---

Unlock the crucial, hidden details that define the safety, function, and integrity of your residence in this comprehensive video, “The Secret Language of Your Home.” Don’t guess when it comes to your home’s performance and safety. Empower yourself with the technical knowledge to make informed decisions and ensure a safe, sound, and compliant environment.

---

Everything You Think You Know About Electrical Grounding Is Wrong

Introduction

Most of us use electricity every day, operating on a few “common sense” rules we’ve picked up over the years. We flip switches, plug in devices, and reset breakers, all with a basic understanding of what’s safe and what’s not. But what if the most fundamental rule you’ve ever heard is dangerously wrong?

This is the “original sin” of electrical misunderstanding, the one from which all other dangerous myths flow: the belief that electricity is always trying to get to the ground. For decades, this idea has been the root of countless misconceptions about electrical safety, leading well-intentioned people to make catastrophic mistakes.

This article will debunk several persistent and dangerous myths about electricity. Using insights from renowned electrical safety expert Mike Holt, we will dismantle these flawed beliefs and reveal how electrical circuits truly work. By understanding the real physics, you will gain the knowledge you need to ensure genuine electrical safety for your home and family.

——————————————————————————–

1. Myth: Electricity is Trying to Get to the Ground

The most pervasive myth is that electricity’s primary goal is to reach the earth. The truth is far more specific and is the absolute foundation of all electrical theory.

The fundamental rule is this: Current leaves a source and must return to that same source. This is the definition of an electrical circuit. Whether the source is a DC battery or an AC transformer, the current that leaves it is only trying to get back to it. The circuit must be complete. The earth only becomes part of the circuit if the electrical system is intentionally connected to it (a process called grounding). In that specific case, the earth can be used as a path for the current to travel back to the source, but it is never the destination itself.

As Mike Holt states, this is a core principle we must get right:

“what current does not do… current does not go to ground… current does not go to ground, it goes to where current leaves a source [and must] return [to the] source…”

Understanding this distinction is critical. If you believe electricity is always seeking the earth, you fundamentally misunderstand how to protect yourself from it. Every other electrical safety concept is built on this immutable principle: current returns to its source.

2. Myth: A Ground Rod Will Trip a Breaker During a Fault

This myth is a direct and dangerous consequence of the first one. Many people believe that if a live “hot” wire touches a metal object connected to the earth via a ground rod (like a light pole), the electricity will flow harmlessly into the ground and the circuit breaker will trip. This is completely false and creates a lethal hazard.

The earth is a poor conductor and offers significant resistance. Let’s use a specific example: a 120-volt fault occurs on a metal pole connected to a ground rod with a typical resistance of 25 ohms. Using Ohm’s Law (Current = Voltage / Resistance), we can calculate the current flow: 120 volts / 25 ohms = 4.8 amps. This 4.8 amps of current is far too low to trip a standard 15-amp or 20-amp circuit breaker. The pole would remain energized indefinitely, leaking enough current (4.8 amps) to be lethal, but not enough to trip the breaker. As Mike Holt notes, you could weld with that amount of current, yet the breaker would never know there was a problem.

True safety is achieved by an effective ground-fault current path. This is a dedicated, low-impedance path (a path with very low electrical resistance)—like the green equipment grounding conductor (the “ground wire”)—that connects the metal frame of faulted equipment directly back to the electrical source. This low-resistance path allows a massive amount of current to flow during a fault (often hundreds of amps), which causes the circuit breaker to operate almost instantly. Safety isn’t about giving electricity a path to the earth; it’s about giving it an easy, unobstructed path back to its source so the breaker can do its job.

“How do you make it safe? Turn the circuit off. That’s it. If you have a fault somewhere and something is energized, there’s nothing you can do about it. There’s nothing all you can do is to make it safe. Turn it off.”

3. The Surprising Real Purpose of Grounding

This brings us to the most misunderstood concept in electrical safety. We’ve just established that a ground rod will not trip a breaker and make a fault safe. So why do electricians spend so much time installing them? The answer, rooted in the work of Donald Beeman from his 1952 book Industrial Power Systems Handbook, reveals that the earth connection serves two surprising purposes that have nothing to do with common ground faults and everything to do with massive, unpredictable events like lightning.

