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FUNDAMENTAL GROUNDING PRACTICES

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Grounding Terminology

  • Bonded (Bonding)
  • Bonding Jumper
  • Bonding Jumper, Equipment
  • Bonding Jumper, Main
  • Ground
  • Grounded
  • Grounded, Effectively
  • Grounded Conductor
  • Grounding Conductor
  • Grounding Conductor, Equipment (EGC)
  • Grounding Electrode Conductor
  • Grounding Electrode
  • Ground-Fault Circuit Interrupter
  • Ground Fault Protection of Equipment
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Electrical Safety Standards

The most important piece of safety equipment is common sense. All other areas and practices of safety draw upon common sense. Prior to starting work, each worker should receive the safety rules and review and abide by them while on the assignment. A job supervisor should be designated for each assignment to provide work direction and safety coordination.

There are many hazards in the field that affect personnel on a daily basis. The nature of business implies that personnel, in order to perform their assigned task, must recognize and understand the hazards involved. Additionally, workers must know what actions are to be taken if an accident occurs.

National Electrical Safety Code

The National Electrical Safety Code (NESC) is a publication issued by the Institute of Electrical and Electronics Engineers (IEEE) that states the rules and guidelines considered necessary for the safety of personnel and equipment. These rules are applicable during the installation, operation, and maintenance of electrical equipment, from the generating facility to the customer's end usage. Operational procedures are designed to meet or exceed the requirements listed in the NESC. The NESC contains the purpose, requirements, and guidelines for the following major topics:

  • Electric equipment grounding
  • Installation and maintenance of electrical supply stations and equipment
  • Installation and maintenance of overhead/underground electrical lines
  • Operation of electrical lines and equipment

National Electrical Code

The National Electrical Code (NEC) is a publication of the National Fire Protection Association (NFPA), and its main purpose is the safeguarding of persons and property from the hazards associated with the use of electricity. It is to be used by qualified persons only. The ''Code'' covers installations of conductors and equipment inside and outside of both public and private buildings. The ''Code'' also defines what is not covered and the exceptions to the rules. The ''Code'' is not intended to be a design specification, as it may not be the most efficient or adequate to provide good service or provide adequacy for future electrical expansion.

Occupational Safety and Health Administration Electrical Standards

The Occupational Safety and Health Administration (OSHA) published this standard under authority of the ''Occupational Safety and Health Act'' of 1970. It is used by a variety of people in a variety of positions: the layman, worker, employer, compliance safety and health officer, union official, educator, and others. The intent of the standard is to provide a strict set of safety requirements designed to reduce the probability of industrial accidents and injuries.

Electrical safety requirements that are necessary for the practical safeguarding of employees in their workplaces are addressed in that sub-part of the following OSHA standards:

  • ''Safety Standards for Electrical Systems'' - Contains design safety regulations for all electric equipment and installations used to provide power and light to employee workplaces
  • ''Safety-Related Work Practices'' - Identifies the acceptable work practices of qualified and unqualified persons, the training requirements that pertain to each, the proper use of electrical equipment, and safeguards that pertain to the use of protective equipment

These instructions pertain to the operating requirements associated with construction, maintenance, and repair work on system electrical equipment. Compliance with these instructions is necessary for attaining the following objectives:

  • Safety of personnel
  • Continuity of service to customers
  • Prevention of damage to equipment

Proper ''grounding'' is of major concern for those who work on or around electrical equipment. It provides a safe path for electric current to flow in non-current-carrying conductive material. What does this mean if a current-carrying conductor contacts the housing, the conductive housing becomes energized, and a dangerous condition exists? This can cause severe injury, including death, should a person contact the housing and a grounded surface.

NEC Article 250 (latest revision) describes in detail the requirements necessary to ensure that electrical systems are grounded properly to ensure safety for everyone. In addition, local electrical codes need to be consulted to ensure compliance. These local codes are usually equal to, or more stringent, than the NEC.

IEEE Standard 142-2007

IEEE Recommended Practice for Grounding of Industrial and Commercial Power Systems is designed to assist the electrical engineer in making decisions on the subject of grounding power systems. It reviews the reasons for using or not using grounds and discusses the purpose for each.

Electrical Theory and Electrical Circuits

This section begins by defining the terms ''volt'', ''ampere'', and ''ohm''. Next, we discuss Ohm’s law and Kirchhoff’s laws. Simple and parallel electrical circuits are described, and types of electrical faults are discussed.

Basic Electrical Terms

Volt- The "volt" is the basic unit of electrical pressure that forces an electrical current to flow through an electrical circuit.

Ampere- The "ampere," or "amp" is the basic unit of electrical current flow; one milliamp (mA) is one-thousandth of an ampere.

Ohm- The "ohm" is the basic unit of resistance to the flow of electrical current; it is the resistance of a conductor across which there is a potential drop of one volt when a current of one amp flows through it. A constant driving voltage applied to an electrical circuit causes the amount of current flowing to decrease as the circuit resistance increases. The converse of the statement also is true; the symbol for resistance is either '''R''' or '''Ω'''.

Ohm's Law

Possibly, the most important electrical fundamental to understand is Ohm's law. It is a very simple statement of the relationship between voltage, current, and resistance in a DC circuit. The law states, "1 volt of electrical pressure will force 1 amp of current through a circuit having a resistance of 1 ohm." Ohm's law is shown by the following formula:

where:

=

I

current (amperes)

=

Effective coating resistance in ohms for one average square foot

Bare Pipe1

10,000

25,000

50,000

100,000

500,000

1,000,000

5,000,000

Perfect Coating

1Bare pipe assumed to require a minimum of 1 milliamp per square foot.