GFCI Testers
The Ground Fault Circuit Interrupter tester is useful to determine if an
outlet has GFCI protection, sort of. Well, depending on the calibration of the
tester, it will be useful.
This one tester which should be replaced immediately when ever there is
evidence of damage. Also, it should be replaced every year. The old tester
should be discarded after being destroyed.
The problem with this tester is operator error. Be sure to read the
directions which come with the unit. All the directions. Also be prepared for
unusual results. Electricity is a funny acting energy at times.
There are many manufacturers of this tester. Click HERE
for a Google list of the manufacturers.
More about GFCI circuit testing from this excellent SOURCE.
Electricity has been around since the beginning of time in the forms of
lightning and static electricity. In 600 BC in Greece, it was observed that
amber rubbed with wool would attract light objects such as straw, feathers, and
bits of wood. Around 1570, William Gilbert, the man who is credited with coining
the word "electricity," discovered electrical properties in items
other than amber. The electric light bulb was invented in 1802, and Thomas
Edison was the first person to successfully market an incandescent lamp, in
1879.
With the ever-expanding use of electricity, the need was recognized for a
national standard to regulate electrical installations nationwide. The National
Electrical Code came into being in 1897. Through the National Fire Protection
Association it became NFPA 70 and remains the same today. It is the electrical
standard for the United States and other foreign countries, including Mexico.
The code is not a training manual; rather, it is a uniform standard used by
inspection agencies, designers, insurance companies, and others who are
responsible for electrical installations. The code is a minimum requirement for
safe installations, and parts of the code became Subpart S and Subpart K of
OSHA's standards.
Grounding
When electricity became part of our lives, whether in the workplace or at
home, effective grounding became our means of protection. Grounding is still a
required method of protection from shock in the event of an electrical fault.
This is the separate wire that is run with the circuit conductors and connected
to the non-current-carrying metal parts of equipment that could become energized
because of a fault.
A grounding conductor is also required in cords that are connected to tools,
equipment, and appliances. The only exception is if the tool is supplied through
an isolation transformer with an ungrounded secondary of not over 50 volts or
uses a system of approved double insulation. The grounding conductor gives a
direct path back to the grounding electrode (ground rod, structural steel, etc.)
if a fault occurs.
When the transistor was invented, we entered into a new era. Now, we were
faced with items such as transistor radios, which operated on batteries or
regular household current. In the mid to late 1960s, one could hardly read a
newspaper or watch the evening news without reading or hearing about a kid or
kids being electrocuted. Typically they would be sitting in the bathtub when
their radio (plugged into household current) fell into the tub, and
electrocuting them.
Hairstyles were changing during this period, and the hand-held hair dryer
became a part of practically every household. They posed a problem because they
were primarily used in the bathroom, near the lavatory. This presented
additional hazards because the water piping system was grounded, and a fault in
the hair dryer along with someone coming in contact with the faucets could
result in serious electrical shock or electrocution.
These factors led to introduction of Ground Fault Circuit Interrupters.
Understanding GFCIs
One of the items covered in the National Electrical Code is Ground Fault
Circuit Interrupters, or GFCIs. The GFCI is probably the most significant
life-saving device ever invented for protection against serious injury or death
caused by an electrical shock.
The GFCI is designed for "personal" protection, not to protect
equipment or the conductors of a circuit. While grounding is required and a
vital part of safety of both people and equipment, the grounding conductor
has nothing to do with the operation of GFCIs.
The GFCI senses an imbalance of current between the "hot" and
"neutral conductor." The GFCI really does not care about the current
draw (amps) passing through, as long as it is within the designed limits of the
device. Rather, it is monitoring the current difference in milliamperes between
the hot and neutral. A milliamp is .001 or 1/1000th of an ampere. If
this difference is at 5 milliamperes, plus or minus 1 milliampere, the device
"trips out," breaking the circuit.
