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The NCB Dial Sweet Spot: How to Find the Best Position of the Blue Dial in Your NCB

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When you find the sweet spot on your NCB dial, it will instantly do two things— reduce current flow AND electric fields to a non-hazardous level.

Using grounding products like mats and sheets is vital if you don’t have the means to ground your body directly on the earth. But the problem is, when you use grounding products, your body is exposed to hazards like contact current, dirty electricity, and electrical fields.

So, to prevent that, we designed the NCB (Nuisance Current Blocker) in collaboration with EMF mitigation expert Andrew McAfee. It stops current from getting to your grounding mat, making it safer for you to ground your body.

But, stopping current creates a separate problem. When you add resistance in the current’s path, it gives a significant rise to electric fields. And that too is a health risk.

And that’s why we’ve also included the blue dial in the NCB. You can use this dial to find the perfect resistance level for current so it doesn’t increase electric fields to hazardous levels.

But how do you know what the perfect resistance level is?

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What Do Grounding Products Do?

Grounding is great. It has many proven benefits, and doing it is pretty simple. You just have to place your body in direct contact with the ground by, say, lying on the grass or walking barefoot.

But many people don’t have the means or the time to ground their bodies on the actual earth’s surface. That’s when products like grounding mats and sheets prove to be the best alternative.

You can learn more about grounding in my post, “What is Grounding? What are the Benefits of Earthing? And How Do I Start?

But though grounding mats and sheets are the best alternatives, a huge problem occurs when you use these products.

Current Electrifies Your Grounding Product

A grounding mat or sheet is designed to simulate outdoor grounding. You just plug it into the ground port of your home outlets.

Grounding provides a path to discharge the excessive charge build-up on your body from your home wiring. That discharge is the relief that you feel when you practice grounding.

But when you use grounding products like mats and sheets, they also expose you to hazards like electric fields, contact current, and dirty electricity. How?

Sources of Current on a Home Grounding System

There are many sources that energize your grounding system, like:

  • Foreign grid-based sources
  • Local sources
  • Home appliances
  • And code violation sources

Because of these, the equipment grounding conductors (EGC) in your home always have some amount of current on them. And this causes anything connected to the outlet to be exposed to this current (including grounding products).

Touching Grounding Products is Like Touching the EGC

Besides the currents from the above sources, there’s one more source that is impossible to remove. This is the NEC-mandated grounded neutral at the service, which is connected to the EGC.

See, the nature of electricity is that if it comes from a source, it needs to return to the same source through the neutral wire. So, the current puts pressure on the grounding system in your home for a path back to the substation.

If your body gets in the returning current’s path, it will flow through your body, as current takes all available paths to return to the source.

This means the floor of your home and anything connected to the earth outside, like the home’s concrete slab, is a conductor for this current.

So, if you, say, stand on the concrete slab and touch a grounded appliance or even a grounded mat, you’ll complete the circuit for that grid return current. In simple words, the current will literally use your body as a wire to return to the source.

If we do touch an equipment grounding conductor (which is attached to all metal-framed
appliances), we will complete a circuit for current to flow between the grounded points.

So, when you use a grounding mat, it’s similar to touching an equipment grounding conductor or a metal-framed appliance. That’s because the grounding mat is connected to the equipment grounding conductor, which contains the grid current.

This type of current is known as contact current or touch current. And it’s not good for your health.

Health Hazards of Contact Current

The Electrical Power Research Institute (EPRI) has done excellent research into contact current and its possible health effects.

They say that if the current flowing through your body exceeds the National Institute of Environmental Health Sciences (NIEHS) threshold, it can create a potential cancer-causing environment in your body.

In 1992, The US congress funded an NIEHS study to figure out why children living near power lines were developing leukemia. Their final report in 1998 revealed one very important number: 1 mV/m.

1 mV/m: The Number to Remember

In Sept. 2001, EPRI published information to help us understand just how much contact current would exceed that NIEHS threshold or limit.

“The results indicate that as little as 5 µA into the hand produces between approximately 20 mV/m (average) to 60 mV/m (95th percentile) within a child’s lower arm bone marrow. Lower electric field values, but still greater than the benchmark 1 mV/m, are expected within the child’s bone marrow at other sites.”

