Residential dock grounding

[kwired]

Second building or other structures supplied by a feeder have required both an EGC run with the feeder and a grounding electrode conductor connecting the EGC to a grounding electrode at the second building or structure. They are not separate grounding systems as the feeder EGC is connected to the main building grounding electrode system via the main bonding jumper.
Also the connection to earth does not keep points at ground potential. Typically there is a voltage on the neutral as a result of various voltage drops, and all that happens when you connect that to a grounding electrode is that the voltage of the earth is raised, in a small area around the grounding electrode, to match the voltage on the neutral.

That is what I been trying to emphasize with most my replies in this thread.

NEC needs to step up and come up with better solution then they have for these applications. Swimming pools and equipotential bonding required in those applications is good, but is impractical in large bodies of water. Some sort of method of isolating the system that supplies the dock would be better and still having ground fault protection on some level would enhance it even more. Ungrounded systems could maybe work, capacitance could maybe present problems though which is one advantage of still having grounded system, but need to find a way to isolate it from the regular premises grounding network. Easier said if dock is remote from rest of the regular premises but if you have building pretty much right close to the water it may get more complicated at assuring you keep things isolated.

 

[JB85]

I'm going to get that made up next time im there. I figured it should be but just wanted to check and make sure it wasn't something weird with it being a dock. I'm guessing it was just incorrect with the previous owner

And I guess my wording should have been same potential not ground potential

GFCI and GFPE both will not detect voltage rise in the EGC. They only trip if the protected conductors (L1, L2, L3, N) have leakage to something not connected to the protection device(EGC or anything with continuity to it or true ground, other circuits is possible but probably not so common especially in this application) that exceeds the trip threshold. Neutral to earth voltage incoming via the grounded service conductor through the main bonding jumper then out to the dock via the EGC of just 2-5 volts can be deadly to someone in the water that touches any part of the dock that is at that potential. If said voltage is much higher they may not even need to touch it, just need to be too close while in the water and end up across a voltage gradient in the water and might become incapacitated and can not move out of said gradient. GFCI/GFPE won't detect this, and won't disconnect it even if you manually turn off the feeder breaker, you need to open the EGC to make this go away, hence the problem with current NEC requirements not addressing this issue, or at least not addressing them sufficiently. Warning signs isn't enough, people ignore them for various reasons, even those that may understand the hazard pretty well may still ignore them in some cases. Thing is you often don't know there is any problem in these applications until there has been an injury or death.

I'm not trying to be argumentative but im not seeing where current flow back to the dock is likely in regards to a neutral issue. I have been on several calls in the utility side where we had an OPEN neutral, the concentric on direct buried wire was corroded apart, and that neutral current was now flowing on a separate ground path, water line, phone line, chain link fence etc, I just can't see that scenario causing a dock to become energized. We know electricity takes all paths, the amount in each path being proportionate to the resistance in each path, I would bet money the utility system neutral has far less resistance than a body of water. I'm not disagreeing with you that there could be SOMETHING there, just thinking what we have now is best practice. People are not going to quit swimming off their docks. Id rather be at a floated potential in the water and have the dock at as close to the same potential than to be at a floated potential in the water and have the dock energized bc the egc is separated from the system. Yes, a ground fault device of any kind doesn't see a rise on egc. But when it doesn't see the same current on the neutral as the line, where does it assume that current went? I'm not sure what the absolute fail proof solution is.... maybe some kind of single pole breaker special to this application that breaks the egc if it sees any voltage difference on both sides of the breaker?? It would also have to clear all source breakers as well? I don't know. Again not being argumentative and appreciate the discussion.

Also to add, I've heard of some lakes going to solar power only on docks. No permanent power at all. Maybe this is why

 

[don_resqcapt19]

That is what I been trying to emphasize with most my replies in this thread.

NEC needs to step up and come up with better solution then they have for these applications. Swimming pools and equipotential bonding required in those applications is good, but is impractical in large bodies of water. Some sort of method of isolating the system that supplies the dock would be better and still having ground fault protection on some level would enhance it even more. Ungrounded systems could maybe work, capacitance could maybe present problems though which is one advantage of still having grounded system, but need to find a way to isolate it from the regular premises grounding network. Easier said if dock is remote from rest of the regular premises but if you have building pretty much right close to the water it may get more complicated at assuring you keep things isolated.

