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Measuring AC Current on Water Pipes

Plumbing Current Magnetic Fields
EMF from Water Pipes

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The Water Pipe EMF Problem

The most common source of elevated magnetic field readings (high EMF) in homes is electrical current on a water pipe. This is more accurately described as neutral current diversion into a metallic plumbing and grounding system, also referred to as plumbing current, or ground current. Small commercial buildings can also exhibit this condition. The situation exists when some of the current that would normally return through the electrical service line feeding the building is instead channeled into the grounding system, where it returns to the transformer by way of alternate paths, including water pipes, the public water main, and neighboring residences. This unbalanced current creates a strong magnetic field with a wide spatial extent. The type of power distribution system used in the U.S., in combination with important National Electrical Code grounding requirements, establish the underlying conditions for this problem to occur. It is more common in communities with moderate to high housing density, especially those served by overhead power distribution lines, but it can occur anywhere.

Plumbing Current
Drawing by Ed Leeper from Silencing the Fields

Plumbing Current Remediation

This undesired current flow can be blocked very effectively, and in a manner that is code compliant, by the installation of a dielectric coupler, or insulating coupling, in the water supply line to the building. Several strong cautions are necessary before this work is planned. In some extreme cases, the problem results from a partial failure of the power feed to the building (open neutral), and can represent a potentially serious electrical shock and fire hazard. If intervention is undertaken without an analysis of the nature of the problem, and if the integrity of existing electrical facilities is not verified, extremely hazardous conditions can be created. In addition, a large sum of money will have been spent on an ineffective solution.

We routinely resolve plumbing current problems, and can coordinate the activities of local service providers at any location through telephone consultation. There is a flat-rate fee of $150 for this service. A brief conversation is provided at no cost to determine the nature of your problem, and to advise on the next steps. If you are ready to proceed, make an online payment at the link below, and contact us to coordinate the electrician's schedule with our availability. You should then download the Electrical Testing Outline, which will help the electrician understand how the testing will be performed.

We will guide the electrician through the procedure over the phone, evaluate the readings, and advise on how to proceed. This usually includes sending information to help a plumbing contractor understand the work that is required. The stated price applies only to single family residences or duplexes. Commercial or multi-occupancy buildings will incur higher costs.

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Electrical Testing Outline (PDF)

Selection of an Electrician

Our advice for finding an electrician to work with us over the phone is to start by asking friends if they have used one with good results. Also, check referral and review sites and avoid anyone who has demonstrated questionable business ethics. From there, narrow your search to the small companies, like a one to three person shop. The personal attention to your problem and the level of craftsmanship are usually much higher. Avoid the large companies with the largest ads, who are likely to just send out the next truck in rotation, and you never know what you will get. Perhaps most important is to select a person who is open to working with you on something a little outside the typical electrical job. They don't need to know anything about EMF problems or electrical current on water pipes. In fact, it is usually best if they don't claim to know these things because they are easier to work with. A good attitude, an open mind, and the ability to work cooperatively with another person is priceless. Prioritize those qualities in your selection process.

The one thing they must have is a good clamp-on ammeter, or amp clamp. Any qualified electrician should have one, and it should have a digital readout with at least 1 decimal place. (We recommend the Klein CL220 because it is widely available at reasonable cost.)

Here is what to tell the electrician that you need to have done:

  1. Measure current on the incoming service conductors in the panel.

  2. Measure current on the incoming water line.

  3. Measure current on grounding conductors inside the house.

Additional Technical Explanation

Misinformation abounds on the causes and correction of plumbing current problems. Some sources advise driving additional ground rods (does nothing). Others even tell you to disconnect required grounds from the water pipe in the building (dangerous!). Still others say it cannot be fixed, and suggest that you give up on the problem. This is not a mysterious issue. It is understandable, explainable, quantifiable, and in almost all cases, fully correctable. For those who wish a further explanation, the following should be helpful:

  • Type I plumbing current is described above. It results from current utilization within the building where the analysis takes place. The magnitude of the problem tracks the changing power load as electrical devices switch on and off. When power to the building is turned off, it goes away. Correctable as described above.

  • Type II plumbing current is also described above. It results from current utilization in another building besides the one under analysis. Power to the building under analysis can be turned off, and the utility meter can even be removed, but the current still flows and the magnetic field is still present. The current magnitude can be seen to vary as electrical devices in another building switch on and off. This problem can occur because of a defective neutral in the service drop to the other building, but this is not always the case. Type I and Type II often exist together in the same building, and can add or subtract. Correctable as described above.

  • Type III plumbing current exists when primary neutral return current flows over the secondary portion of the neutral system into the building and crosses over into the plumbing system, usually because of a deficiency in the utility distribution system. This is less common and of lower magnitude than Types I and II. It is usually correctable as described above, but if current is flowing into the earth rather than into the water main, a different approach may be required.

  • An open neutral in the electrical service line to the building will often result in very high, and highly variable, current on the water service line. This is universally recognized as a serious safety problem among electric utilities and electricians. It is very important to note that the absence of any current measured on a water line does not confirm that an open neutral condition DOES NOT exist. There may simply be no loads operating in the building. Also, a measurement of many amps of current on the water line does not indicate that an open neutral condition DOES exist. Only structured testing under controlled load conditions will permit this determination. A major implication of this is that a plumbing contractor cannot use a simple current measurement as a singular indication that it is safe to cut into a pipe. A voltage of 120 Volts or more could appear across the two ends of a cut pipe without warning. With wet hands on a copper pipe, this could be a fatal mistake.

  • Beast of Burden Testing - When the local electric company is called out to investigate a customer complaint of high magnetic fields from a water line, they will often bring a load testing device commonly called the "Beast of Burden." This will load each side of the incoming electric service in turn, as the tech measures voltages (called a neutral voltage shift). The fallacy of this test is that as long as the house has an intact metallic water line, they will conclude that everything is OK even if there is a completely open neutral connection in the service to the house! Unless they use an amp clamp on the neutral conductor and on the water pipe, this test is meaningless. It is shocking how poorly this simple problem is understood by the people who are responsible for delivering electric power to our homes and businesses.

Related Ground Current Issue

Earth Current refers to the flow of primary return current through the earth back to the serving substation. It is not the type of current discussed on this page, but it is accurately referred to as ground current. Primary neutral return current enters the earth at any point where the electrical system neutral is connected to a grounding electrode. This condition is a consequence of the multi-grounded-neutral (MGN) system that is universally used for power distribution in the US. This system evolved early in the history of electrical power use because it offered a number of safety advantages. A fundamental precept of the system is that the earth (which is conductive) functions as a current return pathway to supplement the neutral system, and to handle transitory overvoltages due to lightning or high voltage faults. This is a major route by which primary current returns to the substation. The utility goes to great length to build and maintain a low resistance ground grid at the substation to handle the current. There may be adverse consequences from earth current flow, such as the establishment of earth surface voltage gradients. This is especially true for the dairy farming industry, where it is one component of the stray voltage issue. It also becomes significant in the design of residential environments for electrically sensitive individuals.


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