A handheld hair dryer that is rated at 1,400 watts, 120 volts, will have a
current draw of approximately 11.6 amperes, or 11,600 milliamperes. An
industrial 3/8-inch electric drill will have a current draw of between 4 and 6
amperes, or 4,000 to 6,000 milliamps.
While electricity performs many tasks for us and makes our lives more
enjoyable, it is basically lazy. The lazy part is that it will seek the path of
least resistance to a grounding source. The resistance in a copper wire used as
the grounding conductor is very low and will allow current to flow rather
freely. In the event of an electrical fault in equipment that has a grounding
conductor, the current will flow to ground on the conductor.
Effects of Electricity
body has about 500 Ohms of resistance. If a person's body were to
become the path to ground, the body would become a high impedance ground path.
There is not enough current flowing through the body to trip an overcurrent
device (a fuse or circuit breaker; the GFCI is not an overcurrent device.)
In order for an overcurrent device to trip, the current draw (amps) must
exceed the rating of the device. For example, a circuit breaker rated at 20
amperes will not trip open until the current exceeds the 20 amperes. Using Ohm's
Law, on a 120 volt circuit with 500 Ohms of resistance, the current level would
be 240 milliamperes, or about 1/4th of an ampere. Even though this
seems like a small about of current, it is quite deadly when passing through the
body.
Shock in the range of 6 to 30 milliamps can be very painful, and the person
in contact cannot let go of the circuit. At around 50 milliamps respiratory
arrest is possible, with severe muscular contractions. Ventricular fibrillation
starts around 67 milliamperes of current. This is when the heart basically
starts fluttering and is not pumping blood through the system. If not
stabilized, death is a real possibility.
So you can see that if the GFCI is functioning properly, the current level
will never reach the danger point--because it trips at 5 milliamperes.
Testing GFCIs
UL 1943 is the standard for testing GFCIs. Each manufacturer must insure
that its product meets this standard. Included in the listing and labeling for
GFCIs are instructions that they be tested monthly.
Both the National Electrical Code and OSHA's electrical standards require
that equipment shall be used and installed in accordance with any instruction
included in the listing and labeling. The purpose of this is to ensure as much
as possible that the device is functioning properly.
The test is a very simple procedure where one can press the test button on
the device to ensure that it does trip, breaking the circuit. This test button
creates a difference of 5 milliamperes between the hot and neutral through a
resister built in the device. There are GFCI testers in the marketplace where
you can test the polarity of a receptacle and also trip the GFCI. I have stated
that the grounding conductor has no part to play in the operation of the GFCI, but
using the external tester the grounding conductor must be present because the
tester is using the hot and grounding conductor to trip the device.
Are Your GFCIs Working?
We take for granted that our GFCIs are providing protection if we can
operate a tool, hair dryer, or other item through them. Yet this is not always
the case. While the device will allow current to flow through it, the monitoring
of the current may not be taking place.
Built into the device is a metal oxide varistor (MOV) used as a surge
suppressor. The MOV absorbs the voltage surge and converts it into heat.
Repeated surges can degrade the MOV, still allowing current to flow but not
providing the protection required. Voltage surges such as lightning strikes in
the area can cause a surge, as can utility company switching. In the event a
GFCI trips out, is reset, and power is restored, you should go a step further
and press the test button to insure that the device trips open to stop the
current flow. If the device will not trip open, or if it trips and current
continues to flow, the device is defective and must be replaced.
Some parts of the country are more susceptible to lightning strikes than
others. This is a primary cause of GFCI failures. The International Association
of Electrical Inspectors obtained information from the American Society of Home
Inspectors about its findings in inspecting residences. This survey only covered
parts of the United States, and some of the figures are staggering about the
number of GFCIs that do not operate properly.
In parts of Florida, up to 58 percent of the GFCI circuit breakers were
defective, and 33 percent of the receptacles. Of the states from which
information was obtained, Washington state had least number of failures. The
survey covered parts of New York, Florida, Texas, California, Washington, and
Illinois. IAEI, ASHI, and the National Electrical Manufacturing Association are
joining forces get data from each state to give a true picture of the failures
throughout the United States.
