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Imagine that you just purchased a
gauss-meter to check the level of electromagnetic fields inside your
home or office. There are no visible power lines outside; they’re buried
underground. Therefore, you don’t expect any significant readings but
the readings are high. You turn off the TV. But the reading is still
high. You think the meter is broken. You go outside and the readings are
almost zero. You go back indoors and high readings return. What’s going
on?
It is safe to say there are probably errors in the installation of
electrical wiring in your building, a common problem. In some cases the
wiring errors can cause a higher level indoors than standing under power
lines outdoors. According to Karl Riley, author of Tracing EMFs in
Building Wiring and Grounding, almost 70% of elevated magnetic
fields in homes, offices, and schools are due to wiring errors and
grounding problems – not power lines. Only about 20% of the time is
power lines responsible10. These wiring errors are simple
mistakes that electricians routinely make without knowing it. How do
these errors happen?
If you look at a piece of electrical wiring you will see a black wire
and a white wire. The black wire carries electrical current to where it
is needed and the white wire completes the circuit, taking the current
back to the fuse box. The black wire is called “hot” because it will
shock you if you touch it. The white wire is referred to as neutral.
Technically the neutral wire is not neutral. It carries current, just at
a lower voltage that will not shock you.
When current flows on the black wire to where it’s needed, a magnetic
field is created. This is a beautiful phenomenon of the universe, a law
of physics that simply is. This phenomenon is actually what is used to
generate electricity. When magnets are rotated around copper wires at
the power utility plant electricity is produced. There would be a high
magnetic field everywhere the black wire carries electricity to inside
the building except for the white wire. As current flows back to the
fuse box on the white wire, a field is created of the same intensity
that cancels the field. As long current returns on the same set of
wiring as the black wire it came with, no net magnetic field is created
inside the building.
How Errors Happen
Electricians are only allowed by
code to connect so many outlets with the same wire going to a given
circuit. Sometimes when installing wiring in new construction they end a
circuit and start a new one in the same outlet box. They tie all the
white wires together inside an electrical box. This is ok for wires of
the same circuit but not ok for wires from different circuits. Commonly
this occurs where there is a set of switches on a wall. When this
happens the current on one set of wire does not return with the wiring
it came from. It returns on the wires from both circuits creating a net
magnetic field where ever those wires go. The level may be negligible to
large depending on how much current is flowing, i.e., how many lights
are turned on.
In one an example of how small wiring errors can result in high magnetic
fields, workers found a “hot spot” due to an emergency light that was
improperly wired in a three year old school. The parents were concerned
about high magnetic fields from the nearby power lines. Readings taken
at the edge of the playground near the power lines averaged 8 mG, much
lower than the 50 mG in the area near improperly wired light.11
Other types of wiring errors
Tying white wires of different
circuits together is just one of several types of wiring errors that may
cause elevated magnetic fields.
Three way-switches are another common place wiring errors are found.
Ceiling fans that are controlled with three-way switches and have a
light present a special problem. There is only one neutral for both the
fan and the light. If you want your electrician to understand what you
are talking about tell him, "Three-way switch travelers must be
3-conductor and not two-conductor."
A less frequent but serious problem errors occur at sub-panels. Most
homes don’t have sub panels and this applies more to apartment buildings
and offices. The tab connecting the ground to the neutral bus is not
removed at sub-panels. This allows return electricity from one sub-panel
to get on the grounding system of the other sub panels and travel
everywhere.
Eliminating Wiring Errors
It is easy to check for wiring
errors and magnetic fields in your home. You will need a gauss meter. A
list of suppliers is included at the end of this chapter. It is an
easier meter to use. Simply turn it on read the number displayed. The
testing procedure to check your home is as follows:
- Turn on ALL the lights in the entire
house. It is important to turn on everything you possibly can. If
you don’t test with everything turned on there may be something
causing a problem that you’re not detecting.
- With all the lights on, go from room
to room and turn on and off each light or fan switch while looking
at the meter. It is normal for the meter to twitch but if the
reading goes up or down and stays there that indicates a possible
wiring error.
Consult an electrician to determine which
circuits are affected and to make the repairs. Most electricians are not
familiar with the concept of wiring errors causing high magnetic fields.
When you talk to the electrician use the term “net current”. Tell them
there is “net current” as a result of wiring errors that is being
detected by a change in the level of magnetic field when the lights are
turned on. Net current is not allowed by the national electric code.
Refer them to the National Electric Code13 or
www.mikeholt.com, a useful website for electricians discussing code
matters. Wiring errors are not caught by the building inspector because
they are difficult to see during a walk-though inspection.
Suggested Reading
For a more complete list and
explanation of the types of wiring errors that cause high magnetic
fields, see Tracing EMFs in Building Wiring and Grounding
by Karl Riley. If you have a difficult problem that needs solving, Karl
can be reached at by e-mail at
kriley3@bellsouth.net. His DVD can be purchased at
magneticsciences.com and mikeholt.com
The on-line Electromagnetic Field Course offered by the Institute for
Building Biologie & Ecology is also very useful especially for those who
want to do testing surveys. The institute offers what are probably the
most comprehensive training seminars on the topic in the county. Contact
www.bau-biologieusa.com (727) 461-4371
Resources
To purchase Gauss Meters and
Testing Equipment
For a list of professionals who are
trained in performing electro-magnetic field surveys
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