It is my opinion that bonding any metal parts in contact with large bodies of water should be prohibited. That only serves to energize the water around the bonded metal parts creating a possibility of a dangerous voltage gradient in the water.

 

[JB85]

It is my opinion that bonding any metal parts in contact with large bodies of water should be prohibited. That only serves to energize the water around the bonded metal parts creating a possibility of a dangerous voltage gradient in

 

[kwired]

And I guess my wording should have been same potential not ground potential

I'm not trying to be argumentative but im not seeing where current flow back to the dock is likely in regards to a neutral issue. I have been on several calls in the utility side where we had an OPEN neutral, the concentric on direct buried wire was corroded apart, and that neutral current was now flowing on a separate ground path, water line, phone line, chain link fence etc, I just can't see that scenario causing a dock to become energized. We know electricity takes all paths, the amount in each path being proportionate to the resistance in each path, I would bet money the utility system neutral has far less resistance than a body of water. I'm not disagreeing with you that there could be SOMETHING there, just thinking what we have now is best practice. People are not going to quit swimming off their docks. Id rather be at a floated potential in the water and have the dock at as close to the same potential than to be at a floated potential in the water and have the dock energized bc the egc is separated from the system. Yes, a ground fault device of any kind doesn't see a rise on egc. But when it doesn't see the same current on the neutral as the line, where does it assume that current went? I'm not sure what the absolute fail proof solution is.... maybe some kind of single pole breaker special to this application that breaks the egc if it sees any voltage difference on both sides of the breaker?? It would also have to clear all source breakers as well? I don't know. Again not being argumentative and appreciate the discussion.

Also to add, I've heard of some lakes going to solar power only on docks. No permanent power at all. Maybe this is why

I can go almost anywhere around here and drive an isolated probe into the ground and measure to any object bonded to the electrical system grounding network, whether it be some branch circuit EGC or the bare wire running down a utility pole to ground rod at the pole and will likely measure a volt or two and sometimes even more. That volt or two most of us do not feel when wearing shoes and touch with calloused hands, we are insulated well enough through those points that any current that flows is so low we do not feel it.

Now submerse yourself in a body of water and you greatly increase conductivity through your skin 2 volts can be felt pretty easily, and possibly is even pretty uncomfortable. Metal dock in contact with the water, maybe is not going to be a problem it will raise the voltage in the surrounding water and you maybe only subjecting yourself to a few millivolts. But should you touch some object that is at same potential as EGC but is not also touching the water while you are in the water you are subject to that full two volts. There are reports of electrocutions at docks and similar every summer season and many of them are because of voltage rise on the EGC because of either bad neutral or because of voltage drop on a neutral which is otherwise deemed normal. Like I said with swimming pools the required equipotential bonding simply puts everything you can touch while in the pool at same potential, even if it is 100 volts to true earth and this neutral to earth voltage is not a problem at pools unless you have holes in your equipotential bonding. But with larger bodies of water is too impractical to do that bonding. Is too difficult to bring the water up to same potential as objects that have connections to other potential.

 

[JB85]

I can go almost anywhere around here and drive an isolated probe into the ground and measure to any object bonded to the electrical system grounding network, whether it be some branch circuit EGC or the bare wire running down a utility pole to ground rod at the pole and will likely measure a volt or two and sometimes even more. That volt or two most of us do not feel when wearing shoes and touch with calloused hands, we are insulated well enough through those points that any current that flows is so low we do not feel it.

