Have You Heard of Magnetic Fields?

A magnetic field is the type of EMF that can have the highest potential for causing adverse biological effects.

Our electric power travels to our home and appliances as alternating waves of current (AC). It travels at an extremely low frequency (ELF) of 60 cycles per second (60 Hz in North America). At this low frequency, electric fields and magnetic fields exist as separate forces with unique properties. They are often collectively (and inaccurately) referred to as electromagnetic fields.


So, what’s the difference between an electric field and a magnetic field?

An electric field is present wherever electricity is present, even though no current is flowing (no electricity is in use). Its strength is proportional to the voltage of the electrical supply and is measured in volts per meter. An electric field is blocked or substantially reduced by intervening structures, including trees and most common building materials.

A magnetic field, however, is present only when electric current is flowing (electricity is in use). Its strength is proportional to the amount of the current. It is measured in milli-gauss (mG) in the United States.

A huge issue here is that unlike electric fields, magnetic fields are not substantially reduced by most materials.


Can high levels of a magnetic field impact my health?

Peer reviewed studies have shown that elevated AC magnetic fields have been associated with:

  • Depressed levels of the neuro-hormones, serotonin, and dopamine
  • Behavior changes
  • Elevated serum triglyceride levels
  • Altered circadian rhythm.
  • Release of noradrenaline within 15 minutes
  • Exposure during gestation contributes to learning difficulties.
  • Prolonged exposure can result in
    • single and double DNA strand breaks
    • leukemia
    • lymphoma
    • brain cancer
  • Dogs are six times more likely to develop lymphoma.


What are the Building Biology recommendations for safe levels of magnetic fields?

Building Biology Evaluation Guidelines

No Slight Moderate


Concern Concern Concern


AC Magnetic Flux Density in MilliGauss (mG)

< 0.2 0.2 – 1.0 1.0 – 5   > 5
AC Magnetic Flux Density in NanoTeslas (nT) < 20 20 – 100 100 – 500

    > 500


What type of sources inside or near my home create magnetic fields?

A magnetic field is always produced when current is flowing through a wire. It is the source of the magnetic field can determine how detrimental it could be to our health. Here are three sources that can create magnetic fields in our environment. In the order listed, each is more insidious with respect to their ability to injure us:

  • Point Sources: Appliances, transformers or electric motors, etc.
  • Overhead Power Lines (for example): or wherever a hot wire delivering the electric current and its associated neutral wire are not right next to each other.
  • Wiring errors in our home:
    • Two neutral wires on separate circuits connected together intentionally or otherwise
    • A neutral wire is connected to a ground wire (other than at main circuit breaker panel)
    • A neutral wire is accidentally or intentionally connected to a metal plumbing pipe
    • There is an incorrectly wired 3-way switch


What do you mean by hot, neutral and ground wires?

The electricity coming to our home and distributed throughout our home always travels to us on a hot wire. This is the wire that has the voltage on it. Once it reaches it’s destination (your table lamp, electric stove, fridge, etc.), the same amount of electricity that traveled to it on that hot wire must return to its source over a neutral wire. In many cases there is a ground wire for safety reasons that, if all is working properly, should not have much electricity on it (no voltage and no current).


Why is a wiring error or overhead power lines (for example) of more concern than a point source?

The answer to that requires you to understand a basic physics principle called the “right hand rule for magnetic fields”. This states that the magnetic field made by a current in a wire, curls around the wire in a ring (like ripples when you drop a pebble into in a pond) in a specific direction. You can find the direction by pointing your right thumb in the direction of the current in the wire and curling your fingers. Your fingers will be curled in the same direction as the magnetic field around the wire.

                      That is why you need not be concerned as much with magnetic fields from the power cord to your table lamp. As you have seen, power cords have two (or three) wires. A hot wire, a neutral wire (and sometimes a ground wire). And, the wires are very close to each other. The magnetic field created by the hot wire, and one created by the neutral wire, are in opposite directions and with equal current, and so the magnetic fields are almost entirely canceled. A ground wire, if any, will not produce a magnetic field as there should be no electricity passing through it.

In fact, the light bulb in your table lamp is a point source. The magnetic field emanating from a point source will dissipate by 1/r3 (one over the cube of the distance…very rapidly!


What is the problem with overhead power lines?

You can see in the following photo that the wires that are strung between electrical distribution poles (or transmission towers) are separated by a significant distance. As a result, the magnetic fields created by the hot wires (there are usually 2 or 3 hot wires) and the neutral wire are not canceled as much. In fact, they can augment each other to create higher field levels. Additionally, distribution lines are usually operating with some degree of net imbalance, which causes the magnetic field to drop off more slowly with distance (see the following section which discusses wiring errors and net currents).


What happens when we live too close to overhead power lines?

Within neighborhoods supplied by electricity using overhead distribution lines, people in houses that are close to these lines are at risk of being subject to higher levels of magnetic fields. These fields dissipate by1/r2 (one over the square of the distance…significantly less rapidly than point sources. Also, these lines carry many times the voltage and current that is in your home so the fields are much stronger to begin with! And remember, metal siding or other material that can block other types of electromagnetic radiation, will not block these magnetic fields! Also note in the picture below the transformers on the poles that convert the 7,000 volts to 120 volts going into your home. As mentioned earlier, these are point sources and as such generally do not bring very high levels of magnetic fields into your home.


