Electrical Safety Laboratory Curriculum for the Safety Sciences Undergraduate: Theory to
Application
By
Dr. Laura Helmrich Rhodes, CSP and David P. Rhodes, CSP
Abstract
Electrocution is the third leading cause of work-related deaths among 16 and 17 year-olds, after motor vehicle
deaths and workplace homicide. (1) The Occupational Safety and Health Administration (OSHA) reports that
approximately 350 electrical-related fatalities occur each year (2) Students enrolled in the Indiana University of
Pennsylvania (IUP) Department of Safety Sciences are required to take a course that prepares them to recognize and
evaluate electrical hazards, and assist in the implementation of hazard controls to prevent electrical fatalities and
injuries in the workplace. This article describes the lecture portion of the course and the three phases of the
laboratory training: power generation/ distribution tour and inspection, understanding basic wiring and using test
equipment to identify electrical hazards. As a part of this article, two sample laboratory activities are provided as
well as some ideas for implementing these activities at your institution.
Introduction
NIOSH reports that because electricity is a familiar part of our lives, it often is not treated with enough caution. As a
result, an average of one worker is electrocuted on the job every day of every year! Electrocution is the third
leading cause (12%) of work-related
deaths among 16- and 17-year-olds, after motor vehicle deaths and workplace homicide. (1) The Occupational
Safety and Health Administration (OSHA) reports that approximately 350 electrical-related fatalities occur each
year (2)
Students enrolled in the Indiana University of Pennsylvania (IUP) Safety Sciences SAFE 211, Principles of
Industrial Safety II, are provided with electrical safety training as part of the undergraduate curriculum. The
objective of the electrical safety training is to prepare students to recognize and evaluate hazards, and assist in the
implementation of hazard controls to prevent electrical fatalities and injuries in the workplace. This required course
is comprised of three (3) hours of lecture per week along with a three (3) hour laboratory for a total of four (4)
academic credits.
The department offers the Bachelor of Science degree in Safety Sciences with specialization in occupational safety
and health. The mission of the Safety Sciences Department is to prepare individuals for careers in the safety
sciences, which encompass occupational safety, occupational health, environmental safety, fire protection,
ergonomics, systems safety, emergency planning and response, and safety management. The Safety Sciences
Department has educated more than 1,900 safety and health professionals over the past thirty years with placement
rates consistently above 90%. These graduates have excelled in their careers and are employed in a variety of
industries, such as oil, chemicals, textiles, construction, steel, insurance, and manufacturing. The IUP Safety
Sciences Program is one of fewer than six (6) safety programs that is accredited by the Applied Science
Accreditation Commission of the Accreditation Board for Engineering and Technology (ABET). This is the
recognized accreditor for college and university programs in applied science, computing, engineering, and
technology and is a federation of thirty-one (31) professional and technical societies representing these fields.
There remains a need in Pennsylvania and the nation for university-educated occupational safety and health
professionals. The program in Safety Sciences prepares the student for professional, administrative, managerial, and
supervisory positions in industry, manufacturing, insurance, transportation, utility, government, construction, trade
service industries, and other sectors. The curriculum includes a major of 41 semester hours in Safety Sciences and
an additional 16 semester hours in related professional courses. A variety of elective courses are available in both
the major and professional fields that enable students to strengthen their primary interest areas.
The Safety Sciences course SAFE 211, Principles of Industrial Safety, is an undergraduate course which stresses an
understanding of the complexity of the industrial hazard control problem by thoroughly examining elements of
safety and health enumerated in the OSHA promulgated standards and various consensus standards. An emphasis is
placed on electrical safe work practices, personal protective equipment, welding and cutting, walking and working
surfaces, materials handling and storage, and construction safety. Students get the opportunity to apply hazard
control strategies in laboratory sessions.
Electrical Hazards: The Basic Fundamentals
The electrical section introduces the student to the basic principles of electricity. Topics include electrical
fundamentals, ampacity and Ohm's Law, and the effects of electricity on the human body. Students also learn how
electrical shocks occur in the workplace. Electricity travels in closed circuits, normally
through a conductor. The Occupational Safety and Health Administration
(OSHA) reports that shock results when the body becomes part of the
electrical circuit; current enters the body at one point and leaves at another.