Now submerse yourself in a body of water and you greatly increase conductivity through your skin 2 volts can be felt pretty easily, and possibly is even pretty uncomfortable. Metal dock in contact with the water, maybe is not going to be a problem it will raise the voltage in the surrounding water and you maybe only subjecting yourself to a few millivolts. But should you touch some object that is at same potential as EGC but is not also touching the water while you are in the water you are subject to that full two volts. There are reports of electrocutions at docks and similar every summer season and many of them are because of voltage rise on the EGC because of either bad neutral or because of voltage drop on a neutral which is otherwise deemed normal. Like I said with swimming pools the required equipotential bonding simply puts everything you can touch while in the pool at same potential, even if it is 100 volts to true earth and this neutral to earth voltage is not a problem at pools unless you have holes in your equipotential bonding. But with larger bodies of water is too impractical to do that bonding. Is too difficult to bring the water up to same potential as objects that have connections to other potential.

I agree with that. I think thats why they stress EVERYTHING in contact with water to be bonded to egc. Most of those electrocutions I hear about are from unbonded swim ladders

 

[kwired]

I agree with that. I think thats why they stress EVERYTHING in contact with water to be bonded to egc. Most of those electrocutions I hear about are from unbonded swim ladders

IMO an unbonded swim ladder especially if not bolted to something conductive on the dock will simply be at same potential as the water assuming it is in contact with the water. A bonded ladder that is in contact with the water will have a voltage gradient surrounding it in the water. Size of voltage zones is probably larger than it is around a ground rod in soil and if there is only a couple volts a swimmer maybe has little issues because they aren't crossing high enough voltage, start getting 10 or more volts on the ladder and users will probably be getting shocked. Should the ladder or other object not be in contact with water or sometimes is sometimes isn't in contact can probably be the most dangerous situation because if you are in the water you are at earth potential, you reach out and touch that object and you are subject to full voltage of whatever it is above earth potential. That two volts that didn't hurt you with a ladder in the water because the nearby water had a more gradual gradient over distance is now a full two volts when you touch it. That may not kill you but is likely pretty uncomfortable. If it is 10 volts or more your chance of electrocution is much higher.

 

[JB85]

The ones around here are bolted to the metal frame of the dock and hinge out of the water when not in use and require a grounding jumper

 

[tortuga]

GFCI and GFPE both will not detect voltage rise in the EGC.

Agreed

They only trip if the protected conductors (L1, L2, L3, N) have leakage to something not connected to the protection device (EGC or anything with continuity to it or true ground, other circuits is possible but probably not so common especially in this application) that exceeds the trip threshold.

Correct and you make good points not to be argumentative but the research I have seen shows that premisis wiring causes the most Electrical Shock Drowning (ESD) cases.
Either way reserch aside thats all you an EC are liable for and can reasonably be expected to prevent or am I missing something?
If a sewer system or oil pipe line leak onto your property causing a loss of use, injury or death then the liability is obvious, with a POCO and electricity its invisible but the liability for loss of use, injury or death is still there, its reasonable to expect a utility to not cause such an issue on their system, and its unreasonable for the NEC to try to address such a leak?
Perhaps a EC or local agency can help test for such unsafe conditions, or even a attorney specializing in that would be interested paying for testing if there were a 'class' of property owners affected by one particular utility's negligent practices.

When I do look at the research (IEEE) a notably higher proportion of accidents involving an electric current and a swimmer in a pond or lake happen in the United States and these mostly (not all) are related to 'premises' wiring.
Why the majority in US then? My theory is lack of Residual Current Device (RCD) feeder protection (or redundant RCD) vs a single point of failure GFCI protection.
The NFPA CMP concluded the same thing and changed the code to require a GFPE on a feeder to a dock, which is not as good as a RCD but its better than a standard breaker and wont nuisance trip like the inferior GFCI.

I'd bet a milkshake most US EC's never considered using a redundant GFPE breaker on a feeder to a area where people are wet like a dock, pool, water park, outdoor sauna, hot tub etc .. unless code required it.
GFPE is a such a easy way for the EC to add redundant protection and any property owner concerned with enhanced safety probably does not know to ask for one, instead they buy these 'green light' detectors.
A handyman or homeowner owner looking for a quick fix may remove or bypass a GFCI receptacle not knowing better, but they are less likely to replace a feeder main in the service.
I am not all about up-selling, but a GFPE on a outdoor feeder is a good upsell I think better than one of those 'green light' safe swimming gismo's.

