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Alternating Magnetic Fields

Any path of Current will produce a Magnetic Field in free space. If the current is relatively constant, we define it as DC (Direct Current). If the current is changing with time, we define it as AC (Alternating Current). Allowing a limited amount (by a fuse, circuit breaker, and the load resistance) of charge / current flow will allow the supply voltage to remain fairly constant, and yet provide useful output, or work.

During passage of current, a magnetic field is formed around the current path, resembling a series of concentric sleeves, with the strongest field nearest the current path, as shown below looking at a cross-section of the wire.

field form, looking at the end of a wire

The field will have directional properties that depend on the direction of current flow, with the convention being a clockwise, or anti-clockwise direction, depending on direction of current flow (rather than trying to be exacting and show the actual direction, simplified curved lines will be used for ease of illustration). There is a planetary magnetic field that we are all exposed to indoors and out, as most structures are transparent to magnetic fields. While this is necessary for life, and good health, as we know it, of greater interest for our purposes are the artifical ones produced by us and found indoors or out where we work / live / play. While it may be comforting to think that these fields remain constrained within the insulation surrounding the wire, unfortunately they do not. That is the reason why these fields impact biological systems, and the pressing question becomes not "if", but "how much" and "for how long." Nontheless, proper wiring practices cause the supply and return wiring and their respective currents to be within the same cable, the respective magnetic fields overlap, and being identical and of opposite polarity, cancel. Under such conditions the magnetic field will not be measurable more than a few inches from the cable.

The magnetic fields of present interest are those that are alternating. They can be produced from power distribution wiring, grounding interconnections to mask a fire hazard, wiring errors, and locally from appliances. While those from appliances are point sources, whose level of emission drops off dramatically with increasing distance from the source, they are nonetheless important if exposure is lengthy (as from a stove-top exhaust fan).

Powerline Magnetic field
Electric Fire Hazard

The fire hazard implied above occurs because neutral connections exposed to weather (or simply due to passage of time and oxydation (rust)) fail, causing unstable and dangerous voltages (170 in the sketch above). Grounding interconnections to multiple metallic systems provide backups to the main neutral wire, and stabilize voltages. But multiple neutral connections between multiple systems causes stray current flow everywhere, as below. Unfortunately, as if placing salt on the wound, interconnected systems sharing current may also involve cable TV, telephone, metallic waste piping, and even gas piping. Cutting into any of these systems then, without considering a connection with the electric system, can be a deadly mistake (more details at Stray Currents and Voltages). The desire to improve your system can bring on moral issues, however. Using the sketch below, if the users start isolating themselves from redundant systems (and it can be done legitimately and safely), and the one shown with the broken neutral experiences a house fire as a result, whose fault is it? This is further complicated by the fact that the uninformed, may not wish to become informed, possibly saving their home . . .

Neighborhood Shared Neutral Currents
Real-life Neighborhood fields

Fields from wiring errors are more insidious because they only occur when the mis-wired circuit(s) is(are) in use. What happens is that the current going from the breaker panel to the using device sees multiple paths to return through. In doing so the current splits, reducing cancellation effects from nearby opposing currents, and generating fields that may engulf the structure. These may have an instantaneous on / off character, partly based on user patterns (such as turning lights on / off) or automated devices (such as refrigerators, furnaces, etc.).

Mis-wired circuit
Ion Resonance due to the Earth's Magnetic field

Most residential structures are transparent to magnetic fields. The interaction, however, is more complex than from electric fields, causing unusual "windowing" effects. That is, effects manifest most easily at certain intensities and/or frequencies. Although a generally accepted (short-term) exposure limit is 719 A/m (Amps per meter) or 9040 mG (milliGauss), even for the single-frequency exposure to power line frequencies (60 or 50 cycles/second) some of the marked effects of long-term exposure are increases in various diseases above 2mG, and doubling of leukemia above 4 mG, among others. The sketch above, adapted from "Cross Currents," By Robert O. Becker, and the contribution by Professor Liboff to the Bioinitiative 2012 (Section 17, Electromagnetic Medicine: Non-Inductive, Non-Thermal Modalities, on page 1110), shed some light on the "windowing" mechanism>.

I am acquainted with a client who was having trouble sleeping. The client lived in a detached home without the interconnections typical of metallic public water systems. However, the client's bedroom was on the second floor where the bed was closest to an exterior wall adjacent to the road, with the client sleeping with the head closest to the wall. While the client did not have a power line directly next to the home, there was a telephone wire trunk at the approximate height of the bed. This telephone trunk served as a redundant neutral interconnection between electric users, and thus emitted a magnetic field whose reach was most prominent near the exterior wall. Neutral interconnection currents and their resultant magnetic fields are erratic, demonstrating steep transient haracteristics that perhaps belong more appropriately in the harmonics section. Two simple no-cost solutions were to sleep with the head on the other end of the bed, or away from the wall close to the road. A greater improvement would have been available by sleeping in another room further away from the road.

Some Indoor Solutions, in order of increasing cost:
1) remove all line-powered devices from the bedside,
2) identify miswired circuits and have them corrected,
3) sleep furthest away from redundant neutrals,
4) disconnect from redundant neutrals, if you understand the shifted risk,

Some Outdoor Solutions:
1) use a counter field to produce an area of magnetic cancellation (www.emfservices.com).