Typically, shock occurs when a person contacts:
Both wires of an energized circuit
One wire of an energized circuit and the ground
A metallic part in contact with an energized wire while the person is also in contact with the ground
“Metallic parts of electric tools and machines can become energized if there
is a break in the insulation of their wiring. A low-resistance wire between the
metallic case of the tool/machine and the ground – an equipment grounding
conductor – provides a path for the unwanted current to pass directly to the
ground. This greatly reduces the amount of current passing through the
body of the person in contact with the tool or machine. Properly installed,
the grounding conductor provides protection from electric shock”
(http://www.osha.gov/SLTC/etools/construction/electrical_incidents/howshocksoccur.html#) (3)
Electrical hazard recognition, OSHA’s electrical standards, electrical branch circuit and equipment inspection
procedures, and training in various types of electrical test equipment are also covered in the course. In addition,
students under the Safety Sciences curriculum are required to take two (2) semesters of Physics in order to learn the
theories and principles of electricity and magnetism. SAFE 211 reinforces the Physics theories while allowing future
practitioners to apply recognition, evaluation, and control skills.
Perhaps, the value of the establishment of electrical standards is best summarized by the National Fire Protection
Association’s National Electrical Code Handbook. (4) “Workmen frequently created standards as they worked and
rarely did two men think alike.” (NFPA, NEC Handbook 1996, pp xiii) All lab activities stress students becoming
familiar with the OSHA’s electrical standards including those pertaining to General Industry including 29 CFR
1910.137, Electrical protective devices, 1910.269, Electric Power Generation, Transmission, and Distribution and
29 CFR 1910 Subpart S-design safety standards for electrical systems and Safety-related work practices. Also,
OSHA’s electrical-related construction standards including 29 CFR 1926 Subpart K are included.
Electrical Safe Work Practices: The Regs
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In the lecture, prior to the laboratory, students are provided with training in electrical safety-related work practices
and procedures. OSHA general industry and construction standards require that employees who face a risk of
electric shock that is not reduced to a safe level by the electrical installation or may reasonably be expected to face
comparable risk of injury due to electric shock or other electrical hazards be provided training in electrical safetyrelated work practices and procedures. The OSHA electrical safety-related standards outline the training, selection
and use of work practices, safe use of electrical equipment and safeguards for personal protection that must be
followed by an employer as part of an overall effective safety and health program. In addition, students are provided
instruction in the National Fire Protection Association (NFPA) standard 70 E - Electrical Safe Requirements for
Employee Workplaces. This standard addresses those electrical safety requirements for employee workplaces that
are necessary for the practical safeguarding of employees in the pursuit of gainful employment. These electrical
safety rules and practices are written into the course module instructions and reviewed extensively and repeatedly
during the laboratory exercises
Students are instructed to use the NIOSH three-stage safety model: recognize, evaluate,
and control electrical hazards. The lab reinforces the idea that professionals
need to use this model when assessing work; to be considered safe while
working on or near energized systems, one must think about the job and
plan for hazards. To avoid injury or death, one must understand and
recognize hazards. A person needs to evaluate the situation they are in and
assess their risks. Furthermore there is a need to control hazards by creating
a safe work environment, by using safe work practices, and by reporting
hazards (NIOSH Publication , Electrical Safety -Safety and Health for Electrical Trades Student Manual,
January 2002, Publication No. 2002-123, Section 4 page 1) (5)
The electrical module of the course content is a three-step instructional process starting with a field trip to an
electrical generating station, wiring an electrical circuit in the laboratory and using electrical test instruments to
evaluate the electrical circuits developed in the laboratory. Students follow an instructor created simple inspection
checklist published in the Lab Manual. The check list is based, in part, on NFPA 70. (Laboratory Exercise Co- Gen
Inspection Checklist) Items noted will be summarized in a laboratory report compiled by each student. The
following discussion breaks down these phases of instruction as well as some of the sub-set specifics of the lessons.
Phase I: Power Generation and Distribution Facility Tour and Inspection
The first module is a field trip to the S.W. Jack Cogeneration Facility located at IUP.
