Residential Wiring Issues & High Magnetic Fields

by / Thursday, 11 July 2013 / Published in Healthy Building Inspections & Testing
residential wiring issues

PART 3: Tracking Down Unnecessarily Strong, Stray Magnetic Fields

Many people are concerned about the Low Frequency, Alternating Current, Magnetic Field Radiation (further referred to as Magnetic Fields or MF) that is emitted by our modern electrical system and the devices we use every day. The following blog tracks down what can cause residential wiring issues and high magnetic fields.

Although the potential health effects are in dispute, many Building Biologists, myself included, recommend being aware of the magnetic field situation in your home and taking steps to reduce your exposure where practicable, especially in sleeping areas, where 6-8 hours per day is spent in the same location.

In Part One I discussed knob and tube wiring and the potential problems and issues that may arise if your home still contains legacy knob and tube, including strong magnetic fields.

In Part Two, I discussed the benefits of modern wiring, especially Romex, BX or MC, and wiring inside conduit.

In this installment I would like to discuss one of the most common causes of stray, strong magnetic fields in buildings equipped with modern wiring:

Neutral to Ground Connectivity

To be more precise, the issue is really Neutral to Ground Connectivity in a subpanel, or anywhere in the wiring system other than then Main Service Entrance.

Let’s take a step back and discuss where the magnetic fields in our buildings are coming from.

Strong Magnetic Fields inside a home or building can be caused by many factors:

1)   External Sources such as high voltage transmission lines or a large transformer.

2)   Point Sources such as:

  1. Devices with large electric motors, such as fans, refrigerators, clothes washers and dryers.
  2. Devices that draw a large current load, such as electric heaters, electric stovetops, toasters and toaster ovens, microwave ovens, and air conditioners.
  3. Other point sources such as electronic dimmer switches, Red LED screens, and plug in transformers.

3)   Legacy Knob and Tube Wiring (discussed in Part 1)

4)   Improper bonding of the electrical system to the building plumbing

5)   Neutral Current from the neighborhood electrical system (not connected to your own meter) running through the water or gas pipe system into the building electrical system through the plumbing bonding (to be discussed in detail in a future installment).

6)   Wiring Errors in building equipped with modern wiring such as:

  1. Neutral to Neutral connectivity, especially in a junction box.
  2. Miswired 3-way switches, i.e. using 2-wire instead of 3-wire Romex.
  3. Neutral to ground connectivity anywhere in the electrical system EXCEPT in the main service entrance panel.

Most point sources emit a strong magnetic field, but, if well designed and properly wired, should only emit a strong field within a 3-5 foot “bubble” or zone of influence.  I recommend being aware of the point sources in your home and keeping significant point sources away from sleeping areas, work and leisure areas, and any place where occupants congregate for any significant period of time.

Since point sources can be fairly easily identified and exposure controlled, this leaves the more insidious magnetic fields caused by internal building residential wiring issues.  In modern wired buildings, i.e. those not equipped with legacy knob and tube, this is likely due to wiring errors within the electrical system.  Finding these errors can be difficult and time consuming, but once fixed are a permanent solution and can significantly decrease the magnetic field exposure in a building.  Many of these residential wiring issues cause the electrical system to be less efficient and waste electricity and are also electrical and building code violations and can cause excess heat and potential fire hazards, as well as possible shock/electrocution hazards.

residential wiring issues

Electrical Subpanel

Strong magnetic fields due to wiring errors are most often caused by an imbalance between the supply (hot) and return (neutral) current.  Electricity is somewhat like water in that it always wants to take the path of least resistance to complete its circuit.  When neutral current is given multiple paths, the current can split and a portion can return on each path, creating an imbalance along the intended circuit, leading to strong magnetic fields.

The most common wiring error I have observed both in my time as an electrician and as an environmental inspector is by far Neutral to Ground Connectivity.

In order to prevent multiple paths for return current, today’s residential electrical code requires that all ground connections, ground busses, neutrals and neutral busses be separated from each other in the entire electrical system EXCEPT at the main service entrance.  This is intended to give the return neutral current ONE path back to the transformer and keep supply and return current balanced.

