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Measuring Current on Water Pipes

Plumbing Current Magnetic Fields
EMF from Water Pipes


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The most common source of elevated magnetic field readings 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 (more info)


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 selection of an electrician. If you wish to proceed, make an online payment at the link below, and we will email a checklist to guide the electrician in performing the testing in a structured way. We will then talk with the electrician, evaluate the readings, and advise on how to proceed. This often includes sending information to help a plumbing contractor understand the work that is required. This price applies only to single family residences or duplexes. Commercial or multi-occupancy buildings will incur higher costs.

  On-Line Payments:

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 is required.


Related 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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