 

[kwired]

Agreed

Correct and you make good points not to be argumentative but the research I have seen shows that premisis wiring causes the most Electrical Shock Drowning (ESD) cases.
Either way reserch aside thats all you an EC are liable for and can reasonably be expected to prevent or am I missing something?
If a sewer system or oil pipe line leak onto your property causing a loss of use, injury or death then the liability is obvious, with a POCO and electricity its invisible but the liability for loss of use, injury or death is still there, its reasonable to expect a utility to not cause such an issue on their system, and its unreasonable for the NEC to try to address such a leak?
Perhaps a EC or local agency can help test for such unsafe conditions, or even a attorney specializing in that would be interested paying for testing if there were a 'class' of property owners affected by one particular utility's negligent practices.

When I do look at the research (IEEE) a notably higher proportion of accidents involving an electric current and a swimmer in a pond or lake happen in the United States and these mostly (not all) are related to 'premises' wiring.
Why the majority in US then? My theory is lack of Residual Current Device (RCD) feeder protection (or redundant RCD) vs a single point of failure GFCI protection.
The NFPA CMP concluded the same thing and changed the code to require a GFPE on a feeder to a dock, which is not as good as a RCD but its better than a standard breaker and wont nuisance trip like the inferior GFCI.

I'd bet a milkshake most US EC's never considered using a redundant GFPE breaker on a feeder to a area where people are wet like a dock, pool, water park, outdoor sauna, hot tub etc .. unless code required it.
GFPE is a such a easy way for the EC to add redundant protection and any property owner concerned with enhanced safety probably does not know to ask for one, instead they buy these 'green light' detectors.
A handyman or homeowner owner looking for a quick fix may remove or bypass a GFCI receptacle not knowing better, but they are less likely to replace a feeder main in the service.
I am not all about up-selling, but a GFPE on a outdoor feeder is a good upsell I think better than one of those 'green light' safe swimming gismo's.

I have to disagree with you on there not being much risk from Neutral to earth voltage coming from the grounded service conductor. It may be true a majority of incidents are found to be from premises wiring problems but neutral to earth voltage exists pretty much everywhere an MGN distribution system is utilized. If your dock location is out at the end of a long line of just two wire distribution with one of them being the MGN, you can not balance the neutral on that section as the other phases aren't even there to try to achieve any balance.

This sort of thing has caused problems with livestock for years - stray currents because of NEV, it certainly will cause problems with humans submerged in water to achieve somewhat maximum conductivity level as well.

I've had service calls over the years for claims of shocking at tubs, showers, etc. that I could turn off the service disconnect and the voltage is still present and many are not even within cities/towns where there may be issues with stray voltage over the water piping between neighbors - it's coming from the utility MGN. I've measured voltage at almost any service enclosure to an isolated probe in the ground ever decided to check whether there was suspicion of a problem or just out of curiosity. Usually only a couple volts max but almost always is something measurable.

NEC requires equipotential bonding at art 680 applications. That eliminates touch potential even though the entire pool is sitting there at whatever the NEV voltage is at the service equipment. Outside of an ungrounded conductor being a problem at a pool most so called minor shock incidents are likely due to a hole in the equipotential bonding.

I had a woman that complained about weird tingling in her legs when she used her shower. Her husband never had any problems when he used it. It wasn't enough for her to definitely say it was electric shock, but she felt something and wanted me to check it out. I got nothing, but once we turned the shower on and drain started getting regular flow through it, we did start seeing same NEV from the water fixtures to the drain that we could measure at the service. Don't remember specifically what it was but was probably under 3 volts maybe even under 2. Low enough there usually is no complaints about anything. Water lines were at service neutral potential. Drain fitting in the tub was metallic but immediately connected to plastic drain piping. That drain piping eventually turned into old cast drain pipe before it left the building. My theory was earth potential was brought to the drain fitting once the piping had sufficient water flowing through it. My solution on that was to bond that drain fitting to the water piping at the shower valve. Problem went away. Imagine how much more of a problem this might have been if one were to fill the tub and submerge yourself in it so you have even more conductivity then touch the shower valve. That is more of the sort of situation you are in when at a dock and you bring even a couple volts of NEV out there.