If strong magnetic fields are detected and a wiring error is suspected, I recommend isolating the circuit or circuits responsible and then trouble shooting those circuits.

If only one or two circuits seem to be responsible, trace the circuits and examine any junction boxes.  If branches from multiple circuits share the same junction box, the neutrals may all be connected.  If this is the case, an electrician should repair the connections appropriately, so that the neutrals are isolated and only connected to their proper circuit.

It may be that many or all of the circuits in a sub panel are suspect.  This is likely, but not always, caused by the neutral and ground bus being connected in a subpanel.  Sometimes the neutrals and grounds share the same bus.  Other times the bonding screw is activated and bonding the neutral and ground bus together.  Sometimes there is a bonding strap that connects the neutral and ground bus.  If any of these cases are observed, it is code violation and should be repaired.  Often the measured stray magnetic fields will be significantly reduced or disappear altogether.

Sometimes it appears there is a neutral to ground connection somewhere but no errors can be found in the building electrical system.  This situation happened to me recently on an EMF trouble-shooting and repair job, and proved to be a particularly challenging and frustrating situation.

The electricians and I had spent some time and had already found and repaired a subpanel in which the neutral bus was bonded to the ground bus via a bonding strap.  We were still seeing strong magnetic fields and the source appeared to be neutral to ground connectivity somewhere in the garage subpanel circuitry.  After extensive inspection it appeared that every circuit and the subpanel itself was wired properly (and it was!).  Still the stray magnetic fields persisted.

We tracked the issue to the electric clothes dryer, a 220-volt, 2-phase, appliance.  We suspected the outlet was miss-wired, but alas, it too was correct.  However, when the dryer was unplugged, mysteriously all the stray magnetic fields disappeared and no neutral to ground connectivity could be detected.  BINGO!  It appears that the problem was within the appliance itself!

Was the appliance defective?  Was this a manufacturer’s defect? No, the issue was even simpler.  220 Volt supply outlets come in many shapes and sizes, and appliances are designed to be used with several different outlets.  Normally, at least in the United States, the appliances do not come with power cords.  At installation, the installer chooses the cord appropriate for the outlet and wires the cord to the appliance at the time of installation.

residential wiring and magnetic fields


This particular neutral to ground connectivity issue was entirely due to the improper installation of the power cord on this 220 volt electric dryer!

Here is the gist of it.  If a 3-wire outlet is to be used, the cord is connected to the dryer via the Hot 1, Hot 2, and Neutral connections.   There is a strap that connects the ground and neutral in this setup.  If a four-wire outlet is installed, the cord is attached to the dryer via the Hot 1, Hot 2, Neutral, AND Ground connectors on the dryer.  If this setup is used, THE STRAP CONNECTING THE NEUTRAL AND GROUND CONNECTORS IN THE DRYER SHOULD BE REMOVED. 

residential wiring and magnetic fields

Wiring in Dryer


This was NOT done by the installer in our case, effectively connecting the ENTIRE Neutral Bus in the garage subpanel to ground, creating a plethora of stray magnetic field activity.  The good news was that once we removed the gold bonding strap seen in the picture above, ALL neutral to ground connectivity disappeared and all of our strong, stray magnetic fields also dissipated.


Neutral to Ground connectivity faults should be high on the list when investigating an electrical system for residential wiring issues causing strong, stray magnetic fields.  Be diligent in troubleshooting the entire electrical system for neutral to ground connectivity.  But if you are sure that there are no wiring errors and are still detecting neutral to ground connectivity, check the appliances.  Unplug anything plugged into the circuits in question one by one and check for N-G connectivity.  You may be surprised to find the wiring error in an appliance.  This particular problem may be more common than we know.  Please comment if you have ever experienced similar wiring errors inside appliances or other electrical devices.



