Low EMF Home Wiring: Key Lessons
Let’s take a closer look at one of the most important parts of building a healthier home: home wiring. For this walkthrough, I’m joined by Kevin Fortney of Fortney Electric, who played a key role in wiring the house we’re standing in today.
If you’re planning a low-EMF home, the electrical phase is one of the most critical steps. Done right, it can help reduce unnecessary magnetic fields throughout the house. Done wrong, it can create elevated fields in rooms where people sleep, work, and spend time every day.
In this post, we’re going to walk through some of the biggest wiring considerations we focused on during this build, including sub panels, neutral and ground separation, three-way switches, neutrals from different circuits, feeder wiring, and shielding strategies.
Why Neutral And Ground Separation Matters In A Low EMF Home
One of the first things Kevin explains is the importance of the neutral bonding screw in a subpanel. This is typically a green screw that comes with many electrical panels. In a sub panel, that bonding screw must be removed so the neutral and ground are not bonded together there.
The neutral and ground should be bonded at only one location: the main service disconnect, where power enters from the utility company. In this house, the bonding point is down at the main service near the meter, not in the house subpanel.
If neutral and ground are bonded together at more than one point, it is not only a code issue; it can also create higher magnetic fields in the house. Kevin points out that this is a common mistake during the wiring phase, so homeowners and electricians should verify it carefully.
Why Panel Choice Matters: The Siemens PN Panel
Another major consideration is how close the neutral and hot conductors stay to each other inside the panel. The greater the separation between those wires, the greater the magnetic field.
That is one of the reasons we wanted a Siemens PN panel. Kevin explains that the Siemens PN design features neutral bars running up both sides of the panel, which makes it easier to keep the neutral and hot conductors as close together as possible until they terminate. The goal is to keep those paths side by side for as long as possible to help minimize magnetic fields.
Even with a better panel design, there can still be a field around the panel itself. In our case, when measuring with a Gauss meter, a field still extended roughly 36 inches around the panel. That is why panel location is so important in a low EMF home. You do not want a panel placed right next to a bed, sitting area, or other occupied space if it can be avoided.
The Sub Feed And Why Conductor Separation Creates Magnetic Fields
The same basic principle applies to the feeder wires coming into the house. If the conductors are too far apart, the magnetic field increases.
Kevin explains that when the hot and neutral conductors stay close together, their fields tend to cancel each other out. But as the separation increases, the magnetic field grows. This is especially important in the feeder wiring that supplies power from the main service to the house.
In our project, the main meter and service equipment were located well away from the house, so we needed a disconnect at the house as well. That meant paying close attention to how those feeder conductors entered and ran through the structure.
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Helpful Books For Planning A Low EMF Home
If you are building with low EMF goals in mind, two resources we found especially helpful were Tracing EMFs in Building Wiring and Grounding by Karl Riley and Prescriptions for a Healthy House (4th Edition).
Both books helped guide decisions during the project. Tracing EMFs in Building Wiring and Grounding was a useful technical reference throughout the process, and Prescriptions for a Healthy House includes a section on electrical design with recommendations and parameters to consider when wiring a healthier home.
Three-Way Switches And The Danger Of Improperly Tied Neutrals
One of the more important technical topics we covered was three-way switches and the issue of incorrectly tying neutrals together.
This box had two circuits, which is something you generally avoid in a low-EMF build. But when multiple circuits end up in the same box, the neutrals must be handled correctly.
Kevin explains that if neutrals belong to different circuits and the breakers are not tied together, those neutrals must be kept separate. In the example we looked at, one neutral was intentionally not tied to the others because it was on the switch-leg side of a three-way switch. When that neutral was tied in the standard way, the EMF reading was much higher. When it was kept separate, traveled the same path as the travelers, and switched legs, the EMF dropped significantly.
This is one of those details that may not stand out in a conventional build, but in a low EMF home, it can make a major difference.
How Three-Way Switch Wiring Was Handled In This House
Kevin walked through the wiring setup used in the house. Because we were using 20-amp circuits, the home wiring was done with 12-2 and 12-3 cable.
The typical layout in this case was 12-2 from the panel to the first switch location, 12-3 between the three-way switches for the travelers, and 12-2 from the switch location to the light.