 

[JB85]

I have to disagree with you on there not being much risk from Neutral to earth voltage coming from the grounded service conductor. It may be true a majority of incidents are found to be from premises wiring problems but neutral to earth voltage exists pretty much everywhere an MGN distribution system is utilized. If your dock location is out at the end of a long line of just two wire distribution with one of them being the MGN, you can not balance the neutral on that section as the other phases aren't even there to try to achieve any balance.

This sort of thing has caused problems with livestock for years - stray currents because of NEV, it certainly will cause problems with humans submerged in water to achieve somewhat maximum conductivity level as well.

I've had service calls over the years for claims of shocking at tubs, showers, etc. that I could turn off the service disconnect and the voltage is still present and many are not even within cities/towns where there may be issues with stray voltage over the water piping between neighbors - it's coming from the utility MGN. I've measured voltage at almost any service enclosure to an isolated probe in the ground ever decided to check whether there was suspicion of a problem or just out of curiosity. Usually only a couple volts max but almost always is something measurable.

NEC requires equipotential bonding at art 680 applications. That eliminates touch potential even though the entire pool is sitting there at whatever the NEV voltage is at the service equipment. Outside of an ungrounded conductor being a problem at a pool most so called minor shock incidents are likely due to a hole in the equipotential bonding.

I had a woman that complained about weird tingling in her legs when she used her shower. Her husband never had any problems when he used it. It wasn't enough for her to definitely say it was electric shock, but she felt something and wanted me to check it out. I got nothing, but once we turned the shower on and drain started getting regular flow through it, we did start seeing same NEV from the water fixtures to the drain that we could measure at the service. Don't remember specifically what it was but was probably under 3 volts maybe even under 2. Low enough there usually is no complaints about anything. Water lines were at service neutral potential. Drain fitting in the tub was metallic but immediately connected to plastic drain piping. That drain piping eventually turned into old cast drain pipe before it left the building. My theory was earth potential was brought to the drain fitting once the piping had sufficient water flowing through it. My solution on that was to bond that drain fitting to the water piping at the shower valve. Problem went away. Imagine how much more of a problem this might have been if one were to fill the tub and submerge yourself in it so you have even more conductivity then touch the shower valve. That is more of the sort of situation you are in when at a dock and you bring even a couple volts of NEV out there.

There nothing to balance on a single phase line. A two wire distribution, im assuming thats what you're talking about, one hot phase and 1 neutral, whatever is on the phase will also be on the neutral. The cattle on fence/ water line/ stray voltage issue you talk about is from the utility having that main neutral broke somewhere and that current is now finding another path to complete the circuit. And you are correct in the part of it being on that ground path bc of the neutral being bonded on the distribution system, but its bc of an OPEN neutral way more than it is soley bc they are bonded. The utility system neutral is by far a better path back to the source and when it is not broke current will always want to take that path

 

[tortuga]

I have to disagree with you on there not being much risk from Neutral to earth voltage coming from the grounded service conductor. It may be true a majority of incidents are found to be from premises wiring problems but neutral to earth voltage exists pretty much everywhere an MGN distribution system is utilized. If your dock location is out at the end of a long line of just two wire distribution with one of them being the MGN, you can not balance the neutral on that section as the other phases aren't even there to try to achieve any balance.

This sort of thing has caused problems with livestock for years - stray currents because of NEV,

OK Interesting, yeah I have definitely seen issues with it and livestock. The utilities here have dealt with it for years and due to lawsuits will fix it, I just dont think the NEC can fix that. Some even have in-house exprets on it and I am not one of them.
I do know they use a two bushing transformer fed Line-Line I have run conduit for the change.
There is a big horse facility out here and the POCO had them run two ducts for two concentric primaries, the pad mount transformer was L-L 12.5kv primary, instead of the more typical 7.2 kv L-N. They had to upgrade something like 2 miles of primary to do that.
They also did that at a house that has a swimming pool, two separate 2" pipes for primary run to a pad..
Another thing they can do around a body of water is if the load is low like summer cottages and lake homes they use the lower distribution primary 2.4kv, a old voltage they mostly no longer use, not sure if any of that makes a difference but they seem to think so, you @Hv&Lv and @JB85 here would probably know more than me on the utility side of things.