This cogeneration facility produces electricity, steam, and hot water by using natural
gas-powered engines. The plant utilizes dual-fuel four cycle reciprocating engines to
produce electricity and heat. During the operation of the engines, electricity is generated
and engine exhaust is directed to the high pressure waste heat (firetube–type) boilers
where steam is generated. In addition, pressure vessels are used to store air and water
under pressure . (Insert Diagram from Cogen)
The field trip to the co-generation facility allows the students to see how electricity
works. OSHA’s uses the analogy that operating an electrical switch is like turning on a
water faucet. Behind the faucet (or switch) there is a source of water (or electricity), a
way to transport it, and pressure to make it flow. The faucet's water source is a reservoir
or pumping station. A pump provides enough pressure for the water to travel through
the pipes. The switch's electrical source is a power generating station. A generator
provides the pressure for the electrical current to travel through electrical conductors, or
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wires.
(http://www.osha.gov/SLTC/etools/construction/electrical_incidents/elecworks.html) (6)
The objective of this field trip is to offer students the opportunity to learn how electricity
is generated; the potential hazards in this environment, and their controls. Students are
provided instruction in the operation of electrical generators and pressure vessel at the
cogeneration plant. Students perform evaluations of electrical systems and pressure
vessel system components at the cogeneration facility.
Transformers: Stepping up and stepping down
Students learn the operation of electrical system components including transformers, electrical distribution panels
and electrical receptacles and are instructed on how to perform a hazard control evaluation of the equipment. A
transformer increases or decreases the voltage in an electrical system. Transformers are used first to increase the
energy to a high voltage for conduction over many miles of transmission wires, and then to decrease this voltage to
values which are convenient and safe for use by the consumer. (Alerich, W.M., & Keljik, Electricity-Power
Generation and Delivery, Delmar Publishers, Albany, N.Y.Sixth Edition, page 114)(7)
Transformers that use oil as an insulator are subject to fires because the combustible nature of oil and the heatgenerated nature of electrical equipment. (An Illustrated Guide to Electrical Safety, ASSE, page 87) (8) Oil filled
transformers should be evaluated to determine Polychlorinated Biphenyls (PCBs) content. The Environmental
Protection Agency (EPA) http://www.epa.gov/opptintr/pcb/) (9) reports that PCBs have been demonstrated to cause
a variety of serious health effects. Due to their non-flammability, chemical stability, high boiling point and electrical
insulating properties, PCBs were used in hundreds of industrial and commercial applications including electrical
equipment PCBs have been shown to cause cancer and a number of serious non-cancer health effects in animals,
including effects on the immune system, reproductive system, nervous system, and endocrine system. More than 1.5
billion pounds of PCBs were manufactured in the United States prior to cessation of production in 1977. Concern
over the toxicity and persistence in the environment of Polychlorinated Biphenyls (PCBs) led Congress in 1976 to
enact §6(e) of the Toxic Substances Control Act (TSCA) that included among other things, prohibitions on the
manufacture, processing, and distribution in commerce of PCBs. Thus, TSCA legislated true "cradle to grave" (i.e.,
from manufacture to disposal) management of PCBs in the United States. The EPA mandates the action that a
transformer owner must take if the oil-filled transformer contains PCB’s.
Power Lines: Getting Electricity From Here to There
The hazards of overhead power lines are reviewed with the students.
Overhead power lines are un-insulated and can carry tens of thousands of
volts, making them extremely dangerous to employees who work in their
vicinity. Fatal electrocution is the main risk, but burns and falls from
elevation are also hazards. Using tools and equipment that can contact
power lines increases the risk. More than half of all electrocutions are caused
by direct worker contact with energized power lines. Power line workers
must be especially aware of the dangers of overhead lines. In the past, 80%
of all lineman deaths were caused by contacting a live wire with a bare hand.
Due to such incidents, all linemen now wear special rubber gloves that
protect them up to 34,500 volts. Today, most electrocutions involving
overhead power lines are caused by failure to maintain proper work
distances. ( NIOSH Publication , Electrical Safety -Safety and Health for Electrical Trades Student Manual,
January 2002, Publication No. 2002-123, Section 5 page 3) (10)
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.
OSHA (Controlling Electrical Hazards. OSHA publication, 2002, Washington, DC) (11) reports that most electrical
accidents result from one of the following
three factors:
• unsafe equipment or installation,
• unsafe environment, or
• unsafe work practices.
Students are instructed in the ways to prevent these accidents: through the use of insulation, guarding, grounding,
electrical protective devices, and safe work practices. Students perform a series of inspections and evaluations of
plant equipment, and observe work employee practices during the visit to ensure that potential electrical hazards are
controlled at this worksite.