This means that if a current threshold is 5 µA, it exceeds the 1 mV/m benchmark by 20-60 times. So, we need 20-60 times less than 5 µA. Let’s do the math.

= 5 µA

= 5 ÷ 20

= 0.25 µA


= 5 µA

= 5 ÷ 60

= 0.08 µA

So, this is the benchmark. 0.08 µA or below is where NIEHS says could be relatively safe. But why take that chance? Why not say that if ANY measurable current makes it through the body, it’s not at all good?

I mean, we know that a minuscule amount of current flowing through our bodies can cause severe damage. And it’s not just about cancer. There are many health risks that appear before it does.

The properties of current flow are unique and can be equated to or be more damaging than ionizing radiation, say experts.

How to Stop Current from Getting to Your Grounding Product?

So basically, you’d want to stop the current from electrifying your grounding product without ever interfering with its natural movement. And how exactly do you do that?

The NCB from SYB

The NCB or Nuisance Current Blocker is a ground-breaking, patent-pending invention by Andrew McAfee. In collaboration with SYB, Andrew designed this product to make your grounding sessions a safer, healthier experience.

To address the electrical hazards from grounding, we’d want to stop the current right on the grounding conductors. And that’s what the NCB does.

sweet spot ncb dial

Say if you’re using the NCB with a grounding mat. You can simply plug the NCB into the wall outlet and your ground wire into the NCB. And that’s it. The resistor in the NCB stops current from getting to your grounding mat.

Also, the NCB maintains an effective ground-fault path. I’ve explained ground fault paths in-depth in my “Grounding Myths” post. So, give it a read.

In a nutshell, if there’s a cut in your electrical cord or something else goes wrong, your grounding mat can get electrified. If that happens, the NCB activates and sends that current back, which immediately trips the breaker. This can protect you from a potentially damaging or even lethal shock.

The Blue Dial Inside NCB

By plugging the NCB into an outlet and plugging in the grounding mat to the NCB, you will often see a dramatic reduction in the current just from that action. But you’d still want to have control over the level of resistance you put in the path of current. Why?

The Problem with Stopping Current

The blue dial in the NCB lets you change the resistance level (or impedance) that it puts on the current’s path. If you rotate it all the way to the left, you get 14 Ω (ohms) of resistance, and if you rotate it all the way to the right, you get 500 kΩ (500,000 ohms or 500 kilohms) of resistance. And 500 kΩ is, in most cases, enough to bring current flow to 0.0 µA.

But, when you effectively stop current, it increases the electric fields significantly. And that too is not good.

Most of the time, the electric field will go in the opposite direction. If you reduce the current, the electric field increases. If you increase the current flow, the electric field decreases. The more the resistance, the higher the electric field will be, and vice versa.

What we want is the best of both worlds. But most important of all, you want as much reduction as possible in the current flow towards your grounding mat.

So, how far do you turn the dial to get rid of the current but keep the electric field as low as possible? That is where meters like the Fluke 287 and the NFA 1000 come into action.

Finding the Sweet Spot

To find the best level of resistance for the current flow, you need to have these meters. If you don’t want to buy them, you can always get a certified building biologist to give you a visit with these meters and help you set your NCB dial.

Fluke 287 to Measure Lowest Levels of Current

Fluke 287 is a True RMS electronics data logging multimeter, which you can use to measure AC/DC voltage and current, resistance, capacitance, frequency, and temperature.

This multimeter lets you measure extremely low levels of current.

NFA 1000 for Electric Fields

NFA 1000 is an amazing meter that measures AC electric fields and AC magnetic fields in all 3 dimensions (X, Y, and Z axis). It’s one of the most used ELF meters EMF experts use worldwide.

First Measure the Current

When you have the Fluke 287 meter, you’ll have to place it between the contact point on your body (your hand) and your grounding mat.

Note that the NCB needs to be plugged in at this point.

sweet spot ncb dial electric fields vs electrical energy

The Fluke will tell you if your body is completing a circuit for current, as well as how much current is making it past the skin and all the way, internally, through the body.

