Electrical

Electromagnetic Fields

Electric and magnetic fields are commonly discussed as if they were a single entity termed electromagnetic fields or EMFs. In fact, the two phenomena, although interrelated, are distinctly different and they will be discussed separately in this chapter. Chart 16.1 presents a comparison of the two.

Magnetic Fields

Basic Home Wiring and Net Current

Although the relationship between human health and elevated fields remains contro­versial, there are definite safety concerns as­sociated with wiring techniques that cause magnetic fields. In recognition of such haz­ards, the National Electrical Code has man­dated safer wiring. Your electrician may be puzzled if you declare that you want a home free of all elevated magnetic fields, but if you say you want a home free of net current in compliance with the electrical code, you are
saying the same thing in a language electri­cians understand.

Most household wiring consists of no-volt lines. If you were to peel back the outer insu­lating plastic on a piece of Romex, the most common wiring used, three strands would be revealed — one black, one white, and a third either green or bare copper. The black strand is referred to as the hot wire because it draws electricity from the breaker box or panel and delivers it to light fixtures and appliances. The white wire, called the neutral, returns the elec­tricity to the panel after it is used. The green or bare copper wire is the ground wire. Under normal conditions, it does not carry electric­ity. However, if a malfunction such as a short occurs, it serves as a fail-safe protective de­vice, carrying power back to the ground un­til the breaker is tripped and the power to the faulty circuit is cut off, thereby helping to pre­vent shock and electrocution.

When the electrical system is functioning as it should, the amount of electricity flowing

out to an appliance through the hot wire is equal to the amount of electricity flowing back through the neutral wire. This equal and op­posite flow of current through the wires cre­ates a net current that cancels to zero, which is the desired condition. When, for various rea­sons, unequal supply and return currents are unable to cancel each other out, a net current is present and a magnetic field is created. A second condition that creates net cur­rent with associated magnetic fields occurs when the neutral and hot wires are separated by distance. When Romex wiring is used, the hot and neutral wires run adjacent to one an­other inside the plastic insulating sheathing, allowing them to cancel each other out. In an older wiring system known as knob and tube,

the hot and neutral wires were run on sepa­rate studs. The distance between the wires re­sulted in an uncancelled magnetic field. There was also no grounding. Although now prohib­ited by code, this dangerous system of wiring, along with its associated elevated magnetic fields, is still found in many older homes. The National Electrical Code prohibits the production of net current. This requirement should protect people from elevated mag­netic fields as well. Unfortunately, subtle code violations resulting in the production of net current frequently occur, not only causing el­evated magnetic fields but also increasing the risk of fire and electrocution. We have identified several commonly used wiring techniques that create very high

Chart 16.1: Comparison of Electric and Magnetic Fields

Electric fields	Magnetic fields
Flow in straight lines in all directions from the source unless conductors attract them	Radiate out from the source, flowing in loops
Can be easily shielded	Difficult and expensive to shield {even lead is not effective)
Attracted by conductors such as metal, saltwater bodies, and people	Penetrate all normal building materials
Present when switches for machinery are off or on	Occur only when appliances are switched on and current is flowing
Not widely recognized presently in conventional circles as a health threat	Safe-exposure limits not regulated by the US gov­ernment, though Sweden has set limits
Reportedly affect the nervous system and can cause insomnia, anxiety, depression, aggressive behavior, and a higher risk of leukemia1	Reportedly affect cellular function and have been statistically linked in some studies with increased cancer cell growth rate, Alzheimer’s, miscarriage, and birth defects, while some sensitive individuals report physical reactions
Electrical code permits but does not mandate wiring for reduced electric fields	Electrical code offers protection against exposure to magnetic fields produced by wiring in the structure, with some exceptions
Proper use of electric field meters requires expertise	Easily measured with a gaussmeter

magnetic fields. Although these techniques are considered to be code violations by most code interpreters because they create net current, they often go unnoticed by building inspec­tors. Case studies 16.1 and 16.2 are accounts of such occurrences. Following are specifications for wiring techniques and inspections for pre­venting and detecting elevated magnetic fields in wiring:

• All wiring shall be performed in strict accordance with the National Electrical Code.

• The ganging of neutral wires from differ­ent branch circuits is prohibited.

• Hot and neutral wires must be bundled together, as in Romex. Separate wires fol­lowing separate paths are prohibited.

• Bonding screws shall be removed from the neutral bus of all subpanels per manu­facturer s instructions.

• When wiring a half-switch outlet using two separate breakers for each half of the outlet, the two neutral wires must not make electrical contact. This is accom­plished by breaking off the prescored con­ductive tabs between the two sections of the outlet per manufacturer s instructions.

• Neutral wires on half-switched outlets shall not be mixed. They shall remain paired with corresponding hot wires.

• When wiring enters an electrical box from more than one circuit, care must be taken to ensure that the wires from the differ­ent circuits are isolated from one another so that electricity return paths are not shared. This can be done by installing wir­ing so that all wiring entering an electrical box is from the same circuit.

• At the time of the final electrical instal­

lation, and in the presence of the general contractor, architect, or owner, the electri­cian shall apply a minimum load of three amps to the distal end of each electrical circuit. The home shall be inspected un­der load using a gaussmeter. Any elevated ambient magnetic fields greater than 0.5 milligauss will indicate the presence of net current. These measurements should be taken about a foot away from switches or outlets as the levels right at the switch or outlet will generally be greater than 0.5.

* It is the responsibility of the electrical contractor to locate and eliminate net cur­rent caused by the electrical installation.

• The home shall be reinspected for any net current resulting from the work of other trades in the completed building.

An inspection should be performed after elec­trical installation but before wall surfacing is installed so that any net current resulting from errors in the electrical installation can be determined and easily remedied. The elec­trician should be responsible for correcting these errors. Reinspecting after the surfacing materials are installed will help determine if other trades have caused damage to the elec­trical system. For example, a nail might pene­trate the wiring and cause electrical problems. This damage would not be the fault of the elec­trician, but the electrician would need to cor­rect it.