The Bottom Line For Safety
If you follow just these two steps, whether at home or at work, you can help
ensure that your GFCIs function as life-protecting devices.
1. Test them monthly as required.
2. When a GFCI trips, reset and then trip it using either a GFCI tester or test
buttons on the device. (Make sure this stops the current flow). Reset and use
the circuit!
Ground-Fault
Protection on Construction Sites
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INSULATION AND GROUNDING
Insulation and grounding are two recognized means of preventing injury
during electrical equipment operation. Conductor insulation may be
provided by placing nonconductive material such as plastic around the
conductor. Grounding may be achieved through the use of a direct
connection to a known ground such as a metal cold water pipe.
Consider, for example, the metal housing or enclosure around a motor or
the metal box in which electrical switches, circuit breakers, and
controls are placed. Such enclosures protect the equipment from dirt and
moisture and prevent accidental contact with exposed wiring. However,
there is a hazard associated with housings and enclosures. A malfunction
within the equipment—such as deteriorated insulation—may create an
electrical shock hazard. Many metal enclosures are connected to a ground
to eliminate the hazard. If a "hot" wire contacts a grounded
enclosure, a ground fault results which normally will trip a circuit
breaker or blow a fuse. Metal enclosures and containers are usually
grounded by connecting them with a wire going to ground. This wire is
called an equipment grounding conductor. Most portable electric tools
and appliances are grounded by this means. There is one disadvantage to
grounding: a break in the grounding system may occur without the user's
knowledge.
Insulation may be damaged by hard usage on the job or simply by aging.
If this damage causes the conductors to become exposed, the hazards of
shocks, burns, and fire will exist. Double insulation may be used as
additional protection on the live parts of a tool, but double insulation
does not provide protection against defective cords and plugs or against
heavy moisture conditions.
The use of a ground-fault circuit interrupter (GFCI) is one method used
to overcome grounding and insulation deficiencies.
WHAT IS A GFCI?
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.
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However, the GFCI will not protect the employee
from line-to-line contact hazards (such as a person holding two
"hot" wires or a hot and a neutral wire in each hand). It does
provide protection against the most common form of electrical shock
hazard--the ground fault. It also provides protection against fires,
overheating, and destruction of insulation on wiring.
WHAT ARE THE HAZARDS?
With the wide use of portable tools on construction sites, the use of
flexible cords often becomes necessary. Hazards are created when cords,
cord connectors, receptacles, and cord- and plug-connected equipment are
improperly used and maintained.
Generally, flexible cords are more vulnerable to damage than is fixed
wiring. Flexible cords must be connected to devices and to fittings so
as to prevent tension at joints and terminal screws. Because a cord is
exposed, flexible, and unsecured, joints and terminals become more
vulnerable. Flexible cord conductors are finely stranded for
flexibility, but the strands of one conductor may loosen from under
terminal screws and touch another conductor, especially if the cord is
subjected to stress or strain.
A flexible cord may be damaged by activities on the job, by door or
window edges, by staples or fastenings, by abrasion from adjacent
materials, or simply by aging. If the electrical conductors become
exposed, there is a danger of shocks, burns, or fire. A frequent hazard
on a construction site is a cord assembly with improperly connected
terminals.
When a cord connector is wet, hazardous leakage can occur to the
equipment grounding conductor and to humans who pick up that connector
if they also provide a path to ground. Such leakage is not limited to
the face of the connector but also develops at any wetted portion of it.
When the leakage current of tools is below 1 ampere, and the grounding
conductor has a low resistance, no shock should be perceived. However,
should the resistance of the equipment grounding conductor increase, the
current through the body also will increase. Thus, if the resistance of
the equipment grounding conductor is significantly greater than 1 ohm,
tools with even small leakages become hazardous.