1. System Grounding

System grounding involves connecting the system’s power source (such as the windings of a transformer) to the earth. Its primary purpose is to protect equipment from transient overvoltages, which can be caused by events like indirect lightning strikes. When lightning strikes nearby, it can induce a massive voltage onto the electrical conductors. System grounding provides a safe path for this dangerous energy to dissipate into the earth, protecting sensitive equipment from being destroyed.

2. Equipment Grounding

Equipment grounding involves connecting all non-current-carrying metal parts of an electrical system (like conduits, enclosures, and panel boxes) to the earth. Its main purpose is to prevent arcing and side-flashes inside a building during a lightning event. By bonding all metal components together and connecting them to the earth, it ensures they are all at the same electrical potential. This gives any induced energy from a lightning strike a path to the earth, reducing the risk of a fire-starting arc between different metal components.

Crucially, neither of these functions is about tripping a breaker during a standard ground fault. That job belongs entirely to the equipment grounding conductor (the green wire), which provides the low-impedance path back to the source.

To put it simply: The grounding electrode (ground rod) connects your system to the Earth to protect against external events like lightning. The equipment grounding conductor (the green wire) connects a piece of equipment back to the source to protect against internal faults by tripping the breaker. One handles “acts of God,” the other handles equipment failure. Confusing the two is the most dangerous myth of all.

4. Myth: More Grounding is Always Better

Driven by the misconception that grounding equals safety, there’s a common impulse to add “extra” grounding. People often install a supplemental ground rod for sensitive or expensive equipment like CNC machines, generators, or solar arrays, believing it adds another layer of protection. In reality, this can make the equipment more vulnerable.

According to a study by the Electrical Power Research Institute, adding a supplemental ground rod can actually increase the risk of damage. During a nearby lightning strike or a utility system fault, the earth itself can carry a large amount of current, causing a rise in ground potential. An extra ground rod provides a path for this current to flow up from the earth, through the sensitive electronics of the machine, and back to the main service ground, potentially destroying the very equipment it was meant to protect.

“However, field experiments experience a site with the supplemental ground rods have shown that the rod may actually increase the risk of CNC electronic damage. These sites are found to be prone to have damage of internal electronics after thunderstorms or utility system fault.”

The danger arises because the supplemental rod offers a path for errant current from the earth, interfering with the carefully designed closed circuit that runs back to the system’s source.

5. The Shocking Math of an Electric Shock

The severity of an electric shock is determined by the magnitude of the current flowing through the body, not just the voltage. The amount of current that is dangerous is surprisingly small.

Here are the key thresholds for electrical current on the human body:

• Sensation: 0.3 to 0.4 milliamperes (mA) is enough for a person to feel a tingle and say, “I noticed something.”

• Let-Go Threshold: This is the maximum current at which a person can still control their muscles and release their grip. A general rule of thumb is 1 milliampere per 10 pounds of body weight. Above this level, muscles contract uncontrollably, and the person cannot let go.

• Lethal Current: A typical 120-volt shock through a body with 1,000 ohms of resistance produces 120 mA of current (120V / 1000Ω = 0.12A or 120 mA). This is far above the “can’t let go” threshold for any person and can easily be fatal.

So if a standard 15-amp breaker won’t protect you, what will? The answer is a Ground Fault Circuit Interrupter (GFCI). This safety device works by detecting a very small imbalance in the current—meaning some of the current is not returning to the source and is instead leaking through another path, like a person. It operates at 5 mA (plus or minus 1 mA).

The final analysis is sobering: A GFCI’s trip level is designed to be below the “can’t let go” threshold for an average adult, giving them a chance to survive. However, for a small child weighing 50 pounds, their “can’t let go” threshold is only about 5 mA—right at the edge of the GFCI’s protection level.

“GFCI does not mean it’s not going to kill you. It means it probably won’t kill most people but if you’re 50 pounds or lower, we don’t know what’s gonna happen.”

——————————————————————————–

Conclusion

Many deeply ingrained “common sense” ideas about electrical safety are not only wrong but also dangerous. The belief that electricity seeks the ground has led to a widespread misunderstanding of how to protect people and property from electrical hazards.

The single most important takeaway for your safety is this: current is not trying to get to the ground; it is always trying to get back to its source. Real safety comes from providing a clear, low-resistance path for fault current to return to that source, allowing the protective device to operate. With this foundational knowledge, the true purpose of grounding, ground rods, and safety devices like GFCIs becomes clear.

Now that you know the fundamentals, what one thing will you look at differently to ensure the electrical safety of your own home?