But getting back to the magnetic field, the wire pairs for each home circuit can be run together because the voltage has been stepped down to 120/240V. As long as the wires remain together, there is no net current, and therefore, no AC magnetic field. The National Electric Code (NEC - or your country’s equivalent) is very carefully crafted to eliminate net current in all buildings. This is aptly demonstrated by Karl Riley in his book, Tracing EMFs in Building Wiring and Grounding14 in which he describes common wiring errors that can lead to unacceptable AC magnetic fields in the home/office building. Electricians, just like everyone else, take shortcuts and make mistakes, but in the case of net current, they rarely understand the consequences of the resulting AC magnetic fields on the health of people in the environment – especially children. The majority of NEC inspectors are probably unaware of this as well, and the mistakes are rarely caught. This is tragic in the sense that a simple gauss meter (measures the magnetic field) and ammeter (measures net current) can reveal the problem quickly before the wiring is encased in the internal structure. Fixing these problems after the fact can be difficult and costly – and you may need a “Karl Riley” to diagnose, locate, and correct the problem. But you can quickly determine if you have a problem with a cheap $50 gauss meter – but more on that later.
When the pair of wires begins to separate, AC magnetic fields develop in the vicinity. All wire pairs must separate widely at the panel box for connection to grid power. This makes the panel box a strong source of AC magnetic fields and explains why you do not want any living areas adjacent to or in the vicinity of the panel box. The wires must also separate at each socket, light fixture, and appliance in the home/office. In the case of appliances, the wires separate internal to the appliance in order to power circuit boards, transformers, heating elements, etc. The more current and separation of the wires - the higher the magnetic field.
Today it is generally and widely accepted that long term exposure to AC magnetic fields in the range of 3-4 milligauss (0.3-0.4 microT) results in a doubling of risk for childhood leukemia. It is, therefore, suggested that long term exposure not exceed 2mG (0.2microT). Many scientists and health organizations suggest that a wider safety margin be applied, reducing this to 0.5-1.0mG (0.05-0.1microT). A healthy safety margin makes sense since there will undoubtedly be periods of much higher exposure, and the dose should be considered cumulative – much like ionizing radiation (radioactivity).
Riley14 relates an interesting (and sad) anecdote from his experience. “The next case is unusual in that it involves a child who developed leukemia in the first year of his life. I was called in to measure the magnetic fields in his crib room since it was next to the service entrance [panel box] closet in a large LA [Los Angeles] estate. I found no unusual field level emanating from the service closet itself, since the equipment was not mounted adjacent to the wall to the child’s room, but a substantial magnetic field was coming from an under-floor source which angled out from the service closet location, ran under the crib and exited near the corner of the room. The field at the crib was 4mG and on the floor where the child crawled it was 12mG [1.2microT]. These values were measured during the day when the only loads were the washer and/or dryer. During the evening the field levels would have been much higher.
The field was due to a net current on the service lateral [circuit] which ran under the floor. I clamped the ammeter around the copper water supply pipe where it entered the building and found it was carrying amperage. Following my recommendation the owner had a plumber insert a dielectric [insulator] coupling in the water pipe down near the water meter near the curb, which was about 100’ from the house. This took the neutral current off the pipe and restored it to the neutral conductor in the service lateral and balanced the magnetic field, thus reducing the magnetic field in the crib room to tenths [of a mG].
The child underwent chemotherapy and for awhile was doing well. Before finishing this revision [of his book] I learned that sadly he had not survived. Was his leukemia due to having been exposed to 4+ mG in his crib and 12+ mG while crawling around on the carpet?”
I’ll include one more of Riley’s anecdotes because it involves a very common wiring error with devastating results in this case: “I was called in by a family living in a desert community north of Barstow CA who had experienced a sudden onset of electrosensitivity [ES]. They were sure something was wrong with the house as they could feel burning sensations, etc and had rashes on their hands which puzzled their doctor. A child born while they lived in the house was born with three kinds of brain damage.
As this was the first case of electrical hypersensitivity I had come in contact with I was cautious if not a little skeptical. But when I measured the house with the lights on I found elevated fields in the master bedroom, the baby’s bedroom, and a field of 82mG at the couch the family gathered together on to watch TV.
After a couple of hours of tracing I found the point where GCs [neutrals] of two circuits had been connected [together]. As mentioned in the text, it was at a duplex receptacle in the master bedroom where one circuit was controlled by a wall switch and the other was always energized. In such receptacles one must break off the tabs connecting the two parts of the receptacle – both the hot tab and the neutral tab. In this case only the hot tab had been broken off. As soon as the receptacle was disconnected the field dropped from 82mG one foot from the wall to below a tenth of a mG at the couch. An 82mG field one foot from the wall is generated by a net current of approximately 12 amps; in this case due mainly to an electric heater used by the family in winter.
Whether the mother’s use of this couch for sleep during pregnancy was related to both the birth defects and hypersensitivity is up to medical specialists to sort out. The hypersensitivity was real as I found by a careful experiment in which I found that the mother was able to tell if a 2mG field was on or off 11 times out of 12, with no external clues from me or the apparatus I used (a covered coil and a silent mercury switch, plus a predetermined randomized on-off sequence).”
