Stray Voltage

[cppond]

This issue came up on another thread. I don't know that it occured in the thread where this came up, but it is good for people to know about. I am no expert, but I will tell you what I know.

There does not have to be electricity in the pond for this to occur as water is a great conducter and even wet concrete can theoretically carry the stray voltage. "Stray voltage" is a voltage which develops on the grounded neutral of either the pond wiring or even the utility distribution system. The most common cause of stray voltage is high resistance on the neutral wire caused by loose or corroded connections or undersized wires. Some times the wrong type of electrical equipment is used during installation, some times it's corrosive switches and connectors, or frayed insulation, faulty equipment, poorly grounded systems, overloaded power lines and being at the end of an electrical service line.

It can be a bunch of different things and the severity of the problem can vary depending on how much equipment is being run at any given time.

A couple of weekends ago a neighbor of mine discovered a similar problem around his swimming pool. In one area of concrete when it gets wet you get a little tingling. When the area that got wet dripped water into the pool, the voltage could theoretically carry into the pool for a moment. The "shock" was not sufficient to hurt people, but stray voltage has been known to kill fish and apparently has been an ongoing issue in cow milking facilities.

That's all I know. I am not saying it happened in any particular instance, but it's something of which we should all be aware.

[Russell Peters]

Quote: Originally Posted by cppond This issue came up on another thread. I don't know that it occured in the thread where this came up, but it is good for people to know about. I am no expert, but I will tell you what I know. There does not have to be electricity in the pond for this to occur as water is a great conducter and even wet concrete can theoretically carry the stray voltage. "Stray voltage" is a voltage which develops on the grounded neutral of either the pond wiring or even the utility distribution system. The most common cause of stray voltage is high resistance on the neutral wire caused by loose or corroded connections or undersized wires. Some times the wrong type of electrical equipment is used during installation, some times it's corrosive switches and connectors, or frayed insulation, faulty equipment, poorly grounded systems, overloaded power lines and being at the end of an electrical service line. It can be a bunch of different things and the severity of the problem can vary depending on how much equipment is being run at any given time. A couple of weekends ago a neighbor of mine discovered a similar problem around his swimming pool. In one area of concrete when it gets wet you get a little tingling. When the area that got wet dripped water into the pool, the voltage could theoretically carry into the pool for a moment. The "shock" was not sufficient to hurt people, but stray voltage has been known to kill fish and apparently has been an ongoing issue in cow milking facilities. That's all I know. I am not saying it happened in any particular instance, but it's something of which we should all be aware.

Carl, you bring up some very good points. If a pond is not properly bonded then it is a possibility that stray electrical current can find its way into your water. If you have a gunnite pond you need to attach a #8 copper wire to the rebar with a brass connector. This same wire needs to be connected to your pumps. This creates the equivalent effect of bonding to a ground rod.

[cppond]

Quote: Originally Posted by Russell Peters Carl, you bring up some very good poitns. If a pond is not properly bonded then it is a possibility that stray electrical current can find its way into your water. If you have a gunnite pond you need to attach a #8 copper wire to the rebar with a brass connector. This same wire needs to be connected to your pumps. This creates the equivalent effect of bonding to a ground rod.

Thanks, Russell.

I am sure that you know a lot more about it than I do.

[cppond]

More info:

"Stray voltage" is a term commonly used throughout the electric utility industry to describe when infrastructure devices, such as lamp posts, manholes, gratings and junction boxes become unintentionally charged with electricity. The cause of this unintended electric leakage is due to a variety of conditions including cracked insulation, frost heaving, expansion and contraction of wiring, physical damage to the lines and so on. In major metropolitan areas, such as New York City, "stray voltage issues" have become a major concern. In 2005, Jody Lane, was killed in New York City after she was electrocuted after stepping on a manhole cover.

