Neutral to Ground Voltage @ Boat Lift

Status
Not open for further replies.
kwired said:
Try telling that to the family of someone that has been electrocuted. Their relative is just as dead either way.
Click to expand...
In the other scenario you described we would be using the phrase "their relatives are dead".
 
kwired said:
I am willing to guess that the non publicly owned POCO's are the ones that are more likely put off any investigation because of what it may cost in preference of profits.
Click to expand...
And these are, in turn, regulated by publicly-controlled bodies. Even the greedy for-profit POCOs have to comply with regulations. They are less prone to fuss about it because they just pass along the cost and say "hey, we have to comply with the safety rules as dictated by the regulators". As long as they make reasonable use of the investments, they are given a reasonable rate of return on their investments.

They will make the system as safe as the regulator-allowed investments will allow. They generally will not invest in above-and-beyond safety investments where the regulators do not allow for a ROI.
 
kwired, you are correct, the neighbor that shares the same transformer does have the exact same voltage between his boat lift and the water. He has driven a ground rod into the sandy bottom in the salt water at his lift motor and is ok with that. I am still not convenced that that is how I want to deal with this problem. I have entertained the thought of visiting the 20 or so neighbors with my meter and a notepad and then asking if they would mind if I check the voltage between their boat lifts and the water. After reading the same voltage I could say thank you very much and let the cards fall where they fall however, thats not my style. I just want to have a clear conscious and know that I have done every thing I could do to eliminate this neutral to ground voltage.
 
Thanks guys! The information you shared on stray voltage has helped me to better understand the animal that I am up against. I spoke with the owner of the boat lift yesterday & he says that when he was in the water last weekend he felt the same shock at the aluminum lift beam now as what he felt before the bare bond wire was installed a couple of weeks ago. I havent had a chance to put a meter on it but I know that when I bonded the motor to the water the voltage droped abot 1/2. I bet with the salt water in contact with the wire and corrosion, its back where it was originally. I was wondering about the idea of installing a small transformer to get away from the utility grounded neutral. If I do that I would still have to deal with the EG. Not so sure how thats gonna get rid of the voltage Im seeing coming of the grounded motor frame. I saw where MH appeared to share the same disgust over this problem with swimming pools as I am experiencing with the boat lift located over water.
 
rutsd said:
Thanks guys! The information you shared on stray voltage has helped me to better understand the animal that I am up against. I spoke with the owner of the boat lift yesterday & he says that when he was in the water last weekend he felt the same shock at the aluminum lift beam now as what he felt before the bare bond wire was installed a couple of weeks ago. I havent had a chance to put a meter on it but I know that when I bonded the motor to the water the voltage droped abot 1/2. I bet with the salt water in contact with the wire and corrosion, its back where it was originally. I was wondering about the idea of installing a small transformer to get away from the utility grounded neutral. If I do that I would still have to deal with the EG. Not so sure how thats gonna get rid of the voltage Im seeing coming of the grounded motor frame. I saw where MH appeared to share the same disgust over this problem with swimming pools as I am experiencing with the boat lift located over water.
Click to expand...

The fact that the EGC is connected to the utility neutral is the problem. Anything that you add must still have EGC and the problem will not go away. As I have been saying all along it is likely a POCO issue and if they will not do anything about it you need to threaten legal action, getting neighbors in on this if they have same problem will help. If the voltage is still there with the service turned off but goes away when you disconnect the incoming grounded conductor at the service it is coming from ahead of the service.

If you can determine this is what is happening and people are getting shocked, I don't see how POCO can ignore it.

Bonding the water only equalizes voltage for a small area around the bonding point. The bigger or taller you are the more likely you can reach different points of potential as there will be different voltage zones around the bonding point.

My opinion until POCO fixes problem is to disconnect the boat hoist including the EGC from the on shore structure it is served from. If POCO will not fix it maybe install a 12VDC motor for the hoist but make sure you do not have the premises EGC connected to it in any way.

--------------------

As far as POCO passing on costs, that has nothing to do with the safety issue here. All businesses have to pass on costs to customers. This is just as much about safety of public as is putting high voltage conductors at pole tops to keep them out of reach of general public. They pass cost of having to do that on as well.
 
kwired said:
The fact that the EGC is connected to the utility neutral is the problem. Anything that you add must still have EGC and the problem will not go away. ...
Click to expand...
You can install a code compliant and safe system that will make this problem go away with a creative application of 250.110 as I stated in an earlier post.
 
kwired said:
...

My opinion until POCO fixes problem is to disconnect the boat hoist including the EGC from the on shore structure it is served from. ...
Click to expand...
So now when there is a fault on the bolt lift we will energize the metal parts as measured to the water with a fatal amount of voltage as opposed to the few volts it is now energized with!!!
 
Creative & Safe Application of NEC 250.110

Creative & Safe Application of NEC 250.110

Ok, How would you connect or not connect the equipment grounding conductor to the lift equipment & solve the whole problem while complying with the requirements of the NEC?
While troubleshooting, with the main at the service in the off position, I removed the grounded conductor from the circuit going to the lift sub-panel and still read the voltage from the EGC @ the sub panel to the water. I understand that they are tied together at the service. I dont see how I will safely utilize my EGC at my new transformer.. Please explain your idea!
 
don_resqcapt19 said:
So now when there is a fault on the bolt lift we will energize the metal parts as measured to the water with a fatal amount of voltage as opposed to the few volts it is now energized with!!!
Click to expand...