 

[kwired]

There nothing to balance on a single phase line. A two wire distribution, im assuming thats what you're talking about, one hot phase and 1 neutral, whatever is on the phase will also be on the neutral. The cattle on fence/ water line/ stray voltage issue you talk about is from the utility having that main neutral broke somewhere and that current is now finding another path to complete the circuit. And you are correct in the part of it being on that ground path bc of the neutral being bonded on the distribution system, but its bc of an OPEN neutral way more than it is soley bc they are bonded. The utility system neutral is by far a better path back to the source and when it is not broke current will always want to take that path

There is voltage drop across any conductor with current flowing through it. 1 or 2 volts is insignificant to operation of a 7200 volt circuit, but is still 1 or 2 volts. Drive a rod at every pole, you can never make a zero resistance connection to earth with any one of them. The more rods you drive the more overall stable of an earth reference you will have through the system, but is nearly impossible to have perfect zero resistance at any electrode plus you do have voltage drop across the grounded conductor if it is carrying current. We bond the grounded conductor of the secondaries supplying services to the grounded conductor of the primary system. Now you have whatever voltage rise is on the primary as well as whatever voltage drop is on the secondary contributing to what you will read for neutral to earth voltage at the service. The equipment grounding conductor connects to the grounded service conductor - that neutral to earth voltage gets extended to every piece of equipment that connects directly or indirectly to the EGC. You can put a ground rod at some piece of equipment, it will lessen the NEV, but only near the rod. Depending on resistance to earth at that rod the voltage may be more gradual of a drop off in some cases or rather quick drop off in others. 2 volts on a rod that has 10 ohm impedance should have 200 milliamps of current flowing through it. If you are standing there with shoes on and touch the EGC you feel nothing. If you are barefoot, some may feel something some may not. If you are immersed in water, you almost definitely will feel something. If the EGC (or electrode) is in the water it will have lower impedance than a ground rod in dirt, so you should be subject to even lower voltage. But the potential for problems is definitely there and if something malfunctions yet isn't a condition that will be easily noticeable to operation of electrical items, you have a more serious shock hazard out there but nothing indicating there is a problem. Doesn't matter how uncommon it may seem to be you will have no warning.

 

[Fred B]

That is what I been trying to emphasize with most my replies in this thread.

NEC needs to step up and come up with better solution then they have for these applications. Swimming pools and equipotential bonding required in those applications is good, but is impractical in large bodies of water. Some sort of method of isolating the system that supplies the dock would be better and still having ground fault protection on some level would enhance it even more. Ungrounded systems could maybe work, capacitance could maybe present problems though which is one advantage of still having grounded system, but need to find a way to isolate it from the regular premises grounding network. Easier said if dock is remote from rest of the regular premises but if you have building pretty much right close to the water it may get more complicated at assuring you keep things isolated.

All the comments that indicate NEV as issue is correct and that the pool bonding system does work in it's application to make the NEV a negligible issue but that as mention will not really work in a natural body of water and dock situation, thus why the NEC requirement for signage around a dock and out from the dock to say that swimming is prohibited and dangerous in the vicinity of the dock.

One unique issue that does arrive from swimming in and around a dock that has power is if there is voltage gradient around the dock as a person approaches they begin to feel the shock and the tendency is to swim toward the dock to get out of the water but that is likely the source and as they get closer the higher the voltage present and the more they get shocked. If this is high enough it will result in paralysis and shock drowning. This too is reason for not just signage but a readily accessible disconnect. But if the source is from another nearby dock or building your individual disconnect won't do anything thus the "NO SWIMMING" warning sign required in 555.

 

[kwired]

All the comments that indicate NEV as issue is correct and that the pool bonding system does work in it's application to make the NEV a negligible issue but that as mention will not really work in a natural body of water and dock situation, thus why the NEC requirement for signage around a dock and out from the dock to say that swimming is prohibited and dangerous in the vicinity of the dock.

