Grounding, also known as Earthing, is the practice of physically connecting the human body to the Earth’s surface. This connection allows the body to absorb a supply of free electrons from the Earth. The benefit of this electron transfer is the neutralization of positively charged free radicals within the body, which may contribute to inflammation and other health issues. This process brings the body to the same electrical potential as the Earth, which is a stable, neutral reference point.
How Grounding Works
The Earth acts as a vast reservoir of mobile, negatively charged electrons. This supply maintains the planet’s surface at a stable negative electrical potential. When a conductive object, including the human body, makes direct contact with the Earth, the electrical potential difference causes a transfer of charge.
The human body often accumulates a slight positive charge, especially when insulated by modern footwear and flooring. This charge is a result of lifestyle and exposure to various forms of electromagnetic “noise.” By connecting to the Earth, the body absorbs free electrons until its electrical potential equalizes with the ground. This transfer relies on conductivity, which is the ability of a material to allow the flow of electrical charge. Conversely, a material with high resistivity acts as an insulator, blocking electron transfer.
The Conductivity of Concrete
Whether concrete permits grounding depends entirely on its composition and, more importantly, its moisture content. Concrete is a mixture of cement, water, and aggregates, and when completely dry, it has extremely high resistivity. Dry concrete lacks the mobile ions necessary to carry an electrical charge, effectively acting as an insulator with a resistivity that can be on the order of 10^12 ohm-millimeters.
The presence of water significantly changes concrete’s electrical behavior. Water reacts with the cement to form ions that move under an electric field, making the material conductive. Moist or wet concrete can behave like a semiconductor, with resistivity dropping dramatically. Therefore, thin, damp concrete poured directly on the ground may offer a weak conductive path.
A variable is the presence of steel rebar or wire mesh used for reinforcement inside concrete slabs. Steel is highly conductive, and if this metal framework contacts the damp earth beneath the slab, it can create an indirect path for electron flow. Ultimately, dry, sealed, or painted concrete is ineffective for grounding. Damp, unsealed concrete poured directly on the ground is highly variable and questionable as a reliable conductive surface.
Where You Can and Cannot Ground
Effective grounding requires direct contact with surfaces that possess high electrical conductivity. Natural ground, such as damp soil, earth, and mud, is highly effective because it is rich in mineral ions and holds moisture, which facilitates electron flow. Walking barefoot on natural grass, especially when wet, also provides an excellent connection.
Natural bodies of water, including lakes, rivers, and the ocean, are also highly conductive due to their mineral and salt content. Moist sand on a beach is an excellent medium for electron transfer. These natural surfaces provide the most consistent and reliable path for the body to absorb the Earth’s electrons.
Conversely, many modern surfaces act as electrical insulators, completely blocking the electron exchange. Common surfaces that prevent grounding possess extremely high resistivity and inhibit the flow of electrical charge. Sealed or painted concrete is ineffective because the sealant acts as an insulating barrier, regardless of the slab’s moisture content.
Insulating Surfaces
The following common surfaces prevent grounding:
- Wood
- Asphalt
- Vinyl
- Plastic
- Ceramic tile