18 Responses to “Residential Wiring Issues & High Magnetic Fields”

  1. Alex Stadtner says :

    You’re on to a wiring error! I love finding and fixing these. Try unplugging all the appliances and plugs on those two circuits. If the high magnetic fields remain – which they usually do – than you know it’s a wiring error and not a fault somewhere in an appliance. Then you can track each circuit. Somewhere along those two branch circuits you’ll probably find a neutral-to-neutral wiring fault. It may also be two distinct neutral-to-ground faults. You won’t know until you find it. Best to work with a licensed electrician to minimize risk of electrocution. First check behind any switch plate covers where the two circuits may cross paths. Also check in any junction boxes where those two circuits both enter. Sooner or later you’ll find the error and you’ll feel so gratified when you can run both circuits with zero magnetic field readings at the basement ceiling! Good luck.

  2. Elle Mich says :

    I’m having a similar issue. We detected extremely high levels in one area of the home, and directly underneath it in the basement ceiling. When we held the gaussmeter up to the basement ceiling, the reading was over 100! We were able to isolate the problem by turning off two circuit breakers – and the readings went immediately to 0. Now, how do we figure out if its a wiring issue or something plugged into an outlet (such as a dryer in the example noted above)? If it is a wiring issue on that particular circuit, what is usually involved in the fix?

  3. Alex Stadtner says :

    Get a clamp-on amp meter, too, and you can measure the amperage and explain things better to any technicians trying to remedy this EMF problem. When you start talking about EMF their eyes may glaze over… but when you show amperage on something where it’s not supposed to be… most good technicians will jump to attention. Stray current is more frequently a problem than external power lines. People don’t know and without a good EMF meter you never would have known yourself. Congrats on narrowing in on the problem. The fact you turned off your power and the magnetic fields didn’t go away is a great clue in this case. Good thinking!

  4. Alex Stadtner says :

    You’ve got stray current (amperage) coming from the neighborhood, traveling on your shared utilities, and returning to the utility via your excellent Neutral connection at your electric panel. This is more common than you’d like to think. Turn off your main power and check all your incoming utilities. Water is the most common, but you may find amperage (stray current) on your phone or cable, or even your gas line. It’s usually a shared metal water line with the neighborhood. If your neighbor’s panel doesn’t have a good neutral connection the electricity finds the path of least resistance and in this case it’s likely traveling on the water line to your main panel and jumping from the ground bar to the neutral bar. That would explain your high readings. If it’s your water line the most common solution is to install a dielectric coupler on your incoming water main. The plumber has to be careful during this installation because there may be amperage and risk of electrocution or sparking when the water line (current conductor) is severed. But once that pathway is disrupted with an insulated material the magnetic fields should disappear. It’s a very gratifying repair because all of sudden the magnetic fields will almost completely disappear. Good luck, and play safe!

  5. Dan says :

    I have close to about 200 milli-gauss of EMF on my ground rod outside of my house. I’ve also measured around 80 milli-gauss on the ground wire inside the house attached to the water pipe and have measured up to 180 when the furnace is on. Even with my main circuit breaker totally off, I’ve measured 20 milli-gauss. I’ve tested other homes with the same exact meter and have only read about .5 milli-gauss in most cases. The fact that there is so much even with the main panel off makes me think it’s a power company issue. Perhaps a bad transformer or a cracked/dirty insulator, am I on the right track? What could possibly put so much EMF on my ground wire?

  6. Alex Stadtner says :

    Interesting case. There may be a wiring error or hidden load in the building (or neighborhood) that is somehow impacting magnetic fields and your electricity consumption. The magnetism you’re talking about – like refrigerator magnets – is Direct Current (DC) magnetism and household electricity and what is generally referred to as EMF are Alternating Current (AC). If standard metallic items are becoming magnetized I would also be concerned. There are meters for such things, but generally when people talk about measuring magnetic fields they’re talking about AC magnetic fields. You might consider hiring an EMF consultant to come and take some readings and test to see if there are wiring errors or significant AC magnetic fields. You may also be uniquely positioned over a mineral deposit that creates significant DC magnetic fields. I think you may need an EMF expert to do a survey. Please do let me know how things turn out. Curious case.