Stray voltage - Wikipedia, the free encyclopedia

This past weekend a bunch of people sitting along the edge of the pool were complaining about getting “shocked”, so I tripped the breakers for the pump and pool shed outlets and pool lights, but the problem didn’t go away. I noticed if you touched the pool water and were touching the dry cement pavers around the pool you wouldn’t get shocked, but once you added water, zap. So, being a maintenance mechanic and knowing a very little about electricity 101, I pulled out my meter and started checking for stray voltage. I check everything from the panel in the house to the pool and found nothing, from the pool water to both the ladder and entry handrail, nothing. From pool water to the dry pavers around the pool, nothing, from the pool water to the wet pavers, bingo between 2.9 and 3.4 volts. What should I do next, any suggestions would be appreciated.

Mike Holt Newsletter




She put her hand in the hot tub.... nothing. I then asked her to take her shoes off and stick her hand in. She did and she was "jolted" by the shock. My fears were confirmed, a major electrical problem with the hot tub. We immediately called our electrician who came out in the morning. He tested with his fluke meter and was getting 8 volts of electricity from the hot tub. He than disconnected the meter pan and shut down all power to the house. He went back to test again and was still getting readings of 8 volts from the hot tub, the sprinkler system, and the water meter.

Stray Voltage - No You are not Crazy

[Nancy M.]

Quote: Originally Posted by Russell Peters Carl, you bring up some very good poitns. If a pond is not properly bonded then it is a possibility that stray electrical current can find its way into your water. If you have a gunnite pond you need to attach a #8 copper wire to the rebar with a brass connector. This same wire needs to be connected to your pumps. This creates the equivalent effect of bonding to a ground rod.

EXACTLY.... I believe that at least here in California, that is a city code.

[Bob Winkler]

we have to bond the pumps and everything here in Colorado too. Not as pretty, but it works...

[Rich L]

Heavy power lines overhead and normal power lines carrying current and running along with other leads for a distance can have voltages induced.

An electrician working on aircraft elevators had a problem with the elevators operating improperly. He found a sencing wire with 20 volts on it. He was really confused when he laid a cable along the ground and it also showed a significant voltage without being connected to anything.

I had him ground both ends of the sencing lead and the voltage disappeared. The lead was in the cable way of some heavy power runs and the voltage fluctuated with the current in the power runs. Grounding the sheath caused the voltages to go to ground and not impact the sencing leads.

The pond won't be protected if the gunnite is coated with an insulating barrier such as fiberglass, polyurea or any directly applied coating that provides an insulation coating between the gunnite and the water. Grounding the rebar is proper but most cement and gunnite in-ground ponds are well grounded by the extensive contact between the pond material and the earth.

There are two conditions in our ponds. One is in a pond where the water is isolated from earth(ungrounded) where the pond has an insulation coating between the water and ground potential The other is grounded where the pond water is well grounded by using metal components or other products that will conduct electricity. Isolated water won't conduct to ground and touhing a hot lead and the water won't produce a shock. However it will be at ground level if a fixture leaks so the water reaches a component that's grounded. This could be a light fixture of an electrical heater up in the filter room or even the makeup water when the ponds filling and the metalic line of the makeup plumbing is close enough to the pond water for the water to conduct into the filter water. If insulating layers of pond coatings delaminate, the pond is likely grounded.

All this depende on the amount of salts(TDS) in the water. Folks with snow runnoff won't have the same problem as those who use well water.

The best solution is to positively ground the pond water. Pond water won't cunduct current well so a ground in a remote filter room won't provide the same protection in the pond as a good conducter close to potential voltage sources. The ground must be good enough that a gfci will trip when a ground fault is created by current into the pond strong enough to cause harm to people.

[Russell Peters]

Quote: Originally Posted by Nancy M. EXACTLY.... I believe that at least here in California, that is a city code.

It is a National Building (Electrical) Code. Most cities have to adopt the National Building Code and then adopt their own Local Building Codes.

