece of the puzzle is installing a new 3 position (without bypass) rotary selector switch so I can still use my inverter.
Thanks for all the great information

 

[Pascal]

No. 220 service can and is used often. especially where buck boost transformers are inline. The transformer makes the C ( neutral ) from the 2 legs and the ground does not pass direcdtly but through the transformer circuit.

Ever see 100 amp service? 200 amp service, 208 V 3 phase or higher voltage services?

We re talking small to mid size boats here, not mega yachts with 100amp service...let s keep it relevant.

As I said, the standard 120/240-50 service found on most boats in the size range we all own or are familiar with use 4 wire shore power that includes neutral.

Now, depending on the transformer config, the neutral may or may not be used but it will be brought on board

 

[Boatsb]

I don't think this is accurate. Every shore power hook up brings neutral and ground onto the boat. In case of the 120/220-50 shore power found on most boats, you have two hots on opposing phase, a neutral and a ground, always 4 wires.

Your words not mine

 

[Boatnut]

The size of the boat has nothing to do with whether or not neutral is brought aboard.

The way the boat is wired would determine how many conductors are required. On a boat using 220v without an isolation transformer should have the neutral coming in from the dock. That would be the most correct, and safest way to do it. Also note that bringing hot and neutral on board, can also cause electrolysis problems. Fortunately there is a simple fix for this problem. On a boat with an isolation transformer neutral may be brought aboard, however it is not used, unless some fool decides he wants 120v to be developed on the source side of the transformer. Neutral using an isolation transformer is developed in the secondary of the transformer.

The question about is the generator ground the answer is, when not connected to any outside source, meaning no wires connected to the boat, whether the power switch is on or off, then the generator would be the source. Ground is never switched.

 

[Canuck Dennis]

I think Pascal may be confusing two 120v services coming in which may be classified as 240 into the boat which would be 4 wire although not a true 240. My 70 has 240 2 wire service , neutral created by the tsfrmr.