Electric Motors & Switchgear
Students are provided with instruction on the types of inspection and testing activities that should be performed on
electrical motors and miscellaneous electrical apparatus including switchgear during the Co-generation Plant visit.
Electrical equipment is visually inspected to assure the presence of guards. Guarding involves locating or enclosing
electric equipment to make sure people don’t accidentally come into contact with its live parts. Per OSHA standards,
effective guarding requires equipment with exposed parts operating at 50 volts or more to be placed where it is
accessible only to authorized people qualified to work with it. Recommended locations are a room, vault, or similar
enclosure; a balcony, gallery, or elevated platform; or a site elevated 8 feet (2.44 meters) or more above the floor.
Sturdy, permanent screens also can serve as effective guards. Conspicuous signs must be posted at the entrances to
electrical rooms and similarly guarded locations to alert people to the electrical hazard and to forbid entry to
unauthorized people. Signs may contain the word “Danger,” “Warning,” or “Caution,” and beneath that, appropriate
concise wording that alerts people to the hazard or gives an instruction, such as “Danger/High Voltage/Keep Out.”
(Controlling Electrical Hazards. OSHA publication, 2002, Washington, DC)(11)
Testing Receptacles
Students use electrical test equipment to evaluate plant equipment and components for a proper electrical ground.
“Grounding” a tool or electrical system means intentionally creating a low-resistance path that connects to the earth.
This prevents the buildup of voltages that could cause an electrical accident. Grounding is normally a secondary
protective measure to protect against electric shock. It does not guarantee that you won’t get a shock or be injured or
killed by an electrical current. It will, however, substantially reduce the risk, especially when used in combination
with other safety measures .A service or system ground is designed primarily to protect machines, tools, and
insulation against damage. One wire, called the “neutral” or “grounded” conductor, is grounded. In an ordinary lowvoltage circuit, the white or gray wire is grounded at the generator or transformer and at the building’s service
entrance. An equipment ground helps protect the equipment operator. It furnishes a second path for the current to
pass through from the tool or machine to the ground. This additional ground safeguards the operator if a malfunction
causes the tool’s metal frame to become energized. The resulting flow of current may activate the circuit protection
devices. (Controlling Electrical Hazards. OSHA publication, 2002, Washington, DC)(11)
Checking Records
Students are instructed in the importance of periodic inspections and maintenance of electrical systems. Students
have the opportunity to review maintenance and inspection logs at the power plant and compare those practices to
promulgated standards. Periodic inspections should be conducted for all electrical system equipment and
components in order to identify all electrical hazards present. Records should be kept of any electrical hazards
identified, and appropriate corrective action should be taken immediately. These periodic inspections should be
supplemented with daily inspections by the personnel using this equipment. (Preventing Electrocutions Due to
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Damaged Receptacles and Connectors NIOSH ALERT: October 1986, DHHS (NIOSH), Publication No. 87-100)
(12)
Students are instructed that electrocution is not the only hazard faced by employees working in the electrical field.
Between 1999 and 2002, more than 30 percent of all workers' compensation claims from the Independent Electrical
Contractors (IEC) were related to ergonomics. This amounted to more than $10 million in claims in just four years.
OSHA has developed an *eTool which describes common hazards including heavy lifting; pushing, pulling; &
carrying; staging & housekeeping and vehicular hazards that electrical contractors may encounter and possible
solutions for these hazards. http://www.osha.gov/SLTC/etools/electricalcontractors/index.html (13)
Fired & Unfired Pressure Vessels
The evaluations of pressure vessel systems by students includes learning how to
perform in-service inspections of fire tube boilers and air receivers using the American
Society of Mechanical Engineers (ASME) National Board Boiler and Pressure
Inspection Code as a point of reference (www.nationalboard.org). The Boiler and
Pressure Vessel Code defines minimum "good practice" requirements needed to assure
sound boiler design and operation. It covers qualification of fabricating shops, design,
materials specifications, and testing and inspection procedures. In many states use of
the code is a legal requirement. The code has been widely applied, and failures from
design deficiencies in boilers and pressure vessels have become a rare occurrence.
(14) Definitions of a boiler and a pressure vessel are shown below.