The unusual part was how the neutrals were handled. In a standard installation, neutrals from the same circuit might be tied together in the box. But in this setup, it would have created a larger magnetic field because the current would have returned to the panel via different neutral paths.
When current takes different return paths, the hot and neutral are no longer canceling each other the way they should. That can create a large magnetic field in the room. Kevin notes that in some cases, this kind of issue can create readings of around 4 milligauss across a room, effectively creating a field people live in.
The good news is that it is often a fixable problem. By tracing the net current and correcting how the neutrals are connected, you can often eliminate that field.
Why Ganging Neutrals From Different Circuits Is A Problem
We also discussed ganging neutrals from different circuits, which is another major problem in low-EMF home wiring.
Kevin explains that if the breakers are not tied together, tying the neutrals of different circuits together is not code. From an EMF standpoint, it also creates a larger magnetic field. The reason is simple: current can split and return along multiple paths depending on resistance and impedance, meaning the hot and neutral conductors are no longer balanced as they should be.
That imbalance creates fields in the room and throughout the house. The fix is to keep the neutrals properly separated and ensure each circuit’s neutral stays with its own circuit, unless the wiring method specifically and correctly allows otherwise.
At The Main Service: Where Neutral And Ground Should Bond
Later in the walkthrough, we went down to the main service equipment. This home had a 400-amp service coming in from the utility company, split into two 200-amp disconnects.
This is the one place where the neutral and ground should be bonded. Kevin showed us the grounding screw that bonds the neutral bar to the grounding system, which, in this case, ties into the ground rods.
To verify that the system was set up correctly, Kevin isolated the neutral and checked continuity between neutral and ground. If there had been a tone, that would have indicated an unwanted neutral-to-ground connection somewhere else in the system. Since there was no tone, it told us there was no unintended connection beyond that point up at the house.
This was a huge time-saver because it allowed us to confirm that the branch circuits and subpanel did not have an improper neutral-ground bond without having to disconnect and inspect every circuit individually.
It also matters because unwanted neutral-to-ground connections can send current onto metal components in the house, including potentially gas lines or other conductive paths, which can create unbalanced loads and unwanted fields.
Why We Used Rigid Conduit For The Feeder
Another big decision in this build was how to route the feeder supplying the house sub-panel and disconnect.
Because that feeder carries such a high current load, we wanted to minimize the magnetic field it would produce inside the structure. Kevin explains that this is why we chose rigid conduit instead of EMT or MC cable for that run.
Rigid conduit has a much thicker metal wall than EMT or MC cable, which helps reduce the magnetic field. In our case, the rigid conduit was about one-eighth inch thick. It was assembled with a combination of threaded connections and compression couplers, depending on the section.
We also noticed that the bends and radii in the conduit sometimes showed somewhat higher readings, likely because the conductors were separating slightly inside those curved sections. Still, the rigid conduit made a major difference. Compared to an MC cable feeder, the magnetic field from the feeder was roughly ten times lower on the floor above.
Adding Steel Shielding Above The Feeder
Even with the rigid conduit, we wanted to lower the field even further. So above the feeder run, we installed plate steel shielding. That extra shielding reduced the magnetic field in the floor to around 0.2 milligauss, a significant improvement.
We also intentionally ran that feeder at the very bottom of the floor trusses. That gave us roughly 18 extra inches of separation from the occupied floor above. In low EMF design, distance is one of your best tools. The more space you can create between high-current wiring and living areas, the lower the exposure tends to be.
Final Thoughts On Low EMF Electrical Planning
There are many ways standard wiring practices can unintentionally create elevated magnetic fields in a newly built custom home. This is why planning matters so much when you are building for low EMF performance.
The details Kevin Fortney of Fortney Electric walked through in this project—removing the bonding screw in the sub panel, keeping neutral and hot conductors close together, choosing a Siemens PN panel, properly handling 12-2 and 12-3 wiring for three-way switches, separating neutrals correctly, bonding neutral and ground only at the main service, and using rigid conduit with plate steel shielding—all played an important role in reducing unnecessary fields in this house.
If you are serious about building a healthier home, you can request a consultation with us. We have offices in Ramona, California, serving the San Diego County area, and Middleton, Idaho, serving the Boise Metro area. You can also explore our comprehensive collection of similar videos on our YouTube channel, The Real Property Show.