I said to disconnect the boat lift including the EGC, meaning make it inoperable, as well as open the source of the stray voltage on the frame by disconnecting the EGC. If you disconnect everything but the EGC you still have the stray voltaage.
 
don_resqcapt19 said:
You can install a code compliant and safe system that will make this problem go away with a creative application of 250.110 as I stated in an earlier post.
Click to expand...

All I see in 250.110 is exception 3, but it would require a listed boat hoist with a double insulation system and be distinctively marked. Can you tell us how you would do this and comply with 250.110?

Only other thing to do is design a boat hoist with no exposed metallic surfaces that will require grounding. Hard to do if you are going to have electric power on it. Even insulating coatings will deteriorate and be a hazard eventually.
 
kwired, I undersood what you were saying about disableing the entire circuit. This is not exactly what I wanted to hear but it is the safest solution for this particular situation. I have been in the electrical industry for 25 years and havnt been exposed to stray voltage. I hate to admit it but this troublesome situation has been very edcational for me. Thanks to all you guys for helping me better understand whats going on here.
 
110604-0850 EDT

rutsd:

I did not understand your post #23 because there was insufficient information.

The one neighbor that did some sort of grounding to the earth near his boat lift reduced the voltage difference between the water and the lift to what voltage?


To other readers:

If you use a GFCI breaker on the circuit that feeds the boat lift, then can you use an isolation transformer and break the EGC conductor between the main panel and the boat lift. In this case the EGC on the secondary of the isolation transformer would be connected to that secondary and a ground rod at the boat lift.

If you have a very well insulated isolation transformer (separate bobbins for primary and secondary and epoxy encapsulated), probably identified as a double insulated device, then can this satisfy NEC with a separated EGC?

How does the NEC treat a battery charger? Does one of the output leads have to be connected to the EGC? If not, then a battery charger, to battery, to a DC boat lift motor might be considered.

Another possibility. A motor remote from the lift and coupled to the lift thru an insulated coupling, drive shaft, or belt. Now there is no conductive connection from the motor to the lift and the lift can be locally grounded.

.
 
I would use a 240 to 240/120 volt transformer without any connection to the utility grounded conductor. There would be a system bonding jumper and grounding electrode on the secondary side of the transformer. The transformer would have to be installed in a manner that would permit it to not have a connection to the service grounded and grounding conductors and that would be the application of 250.110.
 
gar said:
...

If you use a GFCI breaker on the circuit that feeds the boat lift, then can you use an isolation transformer and break the EGC conductor between the main panel and the boat lift. In this case the EGC on the secondary of the isolation transformer would be connected to that secondary and a ground rod at the boat lift.
.
Click to expand...
In general there will still be an connection to the utility grounded conductor via the primary EGC. This is where you have to use a provision that exists in 250.110.
 
gar said:
110604-0850 EDT

rutsd:
To other readers:

If you use a GFCI breaker on the circuit that feeds the boat lift, then can you use an isolation transformer and break the EGC conductor between the main panel and the boat lift. In this case the EGC on the secondary of the isolation transformer would be connected to that secondary and a ground rod at the boat lift.
Click to expand...

Gar if you have a transformer after a GFCI it renders the GFCI useless, the secondaries will only produce line to line current for any line to EGC faults on the secondaries.
 
gar, I have not personally put my meter on the neighbors lift beam that is connected to the grounded motor but the neighbor told me that he noticed the voltage problem approx. 2 years ago and he decided to bond his lift motor with a piece of copper wire and attach that to a rod which is in the water. He says that the rod is now corroded and is not as effective, He plans to replace the rod and its connection. I will have to ask him when I am there next but he doesnt seem to be concerned with the amount of voltage he is seeing. I will report back with voltage readings.
 
rutsd said:
gar, I have not personally put my meter on the neighbors lift beam that is connected to the grounded motor but the neighbor told me that he noticed the voltage problem approx. 2 years ago and he decided to bond his lift motor with a piece of copper wire and attach that to a rod which is in the water. He says that the rod is now corroded and is not as effective, He plans to replace the rod and its connection. I will have to ask him when I am there next but he doesnt seem to be concerned with the amount of voltage he is seeing. I will report back with voltage readings.
Click to expand...

If the neighbor only noticed the voltage between the boat hoist and water from being on boat or hoist this rod may have helped some but for someone actually in the water they have the ability to reach farther voltage zones around the rod and will experience higher voltage across their body.

You do not have this problem with a properly designed swimming pool beacuse unlike a river or lake, the pool has a grounded rebar cage all around it and just about any metallic equipment in or near the pool is also bonded to the same point as the cage.
 
kwired said:
...
You do not have this problem with a properly designed swimming pool beacuse unlike a river or lake, the pool has a grounded rebar cage all around it and just about any metallic equipment in or near the pool is also bonded to the same point as the cage.
Click to expand...
This problem is the reason the code added the perimeter bonding requirement a few cycles ago. Prior to this the bonding connection energized the water and there was a potential between the unbonded deck and the water.
However, there is no type of bonding or grounding that will solve the issue that is being addressed in this thread.
 
Status
Not open for further replies.
Top