Your next step will be to see how the NCB can stop the current while preserving the benefits of the grounding mat by rotating the dial and increasing current resistance.

When you stop the current flow, there will also be a significant decrease in the high-frequency dirty electricity (DE). You can say that’s a bonus.

You don’t want to be filtering the power grid’s DE through your body. Stopping the current stops the dirty electricity riding on that current wave.

Once you have checked that the current resistance is working, you can move on to measuring electric fields.  

Start Measuring Electric Fields

Now it’s time to play with the resultant effects of blocking the current flow.

As I already mentioned, the electric field will, most of the time, go in the opposite direction.

Place the NFA 1000 near the body but not touching the body. The NFA 1000 will measure the interaction of the fields to and from your body.

You can place the NFA between your feet on the floor or on a desk between you and your equipment. Don’t put it on your lap or hold it in your hand.

Now start measuring the electric field between your body and a nearby voltage source, like a laptop, lamp, or other energized object, while you play with the NCB dial.

There’s The Sweet Spot

Watch this video of Andrew demonstrating how to set the NCB dial to optimal resistance as well as low electric fields.

Although, if you can’t get the NFA or Fluke to find the sweet spot, Andrew Mcafee says that “most people find the best position of the dial is turned to the left.” 

Parting Pro Tip

One important rule to follow is to first always ground your appliances. Do as much as you can, grounding lamps, computers, and anything around you to pull or attract the electric fields away from you. When you do this, a grounding mat touching your body will do a much better job, and the hazards will be much easier to manage using the NCB.

Another rule, especially in sleeping areas, is to turn the power off. De-energize the circuit or unplug things to remove the electric field as much as possible.

Once you do that, the remaining fields are much easier to manage.

Also, be sure to replace your lamp cords with shielded/grounded cords and use shielded power strips and extension cords as much as possible.

For your laptop, you can add a USB grounding cord into your laptop and a grounding adapter for your ethernet. Basic alligator clips to plug cords are also handy.

Final Thoughts

The NCB is the only product on the market for grounding products that stops current right on the grounding conductor. Each purchase of the NCB also includes a complimentary 15-minute consulting session with its inventor, Andrew McAfee. (A $99 value. Booking details are sent via email 15 minutes after your purchase.)

It’s a small price to pay for your safety and ensuring that you actually benefit from your grounding sessions. So, get yours today at the SYB Store.

Where do you carry your phone?

Want to Slash Your EMF Health Risks?

Good! Learn the one small change you should make right now.

Want to learn more about EMF?

Try these related articles...

About the Author

R Blank is the CEO of Shield Your Body, which he founded in 2012. With hundreds of thousands of customers in over 30 countries, and having been interviewed on platforms including Dr. Phil, ABC news television and ElectricSense, R is an internationally followed expert on issues of EMF, health and safety. He also hosts “The Healthier Tech Podcast”, available Apple, Spotify and all major podcasting platforms. In the past, he served on the faculty at the University of Southern California Viterbi School of Engineering as well as the University of California, Santa Cruz. Previously, R ran a software engineering firm in Los Angeles, producing enterprise-level solutions for blue chip clients including Medtronic, Apple, NBC, Toyota, Disney, Microsoft, the NFL, Ford, IKEA and Mattel. He has spoken at conferences around the world, including in the US, Canada, New Zealand and the Netherlands, and he is the co-author, along with his father Dr. Martin Blank, of ‘Overpowered‘ from Seven Stories Press about the science of health effects of EMF radiation. He has an MBA from the UCLA Anderson School of Management and received his bachelor’s degree, with honors, from Columbia University. He has also studied at Cambridge University in the UK; the University of Salamanca in Spain; and the Institute of Foreign Languages in Nizhny Novgorod, Russia. Read more about R and SYB or connect with R on LinkedIn.

Have a Question?

I take pride in designing great, effective products, based on real, measurable science – AND taking the time to ensure that each and every one of you has the information you need to understand EMF and make informed decisions.

So if you have a question, just email me and ask.

R Blank

R Blank