Definitions
Boiler: a closed pressure vessel in which a fluid is heated for use
external to itself by the direct application of heat resulting from the
combustion of fuel (solid, liquid, or gaseous) or by the use of electricity
or nuclear energy. This can use steam, hot water, or other working
substances) (15)
Pressure Vessels: range from storage tanks in which a gas or liquid is
stored under pressure to large chemical reactor vessel where with
pressure, and perhaps temperature, chemical change takes place
among the fluids or gases stored under pressure in the vessel system. A
simple classification includes storage vessels, rotating pressure vessels,
heat exchangers, cookers, and chemical reactors(16):
The National Board of Boiler and Pressure Vessel Inspectors was created in 1919 to promote greater safety to life
and property through uniformity in the construction, installation, repair, maintenance and inspection of boilers and
pressure vessels. The National Board membership oversees adherence to codes involving the construction and repair
of boilers and pressure vessels.
Students meet with the plant’s operator to discuss the operation of a boiler. Students perform an in-service
inspection of a fire tube boiler, which starts with determining the maximum allowable working pressure (MAWP).
Students take readings (recorded on inspection checklist) of the pressure gauge to determine the operating pressure
and to determine if the boiler is operating within the allowable working pressure. Students also take readings of the
water sight glass to determine if the boiler water level is satisfactory. The instructors use the analogy of a tea-kettle
to describe the operation of a boiler and the importance of the water level. Water is placed in the tea-kettle and if left
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unattended, the water can change to steam, boiling out all the water, but the burner is still on and can cause a fire
resulting in bodily injury and property damage. A low water condition can severely impair the structural members of
a boiler. To prevent serious damage that may occur as a result of low water the boiler should be equipped with a
low-water cutoff which immediately shuts down the boiler if the water drops to a dangerously low level. (Elonka,
S.M., Kohan, A. L., Standard Heating and Power Boiler Plant Questions & Answers, 1984, McGraw-Hill Books,
New York, N.Y., page 376)
In addition to the waste heat boilers, the cogeneration plant is equipped with auxiliary
boilers to provide additional steam for heat and hot water in the winter months. Students
are provided instruction in the operation of the boiler furnace combustion controls to
prevent leakage and accumulation of gaseous fuel in the furnace. National Fire
Protection Association (NFPA) 85, Standard for the Prevention of Furnace Explosions
in Fuel Oil- and Natural Gas-Fired Single Burner Boiler- Furnace reviews the
recommended equipment and practices to prevent gas fuel explosions.
Safety Valves: Up Close and Personal
Power plant operations staff provides the class with new pressure relief valves for
students to handle. The instructor then reviews the purpose and operation of the boiler
safety relief valves. An inspection of the boiler safety relief valve is performed by
students to assure that the manufacturer of the safety valve holds the required National
Board stamp and that it is set at the proper pressure and relief capacity settings. Data is
then recorded in the Lab Manual Checklist.
A review of the boiler operation and maintenance logs is performed to understand the
daily checks performed by the operator including the importance of proper water
treatment. The most common cause of overheating and failure of boiler tubes is the
formation of hard scale on the boiler tube surfaces. This is caused by calcium and
magnesium in the boiler water. When untreated, boiler water is heated and the calcium
and magnesium will precipitate from the solution to form hard scale on the tube
surfaces. (17)
The next exercise is for the students to evaluate an air receiver which is a pressure vessel used to store compressed
air. OSHA reports that recent inspections of pressure vessels have shown that
there are a considerable number of cracked and damaged vessels in
workplaces. Cracked and damaged vessels can result in leakage or rupture
failures. Potential health and safety hazards of leaking vessels include
poisonings, suffocations, fires, and explosion hazards. Rupture failures can
be much more catastrophic and can cause considerable damage to life and
property. The safe design, installation, operation, and maintenance of
pressure vessels in accordance with the appropriate codes and standards are
essential to worker safety and health.
Once again, students use the National Board Inspection Code as a point of reference to perform an in-service
inspection of the air receiver. Students review the National Board of Boiler and Pressure Vessel Inspectors Recommendations for a Safe Boiler Room shown below. (Laboratory Activity- In Service Air Receiver. (18) Data
that is recorded throughout the lab is later used to write a lab summary which requires the synthesizing of data and
the formulation of meaningful recommendations for hazard control.
