ELF Magnetic Fields
Magnetic fields are present with electricity actually flowing through a wire or a metallic path of some kind. Strong magnetic fields will penetrate walls and people.
My “neighborhood” magnetic fields are roughly 0.20 mG. Inside of the house varied from 0.13 mg to 0.60 mG in the kitchen within reasonable proximity to appliances.
I really do not like this EMF. The Magnetic fields EMF is difficult to understand and in some cases nearly impossible to mitigate. The only positive with magnetic fields is that distance makes it safer. The farther away you are from the source, the better and in some cases you only need a few feet.
Exterior magnetic field sources include high voltage power lines, transformers, neighborhood distribution lines, etc. Magnetic fields from exterior sources are nearly impossible to mitigate. Distance is key. External magnetic EMF is very complex, if you live close to a power line or a neighborhood distribution line, this is a good starting point. And another resource. There are many factors determining the strength of the field – distance between ‘Hot’ and ‘Neutral’ conductors of the transmission lines, the amperage, season (summer/winter) and even the time of day (how much electricity is used at a particular time of day with morning and evenings being the highest). Neighborhood distribution line magnetic fields also vary in strength; factors like number of homes supplied, amperage, and the location of house in relation to the main substation (the closer your home is to the ‘end’ of the distribution line, the lesser the magnetic fields).
Internal magnetic field sources include control boards/centers of major home appliances, and smaller home appliances, wiring errors, electrical panels and sub panels and some electronics (heaters, fans, toasters, etc). The type of home electrical wiring also play a significant role; “An amazing fact of EMF physics is that magnetic fields can “cancel themselves out.” Modern day 3-wire or 4-wire cabling has lead to reduced ambient magnetic fields because the Hots and Neutrals are so close together the magnetic fields mostly cancel themselves out and cannot be measured far from the electrical cable. Buildings with active Knob-and-Tube wiring generally have higher ambient magnetic fields because of the distance between the Hot and Neutral of each circuit. This is only true when there is a load on the circuit.” (source)
Some strong magnetic fields may find the path of least resistance and enter or travel through the house via plumbing system, data cables including phone line, electrical grounding system, metallic conductors etc. The higher the flow of electricity and the closer you are, the stronger the magnetic field.
Building Biology, guidelines for safe magnetic fields EMF levels in sleeping areas:
What we did and some interesting observations:
The first step is to measure the outside “neighborhood” magnetic field. If it is within the safe range, move on to internal readings.
We have not done much with magnetic fields EMF. The approach here, find the source and avoid it. Exterior magnetic field radiation is difficult and very cost prohibitive to shield. Interior sources from wiring errors, home electronics, major appliances are fairly easy to avoid.
I bought this Magnetic Fields meter to fine-tune my EMF mitigation. When testing interior fields, shut off all lights and do not stand next to any appliances or any major electronics. The reading will increase as you approach an object giving off a magnetic field and will decrease as you walk away from it. Most electronic subjects will emit a field within 3-5 feet radius.
Some light switches may have wiring errors and will produce magnetic fields. In very simple terms, to test for wiring errors, stand several feet away from a light switch and turn it ‘on’ – if the reading went up, there is a wiring error.
“To be more precise, the issue is really Neutral to Ground Connectivity in a sub panel, or anywhere in the wiring system other than then Main Service Entrance.”
- Neutral to Neutral connectivity, especially in a junction box.
- Miswired 3-way switches, i.e. using 2-wire instead of 3-wire Romex.
- Neutral to ground connectivity anywhere in the electrical system EXCEPT in the main service entrance panel. (source)
Wiring errors are sometimes small and sometimes create a very drastic change in a magnetic field. Print these (part 1, part 2 and part 3) for your electrician, especially Part 3 as most electricians will have no idea what you are talking about. Having a meter to check if the problem was fixed is also essential. This video may also explain what a wiring error is to an electrician. These resources are excellent if you are building a house!
