Solution Summary: Ground Ring
To protect buildings and electrical equipment from damages caused by electrical surges, a ring ground could be placed under buildings during construction phase.
Description:
A ground ring is a solution that provides the means to connect all elements of the grounding electrode system to increase the safety of the workers at a construction site. The Hierarchy of Control (HOC) is a well-known framework to evaluate the performance of safety solutions in Occupational Safety and Health (OSH) research (Wakefield et al. 2014). HOC consists of five levels of effectiveness: (1) Elimination, (2) Substitution, (3) Engineering Controls, (4) Administrative Controls, (5) Personal Protective Equipment; with elimination being the most effective. At the third level, engineering controls “use safeguarding technology to place a barrier to keep a hazard from reaching workers” (Zhao et al. 2015).
Grounding is the “process of removing excess of charge on an object by means of transfer of electrons between it and another object of substantial size. The ground is capable of transferring electrons to or receiving electrons from a charged object in order to neutralize that object” (Grounding - the Removal of a Charge, 2016).
A ground ring provides a common ground for all electrical systems and offers a convenient place to bond multiple electrodes of a grounding system, encircling the building in a continuous ring.
The ground ring consists of a partially exposed wire, usually made of copper, with a conductor size of 2 AWG (American Wire Gauge), which is a heavy gauge wire. The larger the conductor, the more surface area is in contact with the earth and the lower the resistance to the earth.
Number 2 AWG wire is approximately 0.25 inches (6.54 mm) thick. The wire must be buried at least 2.5 feet (75 cm) underground and outside the dripline to help prevent corrosion. The ring ground must encircle the entire structure around which it is installed.
This device can be used for dissipating electricity from direct lighting strikes as a part of a lightning protection system.
Ground system for a radio transmitting antenna. (Photo courtesy of Philip E. Galasso, K2PG)
Risks Addressed:
Grounding of electrical systems is an important technique for reducing the risk of electric shock or damage due to lightning strikes. If electric insulation fails in some part of a system or electric device, the electric ground will allow current to be dissipated into the earth instead of electrifying the structure or the device itself.
The effects of electric current on the human body are shown in Table 1.
Table 1. Effects of electricity on human body
(Source: https://www.osha.gov/Publications/3075.html )
How Risks are Reduced:
A ground ring is an addition to the grounding system of a building. The purpose of a grounding system is to remove the excess charge of an electrical system by transferring this additional energy to the earth. This transfer will reduce the risk of electrical shock to any occupant of the building.
Additional Considerations:
At a construction site, mainly those with exposed structural building steel, it is important to ensure that there is only one grounding electrode system. All grounding media in or on a structure shall be interconnected to provide a common ground potential. This guarantees that a difference of potential will not happen, reducing the risks of electrical shock to the workers.
Note: The mentioned companies provide wires in appropriate lengths that can encircle the structures to be protected by the grounding system.
Contributors:
Availability
Hubbel Power Systems, Inc.
To obtain information, visit http://www.hubbellpowersystems.com
or contact 1-573-682-5521
Salisbury by Honeywell
To obtain information, visit http://www.salisburybyhoneywell.com
or contact 1-877-406-4501