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Laboratory Activity
In-service Inspection of the Air Receiver
Directions: Use the following questions to evaluate the boiler room safety.
Source: National Board of Boilers and Pressure Vessel Inspectors Recommendations for a Safe Boiler Room
Condition
Boiler room clean and clear of all unnecessary items. The boiler room
should not be considered an all-purpose storage area. The burner requires
proper air circulation in order to prevent incomplete fuel combustion and
the production of carbon monoxide.
Yes
No
Comments
All personnel who operate or maintain the boiler room are properly trained
on all equipment, controls, safety devices, and up-to-date operating
procedures.
Boiler room is free of all potentially dangerous situations, like flammable
materials and mechanical or physical damage to the boiler or related
equipment. Clear intakes and exhaust vents; check for deterioration and
possible leaks.
Thorough inspection by a properly qualified inspection, such as one who
holds a National Board commission. (Up to date certificate?)
After any extensive repair or new installation of equipment, make sure a
qualified boiler inspector re-inspects the entire system.
Monitor all new equipment closely until safety and efficiency are
demonstrated.
Boiler operating log sheets, maintenance records, on hand. Manufacturer's
recommendations used to establish a preventive maintenance schedule
based on operating conditions, past maintenance, repair, and replacement
that were performed on the equipment.
Checklist for proper startup and shutdown of boilers and all related
equipment according to manufacturer's recommendations.
Observe equipment extensively before allowing an automated operation
system to be used with minimal supervision.
The Power Plant: An Introduction to Permit Required Confined Space
The Cogeneration Plant contains spaces including boilers and pressure
vessels that are considered "confined" because their configurations hinder
the activities of any employees who must enter, work in, and exit them. For
example, employees who inspect and repair boilers and pressure vessels
generally must squeeze in and out through narrow openings and perform
their tasks while cramped or contorted. OSHA uses the term "confined
space" to describe such spaces. In addition, there are many instances where
employees who work in confined spaces face increased risk of exposure to
serious hazards. In some cases, confinement itself poses entrapment
hazards. In other cases, confined space work keeps employees closer to
hazards, such as asphyxiating atmospheres or the moving parts of
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machinery. OSHA uses the term "permit-required confined space" (permit
space) to describe those spaces that both meet the definition of "confined
space" and pose health or safety hazards. OSHA has developed a Confined Spaces Advisor
1.1. OSHA (1997, December) available at their webiste (www.osha.gov). This is interactive expert help for the
Permit-Required Confined Spaces Standard (29 CFR 1910.146). It will assist users to identify confined spaces and
deal with permit-required confined spaces
Within Safety Sciences, students are taught that physical hazards and unsafe behaviors observed are tied back to
deficiencies in the overall safety and health program. The OSHA Elements of an Effective Safety and Health
Program. 1989 Voluntary Safety and Health Program Management Guidelines (19) are referenced extensively in the
laboratory exercises. OSHA has concluded that effective management of worker safety and health protection is a
decisive factor in reducing the extent and the severity of work-related injuries and illnesses. Effective management
addresses all work-related hazards, including those potential hazards that could result from a change in worksite
conditions or practices. It addresses hazards whether or not they are regulated by government standards. Student use
this “school of thought” when synthesizing data and recommendations are developed.
Phase II: Understanding Basic Wiring
The second phase of the laboratory is the wiring of 120v single-phase receptacles and basic lighting circuits by the
students in the safety laboratory. Students construct a “mock-up” of a branch circuit with receptacles, and lights
controlled by switches. Students also learn electrical wiring terminology and how to identify deficiencies. The
OSHA electrical standards are used as a point of reference to evaluate their electrical wiring arrangement.
The following hazards are the most frequent cause of electrical injuries (OSHA
http://www.osha.gov/SLTC/etools/construction/electrical_incidents/mainpage.html).
Students learn how to recognize these electrical system deficiencies and possible solutions:
Lack of Ground-Fault Protection
Path to Ground Missing or Discontinuous
Equipment Not Used in a Manner Prescribed
Improper Use of Extension and Flexible Cords
Normal use of electrical equipment at a workplace causes wear and tear that may result in
insulation breaks, short-circuits, and exposed wires. If there is no ground-fault protection, these
can cause a ground-fault that sends current through the worker's body, resulting in electrical
burns, explosions, fire, or death.