  7. Katherine says :

    We have been having things in our house become magnetic that should not be that way. I have stainless steel scissors, pins, needles, crochet hooks all become magnified. I do not understand just why. When we moved into this place the electric bills was three times what others bills were and while they had big families, it was just the two of us. My husband had to rewire part of our wires after we had a garage fore which was not related to this problem as far as we know. After rewiring the electric bill went down considerably. He also had put in a new junction box when he did the rewiring. There is one room that was built at a later time than the rest of the house, and it has it’s own heat and air system, and we think perhaps they may have wired it wrong. We think maybe there is a relationship between the electricity and the magnetic fields it may be making. Is that possible?

  8. Alex Stadtner says :

    It’s rather involved to do electrical quality control testing for magnetic fields.
    I don’t suggest anyone do this unless they’re a licensed electrician, but one method is to remove each neutral one at a time from the neutral bus and test for continuity against the neutral and ground bus. If there’s continuity – you’ve got a wiring error that could result in stray current throughout the building’s electrical and plumbing systems.
    Another less precise approach is to test for magnetic fields with various appliances and loads on verses off.
    Magnetic fields from balanced loads drop off much more quickly than magnetic fields from wiring errors.
    There are calculations you can perform to estimate the drop-off rate and estimate whether or not it’s a wiring error or simply a high load on a balanced wire. If you do a lot of EMF testing you’ll get a sense for what is a wiring error from simply using a Gauss meter, but that takes time and experience.
    Good luck, play safe.

  9. Bill says :

    How would recommend testing that electrician wired things correctly? I have an electrician completely rewired my electricity with bx. I do measure higher Magnetic fields by the 3 and 4 way switches. I am not sure if there will always be some even if wired correctly.

  10. Alex Stadtner says :

    Most electricians know next to nothing about electromagnetic fields. If you want a reading of EMF, try finding a local Building Biologist via this link. They will probably also know electricians that are experienced finding wiring errors, etc. If it’s anything other than high electric fields or high magnetic fields from wiring errors, you’ll be better served by hiring a Building Biologist than an electrician. In either case – you probably need a Building Biologist or expert EMF consultant.
    Good luck,

  11. Ann Malley says :

    I need an electrician in Manhattan NYC that can detect activity in my apt. of EMF, there is intense buzzing and flow of electricity in my apt. It is very painful leaving me with headaches and burning and swelling. Please recommend someone to take a reading.
    Thank you.

  12. Alex Stadtner says :

    We do not recommend EMF testing meters or detectors. We are a service company and generally do not sell products – EMF meters or otherwise.

  13. RD says :

    Where do you recommend recommend for EMF meter testing

  14. Mitigating and Eliminating Magnetic EMFs – A Mom’s Guide (part 4) - Organic Housewife says :

    […] Neutral to ground connectivity anywhere in the electrical system EXCEPT in the main service entrance panel.  (source) […]

  15. Francine says :

    I’ve just started on this path and can only tell you what has worked thus far for me on some things. When I started, I tested all my bedroom outlets for magnetic. I had several outlets over 20nT and one that was nearly 600. As an experiment, I opened the outlets up and found that on the one circuit, most of the outlets were wired such that the line on the left was wired to the top receptacle and the wire on the right wired to the bottom receptacle. The high outlets had wired “crossing” the receptacles – for example, the hot wire from one line attached to the top receptacle and the neutral from the same line attached to the bottom. When I changed the wiring to a line connecting to the top or bottom only, numbers came down. I also had “hot” spots of magnetic in the middle of my floors and at the head of my stairs. All these went away when I made the simple wiring change. I did have a few outlets that were being used as junction boxes as well – meaning 3 lines connected to the outlet using both the screws and plug in holes in the back. As an experiment on those to see how it affected the readings, I changed the wiring configurations and got readings of 20, 150, 600, etc depending on the configuration. I replaced those outlets and pigtailed two lines together so that only 2 lines connected to the outlet. Also, GFCI’s that read high, were replaced.

  16. Thanks David…

    This BLOG is very informative. We have found NANOBIOPLEX TUBES to be very effective in managing and solving this problem. Simply apply them to the HOT & Neutral wires in the breaker box. You can also apply them to the GAS, PROPANE & WATER LINES.

  17. Elec Excel says :

    Quite the comprehensive guide you’ve produced here David, thanks for all the information.

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