[cppond]

Quote: Originally Posted by Rich L Heavy power lines overhead and normal power lines carrying current and running along with other leads for a distance can have voltages induced. An electrician working on aircraft elevators had a problem with the elevators operating improperly. He found a sencing wire with 20 volts on it. He was really confused when he laid a cable along the ground and it also showed a significant voltage without being connected to anything. I had him ground both ends of the sencing lead and the voltage disappeared. The lead was in the cable way of some heavy power runs and the voltage fluctuated with the current in the power runs. Grounding the sheath caused the voltages to go to ground and not impact the sencing leads. The pond won't be protected if the gunnite is coated with an insulating barrier such as fiberglass, polyurea or any directly applied coating that provides an insulation coating between the gunnite and the water. Grounding the rebar is proper but most cement and gunnite in-ground ponds are well grounded by the extensive contact between the pond material and the earth. There are two conditions in our ponds. One is in a pond where the water is isolated from earth(ungrounded) where the pond has an insulation coating between the water and ground potential The other is grounded where the pond water is well grounded by using metal components or other products that will conduct electricity. Isolated water won't conduct to ground and touhing a hot lead and the water won't produce a shock. However it will be at ground level if a fixture leaks so the water reaches a component that's grounded. This could be a light fixture of an electrical heater up in the filter room or even the makeup water when the ponds filling and the metalic line of the makeup plumbing is close enough to the pond water for the water to conduct into the filter water. If insulating layers of pond coatings delaminate, the pond is likely grounded. All this depende on the amount of salts(TDS) in the water. Folks with snow runnoff won't have the same problem as those who use well water. The best solution is to positively ground the pond water. Pond water won't cunduct current well so a ground in a remote filter room won't provide the same protection in the pond as a good conducter close to potential voltage sources. The ground must be good enough that a gfci will trip when a ground fault is created by current into the pond strong enough to cause harm to people.

Thank you, Rich.

Can you explain the difference between grounding and bonding and how to properly achieve each in a liner pond and in a concrete pond? I am trying to get a better understanding of this. The grounding part seems simple enough in theory, but the bonding seems to involve a little more.

[Rich L]

They both amount to the same thing. A bonded component (pump, heater, etc. is tied directly to ground. Bonds are used to insure the component is grounded even though you will also have a grounded system. Most pumps come with a 3 - prong ground plug. If purchased without the plug, a similar one or a hard wire must be carried to the system ground circuit.

The problem here is lots of people cut the ground lug to accommodate older wiring or use a 'temporary' two wire extension cord. Both are illegal and the owner can be held liable for an accident when the code is ignored. Poor grounding can develop with age but that normally happens in poor installations. You should check GFCI breakers monthly and you can also buy a test plug that can trip a Master gfci from a remote location at most hardware stores. They check for proper wiring and have a button that will trip the master from a remote receptacle.

If you’re standing on wet ground and you feel an electric shock when you touch the water you’re pond isn’t effectively grounded.

Masonry ponds without an insulating coating are grounded where the rebar is continuous so the entire masonry surface is bonded.

Bonding an insulated pond is another matter. Pure water isn’t a good conductor, it becomes a conductor as the TDS is raised, so a ground at one point won’t be an effective ground at a point at the other end of the pond (or in the filter area) unless the TDS is higher than we want it to be. One limited advantage is the poor conductivity isn’t likely to carry enough current to be dangerus but would you like to test it with one of your kids? It doesn’t become a problem until we insulate the masonry surface when we coat it with an insulator.

I don’t happen to know the code in a case like that but I would think we would have to bond it in several places if the conductivity is too low. GFCI breakers trip at less than 0.030 (30 milliamperes)amperes and current becomes normally becomes lethal at a little over 0.100 ma so I would expect the GFCI to protect us. It becomes a problem at lower currents that won’t kill you directly but can cause you to have an accident or even lock your muscles so you cannot swim.

Fortunately we worry about our koi enough to want too do something about it but pond safety protects us too.