Wiring Receptacles & GFCI
Students wire receptacles in branch circuits that are protected by a ground fault circuit interrupter (GFCI) to avoid
the danger of ground-fault hazards. GFCIs can be used successfully to reduce electrical hazards at general industry
and construction sites. The ground-fault circuit interrupter (GFCI) is a fast-acting circuit breaker which senses small
imbalances in the circuit caused by current leakage to ground and, in a fraction of a second, shuts off the electricity.
The GFCI continually matches the amount of current going to an electrical device against the amount of current
returning from the device along the electrical path. Whenever the amount "going" differs from the amount
"returning" by approximately 5 milliamps, the GFCI interrupts the electric power within as little as 1/40 of a second.
(OSHA, Ground-Fault Protection on Construction Sites, Construction Safety and Outreach Program, U.S.
Department of Labor, OSHA Offices of Training and Education, May 1996) (20)
Students learn that if the power supply to the electrical equipment at the
worksite is not grounded or if the path has been broken, fault current may
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travel through a worker's body, causing electrical burns or death. Even when
the power system is properly grounded, electrical equipment can instantly
change from safe to hazardous because of extreme conditions and rough
treatment. For example, removing the ground pin from a plug to fit an ungrounded outlet not only means your
work area is unsafe, but makes the cord unfit for future work where there is grounding.
If electrical equipment is used in ways for which it is not designed, you can
no longer depend on safety features built in by the manufacturer. This may
damage your equipment and cause employee injuries For example, using circuit
breakers or fuses with the wrong rating for over-current protection, e.g. using a 30-amp breaker in a system with 15or 20-amp receptacles. Protection is lost because the breaker will not trip when the system's load has been exceeded.
With the wide use of power tools at worksites, flexible extension cords often
are necessary. Students explore the use and potential hazards associated with extension cords. The
normal wear and tear on extension and flexible cords at a worksite can
loosen or expose wires, creating hazardous conditions. For example, cords
that are not 3-wire type, not designed for hard-usage, or that have been
modified, increase your risk of contacting electrical current.
Phase III: Testing Wiring with Common Test Equipment
The final phase of the laboratory is the use of electrical test equipment by the students to assist in the identification
of electrical system deficiencies (hazards). A circuit analyzer is used by students to evaluate the safety of the branch
circuit that they wired in the laboratory for proper current capacity, proper wiring and the quality and overall
suitability of the circuit to support electric loads. In addition, the circuit analyzer is used to identify hazardous
conditions, loose connections, shared neutrals, false grounds, and grounding quality. A continuity test is performed
to ensure that the equipment grounding conductor is electrically continuous. A terminal connection test is performed
to ensure that the equipment grounding conductor is connected to its proper terminal. By, far this is the most
enlightening activity. Students have just built a receptacle and a GFCI receptacle following schematics, step-by-step.
Some teams find they have an error when they use the test equipment. The real learning takes place when they take
the face plate off and see what exactly is meant by an open neutral or reversed polarity!
Infrared scanning is used for predictive maintenance and helps determine whether or not equipment and machinery
are operating safely and at optimum capacity. Students use a hand-held, non-contact, infrared thermometer device
with a laser pointer to detect problems including overloaded circuitry and loose electrical connections. The infrared
thermometer device is an excellent tool for the safety and health professional to use to measure surface temperature
of objects which are difficult to reach or unsafe to contact and measure hot spots in electrical panels and equipment.
These tests are conducted on their own, team built, display boards. The materials and test equipment are purchased
through student fees and support from various foundations. The boards are dismantled and materials stored from
semester to semester in the lab facility.
Evaluation and feed back of the electrical laboratory exercises by the students and alumni indicate that they found it
to be a rewarding learning experience. Many of the students indicated that they had limited experience with
electricity, and some expressed a “fear” of learning the subject prior to the laboratory. Perhaps most rewarding, is
that most students report a better understanding of the theories presented in Physics II (electricity) and their
application to safety sciences.
In order for students to be successful as safety and health practioners they need a command of electricity which
requires both the academic science training, and the “hands-on” wiring experience. Mistakes are common in the
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laboratory environment but learning how to recognize, evaluate and correct the adverse conditions in this
environment will prepare the students to save lives and properties in the future.
