Floating boat docks personal not commercial

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Johnnewcomb62

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Location
Arley, Alabama
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Electrical Contractor
Hello all,

I have recently moved to a new home semi retiring on a lake but am still actively working and have run into an issue I can't find much information on so I am posting this to see if anyone knows the correct way to go about these situations I have encountered since moving here.
First of all we are really out in the country and there is no inspectors or inspections on anything out here which is very concerning to say the least. But the main issues out here of course are the boat docks which this lakes level goes up and down so everyone has floating type boat docks here. I have looked at a few since I have moved here and NONE of them are grounded as code requires with the #6 wire going from all metal parts back to the originating source or at least that is how I read it. The current folks working on the docks out here have said that if you do that it will energize the dock. The electric company out here sometimes and in some places the way I understand it will actually have a voltage on the ground so if you ground the dock structure you will be actually energizing the structure so they all isolate all the circuits as to have none of the metal parts grounded. Which again is very concerning to me. So I have steered away from working on these since if you do it according to code everyone is saying it will create a shock hazard for the owner and if we isolate the circuits as everyone else is doing and they have a fault then we of course will get sued I'm sure for not doing the job as code requires.
So my question is am I totally wrong in thinking that they should be grounded as code states or is there some exception or none requirement that I am missing or don't understand. I don't really know how the power companies supply somehow energizes the ground wire from time to time but it is happening and just was wanting someone with more knowledge than me to maybe tell me how we can do these under these circumstances where most of all no one gets hurt and of course a lawsuit isn't a major threat ?

Thanks in advance
John Newcomb
 
Almost all electric supply systems have neutral to earth voltage (NEV) and anything connected to the electrical grounding system will have that voltage as measured to remote earth, often defined as earth at least 50' from any grounding electrode. In most cases this voltage is not enough to be any type of a hazard, but in the water it could be. The dock is different from a pool. At the pool we bond and energize everything that you can touch, including the water. Since you can't touch anything that is not energized at the same voltage, there is no potential difference.
That can't happen at a dock because you can't energize that water to make it a zero potential like you can in a pool.

Yes, the code requires bonding at the docks, and there is no real solution other than not permitting anyone in the water anywhere near any dock that has electric power run to it. That is way 555.10, in the 2020 and 2023 code, and 555.24 in the 2017 code requires a warning sign that reads
“WARNING — POTENTIAL SHOCK HAZARD — ELECTRICAL CURRENTS MAY BE PRESENT IN THE WATER.”
Click to expand...

Note it is my opinion that the code required language does not go far enough. It should have additional language telling you to stay out of the water.
 
OK we know that we can't stop the voltage being on the ground wire and if the ground has to be attached to all the metal parts of the dock therefore energizing the dock and we definitely don't want that how about this.
Install a 3-phase disconnect onshore before the walkway to the dock and break all the leads including the ground wire and instruct the owners to cut off disconnect before entering the water which would effectively disconnect everything going out on the dock so there would be no power leads or grounds connected so it would be like no power is going to dock at that point and we could post signs on the dock and at the ladder saying no one in the water without cutting off the disconnect. ???
 
Johnnewcomb62 said:
OK we know that we can't stop the voltage being on the ground wire and if the ground has to be attached to all the metal parts of the dock therefore energizing the dock and we definitely don't want that how about this.
Install a 3-phase disconnect onshore before the walkway to the dock and break all the leads including the ground wire and instruct the owners to cut off disconnect before entering the water which would effectively disconnect everything going out on the dock so there would be no power leads or grounds connected so it would be like no power is going to dock at that point and we could post signs on the dock and at the ladder saying no one in the water without cutting off the disconnect. ???
Click to expand...

That disconnect will likely rust in the closed position for lack of use.
 
YES I believe you are more than likely correct in saying that but my position is, then, they would be doing it to themselves. I would like to make sure that the situation wouldn't be against any codes because I absolutely know it would be safe if used as directed.
I just want to make sure if I wire a dock here that it is absolutely safe ( if used as directed ) and that it is code as well.
 
Johnnewcomb62 said:
Hello all,

I have recently moved to a new home semi retiring on a lake but am still actively working and have run into an issue I can't find much information on so I am posting this to see if anyone knows the correct way to go about these situations I have encountered since moving here.
First of all we are really out in the country and there is no inspectors or inspections on anything out here which is very concerning to say the least. But the main issues out here of course are the boat docks which this lakes level goes up and down so everyone has floating type boat docks here. I have looked at a few since I have moved here and NONE of them are grounded as code requires with the #6 wire going from all metal parts back to the originating source or at least that is how I read it. The current folks working on the docks out here have said that if you do that it will energize the dock. The electric company out here sometimes and in some places the way I understand it will actually have a voltage on the ground so if you ground the dock structure you will be actually energizing the structure so they all isolate all the circuits as to have none of the metal parts grounded. Which again is very concerning to me. So I have steered away from working on these since if you do it according to code everyone is saying it will create a shock hazard for the owner and if we isolate the circuits as everyone else is doing and they have a fault then we of course will get sued I'm sure for not doing the job as code requires.
So my question is am I totally wrong in thinking that they should be grounded as code states or is there some exception or none requirement that I am missing or don't understand. I don't really know how the power companies supply somehow energizes the ground wire from time to time but it is happening and just was wanting someone with more knowledge than me to maybe tell me how we can do these under these circumstances where most of all no one gets hurt and of course a lawsuit isn't a major threat ?

Thanks in advance
John Newcomb
Click to expand...
Voltage drop on the MGN (multi grounded neutral), including the service neutral to your premises.

If you have 7200 volts primary with one of the conductors being the grounded neutral of the primary, and that conductor happens to be carrying enough current to cause a 1.5 volt drop at your service transformer (relative to earth potential) that grounded primary conductor is bonded to the secondary grounded conductor (usually a neutral conductor on majority of systems) that brings that 1.5 volts to earth to everything bonded to the grounded service conductor - which includes any EGC's or other bond conductors you land there. Driving ground rods helps in the immediate vicinity of the rod(s) but they are never low enough resistance to shunt all if it away, so anything you bring to the dock that ultimately connects to the service neutral also has this 1.5 volts to earth on it.

Any voltage drop on your service neutral is also added to the volts to earth.

If a conductor is carrying current it will have a voltage drop across it, that you can't change. You can change how much drop there is by changing the amount of current flowing or by changing conductor resistance (changing size) but there will always be some drop as long as current flows on the conductor.

GFCI's won't protect you from this, they don't care what is flowing on the EGC. they only monitor the hot(s) and neutral of the circuit they are protecting and trip when enough of that current is leaking to outside of the protected protected conductors.
 
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