With major appliances, like a dishwasher, the control board is usually inside the top part of the door. The measurement around that area would go up to 200 mG.. The target, “safe” measurement is under 0.5 mG,. On the left is a measurement mid-door; notice the magnetic field increasing as I approach the control panel of the dishwasher. This is so disappointing because usually kids love to help with loading and unloading the dishwasher… And that dishwasher is usually near a sink; most of us spend some time in that area daily…
With the refrigerators, their control boards are in the back so actually standing in front of the refrigerator is completely fine as far as magnetic fields are concerned.
Generally, magnetic fields are present within 3-5 feet of a working appliance and/or an electrical panel or sub panel.
My interior measurnments were anywhere from 0.13 mG to 0.6 mG close to sources, but generally, mid-kitchen reading was round 0.2 mG – 0.29 mG. I measured some of the magnetic EMF fields emitted from some of my appliances and electronics… Some readings were actually the same for when an appliance was ‘On’ or ‘Off’.
| mG | 1-foot distance | 3-feet distance | 4-feet distance | 10 -feet | |
| Dishwasher On or Off | 193.25 | 7.88 | 2.18 | .48 | |
| Stovetop On or Off | 95.03 | 1.05 | .33 | .28 | |
| Computer On | 23.30 | 3.27 | .39 | .20 | |
| Corded Phone On | 8.12 | .47 | .28 | .25 | |
| Wall Oven Off | .51 | .24 | .23 | .23 | |
| Wall Oven On | 17.44 | 5.9 | 2.23 | .75 | .43 |
| Hairdryer On | 137.79 | 5.81 | 1.27 | .84 | |
| Microwave On | Front 103.28
Near Control Panel 216.15 |
75.46 | 40.10 | 2.37 | .53 |
| Microwave Off | Front 4.89
Near Control Panel 149.39 |
3.85 | .38 | .27 |
The microwave. Gasp! Yes, I have one but rarely use it. Sometimes, I need to reheat my food quickly and cannot forego the convenience. I do not use the microwave for my children’s food however. In an off position, it is actually not bad at all. The reading by the control panel are very high and the control panel is actually away from the dials. When the microwave is on, the readings are astronomical, and are within an acceptable range 12-14 feet away. I was surprised that in addition to magnetic fields, the microwave in the ‘On’ position also emits radiofriequency waves, upwards of 1,000 µW/m2; moreover, these radiofrequency waves do not decrease with distance. So if you do have a microwave and you do use it, make sure the children are nowhere near.
Yet another source magnetic fields are currents traveling through metallic paths like a wire or a metallic pipe. In our case, there is a house (or houses) in our neighborhood that is (are) grounded to its metallic water pipe and we are getting those electrical currents coming in. Typically, a house is grounded to grounding rods near the electrical panel but sometimes people ground to the metallic water pipe and sometimes they do both. It could happen to a natural gas line as well. We are in the midst of mitigating this issue… Finding an electrician and a plumber that will take the concerns seriously and work together is a real challenge. In this case study, “The electrician was guided to install a dedicated earth ground to bond the metal water pipe to and a plumber was brought in to install a dielectric union to insulate the house ground from the metal water main line.” I also found some informative snippets here. A qualified EMF consultant will be able to guide you through the process in your individual situation.
An interesting link to magnetic fields on Bay Area Rapid Transit. If you ride the train, this is a good quick read.
Mitigating ELF Magnetic Fields on a budget
Not much can be done here. The proximity to power lines and neighborhood distribution lines cannot be changed. Visit Antenna Search to determine just how bad the magnetic fields could be, but it varies based on multiple factors.
Keep away from major appliances. Other than that, this one requires a meter to determine if there is a problem.
Related Reading:
Mitigating and Eliminating EMFs – A Mom’s Guide (part 1)
Mitigating and Eliminating Radiofrequency (WiFi) EMFs – A Mom’s Guide (part 2)
Mitigating and Eliminating Electric EMFs – A Mom’s Guide (part 3)
Mitigating and Eliminating Dirty Electricity – A Mom’s Guide (part 5)