How far do I have to be from a power line to avoid a high magnetic field?

The strength of the magnetic field from power lines depends upon the type of line and how much current is moving through it at the time. Given the number of variables, a definitive answer could not be provided that applies under all conditions.  The following graph can give you an idea of distances that you need to be from a type of power line to be at a safe level (let’s say 1 mG or less). I recommend having field measurements done to determine the influence of any power line closer than 500 feet from your home.

Are there other situations where separation of hot and neutral wires can be an issue?

Houses built in the 1940s and earlier used a type of wiring called knob and tube. This type of wiring creates huge magnetic fields that affect the entire house because the hot and neutral wires were separated (see photo below).

When electricity is brought to houses in a neighborhood underground there is not as much an issue as the power lines all come in through the same conduit. Thus, there is not much separation between hot and neutral wires.


What is the problem with wiring errors?

Once electricity travels from its source on a hot wire to its intended destination; an appliance, lamp, etc., it must return in its entirety to that same source. However, electricity does not always take the most obvious path. It takes every path it can. It will follow the hot wire to the appliance, lamp, etc., and then do whatever it does to return to its source. Sometimes it will return to its source but not the way that was intended. As such, it is possible for wiring to be incorrectly installed, either intentionally, unintentionally, or compromised for other reasons, such that everything will seem to work correctly but with the additional outcome of large magnetic fields that go unnoticed. This is what we are referring to as wiring errors.


What is a net current?

If the electricity takes multiple return paths where not all of the initial current is returning on the correct neutral wire, an imbalance is created as the magnetic field created by the outgoing hot wire is not fully balanced by the return neutral wire. This imbalance is referred to as a “net current”. Electricians should understand the term “net current”. “Net currents” are not a good thing! The National Electrical Code (NEC) includes requirements to prevent them. They cause huge magnetic fields! The magnetic fields dissipate very slowly (one over the distance or 1/r). Most electricians either do not know about magnetic fields or choose to ignore them. They certainly do not have instruments to measure them. That is why when talking to an electrician about wiring errors, we do not talk about magnetic fields but rather “net currents”.


As mentioned earlier, these imbalances happen in a home when:

  • Two neutral wires on separate circuits are connected together intentionally or otherwise
  • A neutral wire is connected to a ground wire (other than at main circuit breaker panel)
  • A neutral wire is accidentally or intentionally connected to a metal plumbing pipe
  • There is an incorrectly wired 3-way switch

If high magnetic fields are found throughout a home but dissipate very slowly such that they travel across a room or multiple rooms, it could be caused by wiring errors. They are not that easy to find. They often must be traced and that sometimes means opening up a circuit breaker panel. That requires an electrician (Building Biologists are generally not also electricians but we have been trained to work with them on matters such as this). It can be a time consuming and tedious process.


Are wiring errors common?

Unfortunately, it is estimated that 60% to 80% of homes in the US have some kind of wiring errors. These are not only caused by untrained do-it-yourself people who unknowingly take shortcuts, but sometimes by trained and certified electricians. And home inspectors can often miss them or even ignore them. They are mostly concerned that a house does not burn down when hit by lightning and that occupants do not get electrocuted by faulty wiring. They are almost never concerned with magnetic fields.


So, how do I protect myself from elevated levels of magnetic fields?

The order of advice for protecting ourselves from elevated levels of electromagnetic radiation is:

  • Eliminate the source of the radiation
  • Increase our distance from the source of the radiation
  • Shield ourselves from the source of the radiation or (in the case of dirty electricity) filter It out.

Although the first two recommendations make sense for all four types of man-made electromagnetic radiation, shielding does not work well for AC magnetic fields. There are some soft metals such as Mu-Iron or G-Iron that can absorb some of the AC magnetic field radiation produced by the flow of electric current, however they are very expensive and hard to work with. I have heard some estimates that the best results using this approach does not fully result in the desired reduction.


If wiring errors are suspected:

If wiring errors are discovered, it is very important to fix them for another reason. Though dirty electricity can be filtered out using either plug-in filters or whole house filters, it is not advisable to use these filters until wiring issues have been resolved. This is because most dirty electricity filtering mechanisms can exacerbate the AC magnetic field levels in a home if they are already elevated due to wiring errors!

And when the elevated levels of AC magnetic fields are due to proximity to overhead power lines, there are not too many options. If there is nowhere in the home to relocate the sleeping area(s) away from those high levels, particularly if they are in the Building Biology “extreme level”, sometimes the only option is to move!


Still want to try shielding from the AC magnetic fields?

If you are still considering trying a shielding solution for elevated levels of AC magnetic fields, here is a link for purchasing G-Iron (if grounded, it will also shield from electric fields):


Safe Living Technologies also sells many shielding solutions for other types of electromagnetic radiation.

Use code “HIC-5” at checkout to receive a 5% discount.


Click HERE to schedule a free mini-consult where I can hear your issues and offer a few tips.

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