Summary
The objective of electrical safety with in Safety Sciences is to prepare students to recognize and evaluate hazards,
and assist in the implementation of hazard controls to prevent electrical fatalities and injuries in the workplace.
Years ago, when studying to be a safety professional, our course work only included labs in industrial hygiene and
systems safety. So much of safety lends itself to hands-on instruction and electricity is a great example. The
combination of a power generation and distribution plant tour, using inspection checklists, and receptacle wiring
activities followed by the use of tools often used by safety practitioners, allows students to synthesize electrical
theory into practical application. When professional safety education was in its infancy electrical test equipment was
shown to students but not how to use it or what it meant if a hazard was identified. Now, academically prepared
safety professionals can get the theory and experiment with being a working safety professional. The result is they
have a better understanding of what the instruments indicate, how to discuss those hazards with engineers and
electricians so that appropriate controls can be implemented and perhaps most important is an increased confidence
level.
How Other Academics Can Use This Information
Safety educators should consider implementing the following into the courses which address electrical hazards:
•
Contact a local power generation facility to arrange a tour. If you don’t have one locally, consider
visiting a manufacturing facility that produces a portion of their power for their process.
•
To boost your own confidence in the area of electrical hazards and controls, contact a local
vocational school and consider enrolling in a residential wiring course yourself. Also, obtain the
OSHA electrical safety trainer authorization.
•
Obtain wiring components, through student fees and foundations. Have students wire a basic
receptacle on a display board, power it up and then test it to see if it’s done correctly. Consider
having them wire a GFCI and even a three-way switch. An alternative to this is to create a test
board that has receptacles that are already incorrectly wired. Then have students test the board
and complete a worksheet indicating the hazards.
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REFERENCES
1. NIOSH Publication, Electrical Safety -Safety and Health for Electrical Trades
Student Manual, January 2002, Publication No. 2002-123, page 1
2. OSHA Construction eTool, www.osha.gov, Washington, DC, 11/02/2004
3. OSHA Construction Fatalities: How Electricity Works
(http://www.osha.gov/SLTC/etools/construction/electrical_incidents/howshocksoccur.html#) 11/02/2004
4. National Fire Protection Association, National Electrical Code Handbook.
5. NIOSH, Electrical Safety -Safety and Health for Electrical Trades Student Manual, January 2002, Publication No.
2002-123, Section 4 page 1
6. http://www.osha.gov/SLTC/etools/construction/electrical_incidents/elecworks.html)
11/02/2004
7. Alerich, W.M., & Keljik, Electricity-Power Generation and Delivery, Delmar Publishers, Albany, N.Y.Sixth
Edition, page 114
8. ASSE , An Illustrated Guide to Electrical Safety, page 87
9. Environmental Protection Agency, http://www.epa.gov/opptintr/pcb/ 11/02/2004
10. NIOSH , Electrical Safety -Safety and Health for Electrical Trades Student Manual, January 2002, Publication
No. 2002-123, Section 5 page 3
11. Controlling Electrical Hazards. OSHA publication, 2002, Washington, DC
12. Preventing Electrocutions Due to Damaged Receptacles and Connectors NIOSH ALERT: October 1986, DHHS
(NIOSH), Publication No. 87-100
13. http://www.osha.gov/SLTC/etools/electricalcontractors/index.html (11/8/2004
14. A.S. Krisher ,Plant Integrity Programs, Classic Series, January 1998, National Board Bulletin, Columbus OH.
15. Elonka. S.M., Kohan, A. L. , Standard Heating and Power Boiler Plant Questions & Answers, 1984, McGrawHill Books, New York, N.Y., page 25
16.Kohan, A. L. Pressure Vessel Systems, 1987 McGraw-Hill Books, New York, N.Y., page 33.
17. Lee Doran Water Maintenance Essential to Prevent Boiler Scaling, Summer 1996 National Board BULLETIN.,
Columbus, OH
18. National Board Classic Series, 2002, The National Board of Boiler and Pressure Vessel Inspectors, Columbus,
OH
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19. OSHA Elements of an Effective Safety and Health Program. 1989 Voluntary Safety and Health Program
Management Guidelines
20. OSHA, Ground-Fault Protection on Construction Sites, Construction Safety and Outreach Program, U.S.
Department of Labor, OSHA Offices of Training and Education, May 1996
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