One unique issue that does arrive from swimming in and around a dock that has power is if there is voltage gradient around the dock as a person approaches they begin to feel the shock and the tendency is to swim toward the dock to get out of the water but that is likely the source and as they get closer the higher the voltage present and the more they get shocked. If this is high enough it will result in paralysis and shock drowning. This too is reason for not just signage but a readily accessible disconnect. But if the source is from another nearby dock or building your individual disconnect won't do anything thus the "NO SWIMMING" warning sign required in 555.

Required signage is just a band aid, NEC needs to come up with more effective solution to eliminate the voltage potential, like requiring systems that are isolated from the utility supply or even maybe something like Ronk blockers? People have a tendency to ignore signs, even if you spell out the hazard in pretty simple to understand wording. There still is a risk if someone isn't intentionally in the water yet falls in for whatever reason as well.

 

[don_resqcapt19]

All the comments that indicate NEV as issue is correct and that the pool bonding system does work in it's application to make the NEV a negligible issue but that as mention will not really work in a natural body of water and dock situation, thus why the NEC requirement for signage around a dock and out from the dock to say that swimming is prohibited and dangerous in the vicinity of the dock.

One unique issue that does arrive from swimming in and around a dock that has power is if there is voltage gradient around the dock as a person approaches they begin to feel the shock and the tendency is to swim toward the dock to get out of the water but that is likely the source and as they get closer the higher the voltage present and the more they get shocked. If this is high enough it will result in paralysis and shock drowning. This too is reason for not just signage but a readily accessible disconnect. But if the source is from another nearby dock or building your individual disconnect won't do anything thus the "NO SWIMMING" warning sign required in 555.

Unfortunately the sign language required in 555.10 is a plaintiff's attorney dream.

“WARNING — POTENTIAL SHOCK HAZARD — ELECTRICAL CURRENTS MAY BE PRESENT IN THE WATER.”{/quote]
It acknowledges that the owner knows of the hazard but does not tell the reader how to avoid the hazard. Slam dunk verdict in favor of the plaintiff, because of faulty sign language. This type of sign must not only tell the reader what the hazard is, but also tell the reader how to avoid the hazard.

I have submitted PIs a couple of times to fix this citing both court cases and the ANSI rules for warning signs, but they have been rejected.

If you are the owner of a facility that requires this sign, you need to add something along the lines of "keep out of the water" or "do not enter the water".

 

[kwired]

Unfortunately the sign language required in 555.10 is a plaintiff's attorney dream.

Can also come down to who is responsible for maintaining the sign after initial install along with installer being able to prove they did provide proper sign at install should it been missing or in poor condition after some incident.

 

[JB85]

OK Interesting, yeah I have definitely seen issues with it and livestock. The utilities here have dealt with it for years and due to lawsuits will fix it, I just dont think the NEC can fix that. Some even have in-house exprets on it and I am not one of them.
I do know they use a two bushing transformer fed Line-Line I have run conduit for the change.
There is a big horse facility out here and the POCO had them run two ducts for two concentric primaries, the pad mount transformer was L-L 12.5kv primary, instead of the more typical 7.2 kv L-N. They had to upgrade something like 2 miles of primary to do that.
They also did that at a house that has a swimming pool, two separate 2" pipes for primary run to a pad..
Another thing they can do around a body of water is if the load is low like summer cottages and lake homes they use the lower distribution primary 2.4kv, a old voltage they mostly no longer use, not sure if any of that makes a difference but they seem to think so, you @Hv&Lv and @JB85 here would probably know more than me on the utility side of things.

We got rid of all the 4kv stuff where I work. Lower voltage = higher amperage, the fault current is much higher on 4kv and is more dangerous to work in and to the public should a line go down

 

[tortuga]

We got rid of all the 4kv stuff where I work. Lower voltage = higher amperage, the fault current is much higher on 4kv and is more dangerous to work in and to the public should a line go down

That is my understanding also but also I am told its a trade off,
A higher voltage (7.2kV) you get a neutral - earth voltage rise and further away from the system. With a 3X lower primary voltage around a lake like 2.4kv the N-E voltage rise will be something like 9X lower.