Physical Science - Other

Grounding Cone of Protection

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Planning can result in a strong grounding cone of protection (GCP) Model. Gaps inside the base of the primary grounding cone of protection may be partially filled or covered by secondary grounding cones of protection that begin at sub-panels and interior integrated services bonding points (ISBPs).

A strong GCP Model implemented at a facility prevents "dunking," or exposing, occupants at a facility in a flux of electromagnetic energy fields. Dunking results in a collapse of the grounding cone of protection.

Without planning, a weak GCP Model results. For example, neither the cone nor its base will completely protect the interior unless designed to do so. This means that the grounding cone of protection will have mostly gaps which can be closed by extraordinary shielding measures. The lack of an ISBP means wider gaps will be present.

Collapsing the Cone Creates Imminent Risk

One might conclude that a conductive exterior would strengthen and enhance the grounding cone of protection at a facility. In fact, a nonconductive exterior is just as important to maintaining a proper GCP model, because it avoids the risk of improper connections.

The exterior beyond the boundary of the grounding cone of protection consists of air and non-conductive materials such as wood, brick and mortar, and glass. This nonconductive barrier prevents the collapse of the grounding cone of protection and its GCP Model. Current flow is diverted or channeled properly into the electrical power service entrance (ESE) and the grounding electrode system (GES).

Whether indoors or out, improper shielding, bonding or grounding can collapse the grounding cone of protection and change the GCP Model. Instead of one vertex serving as the sole point connecting Earth to the facility, multiple grounding pathways that bypass the GES will permit current flow to occur at different magnitudes and amplitudes all around. This poses hazards to the facility and to its occupants within.

In this situation, a facility above ground will behave as if the Earth were electrically at the same altitude as the facility. This means that all of the noise and current flux below ground and at the GES passes through the facility near the occupants. This creates an imminent risk of electrical shock, fire, and breakdown of the facility from excessive current flow.

A partial solution to this problem is the ESE, which is designated as the sole electrical go-between for the interior of the earth and the interior of the facility. The complementary device that completes our solution is the ISBP. Our solution works because the entire facility is electrically insulated and isolated from the earth, except through this one conductive pathway, represented by the portion of the cone closest to the vertex. Any current flow is therefore integrated and balanced.

The ESE is a funnel-shaped section of the grounding cone very near to the GES vertex. The ideal ISBP will occupy the funnel-shaped section in between them.


The GCP Model shows us where to anticipate hazards and close gaps.

Improper bonding and grounding can collapse the grounding cone of protection and change the GCP Model. Such an event places the facility and occupants at imminent risk.

The GCP Model includes one primary grounding cone of protection. Secondary cones can be stacked within the primary and thus strengthen the grounding cone of protection.

The ESE and ISBP aid in maintaining a strong grounding cone of protection.

More about this author: Raleigh Stout

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