PREVENTING AND ELIMINATING HAZARDS
GFCIs can be used successfully to reduce electrical hazards on
construction sites. Tripping of GFCIs—interruption of current
flow—is sometimes caused by wet connectors and tools. It is good
practice to limit exposure of connectors and tools to excessive moisture
by using watertight or sealable connectors. Providing more GFCIs or
shorter circuits can prevent tripping caused by the cumulative leakage
from several tools or by leakages from extremely long circuits.
EMPLOYER'S RESPONSIBILITY
OSHA ground-fault protection rules and regulations have been determined
necessary and appropriate for employee safety and health. Therefore, it
is the employer's responsibility to provide either: (a) ground-fault
circuit interrupters on construction sites for receptacle outlets in use
and not part of the permanent wiring of the building or structure; or
(b) a scheduled and recorded assured equipment grounding conductor
program on construction sites, covering all cord sets, receptacles which
are not part of the permanent wiring of the building or structure, and
equipment connected by cord and plug which are available for use or used
by employees.
GROUND-FAULT CIRCUIT INTERRUPTERS
The employer is required to provide approved ground-fault circuit
interrupters for all 120-volt, single-phase, 15- and 20-ampere
receptacle outlets on construction sites which are not a part of the
permanent wiring of the building or structure and which are in use by
employees. Receptacles on the ends of extension cords are not part of
the permanent wiring and, therefore, must be protected by GFCIs whether
or not the extension cord is plugged into permanent wiring. These GFCIs
monitor the current-to-the-load for leakage to ground. When this leakage
exceeds 5 mA ± 1 mA, the GFCI interrupts the current. They are rated to
trip quickly enough to prevent electrocution. This protection is
required in addition to, not as a substitute for, the grounding
requirements of OSHA safety and health rules and regulations, 29 CFR
1926. The requirements which employers must meet, if they choose the
GFCI option, are stated in 29 CFR 1926.404(b)(1)(ii). (See appendix.)
ASSURED EQUIPMENT GROUNDING CONDUCTOR PROGRAM
The assured equipment grounding conductor program covers all cord sets,
receptacles which are not a part of the permanent wiring of the building
or structure, and equipment connected by cord and plug which are
available for use or used by employees. The requirements which the
program must meet are stated in 29 CFR 1926.404(b)(1)(iii), but
employers may provide additional tests or procedures. (See appendix.)
OSHA requires that a written description of the employer's assured
equipment grounding conductor program, including the specific procedures
adopted, be kept at the jobsite. This program should outline the
employer's specific procedures for the required equipment inspections,
tests, and test schedule.
The required tests must be recorded, and the record maintained until
replaced by a more current record. The written program description and
the recorded tests must be made available, at the jobsite, to OSHA and
to any affected employee upon request. The employer is required to
designate one or more competent persons to
implement the program.
Electrical equipment noted in the assured equipment grounding conductor
program must be visually inspected for damage or defects before each
day's use. Any damaged or defective equipment must not be used by the
employee until repaired.
Two tests are required by OSHA. One is a continuity test to ensure that
the equipment grounding conductor is electrically continuous. It must be
performed on all cord sets, receptacles which are not part of the
permanent wiring of the building or structure, and on cord- and
plug-connected equipment which is required to be grounded. This test may
be performed using a simple continuity tester, such as a lamp and
battery, a bell and battery, an ohmmeter, or a receptacle tester.
The other test must be performed on receptacles and plugs to ensure that
the equipment grounding conductor is connected to its proper terminal.
This test can be performed with the same equipment used in the first
test.
These tests are required before first use, after any repairs, after
damage is suspected to have occurred, and at 3-month intervals. Cord
sets and receptacles which are essentially fixed and not exposed to
damage must be tested at regular intervals not to exceed 6 months. Any
equipment which fails to pass the required tests shall not be made
available or used by employees.
SUMMARY
This discussion provides information to help guide employers and
employees in protecting themselves against 120-volt electrical hazards
on the construction site, through the use of ground-fault circuit
interrupters or through an assured equipment grounding conductor
program.
When planning your program, remember to use the OSHA rules and
regulations as a guide to ensure employee safety and health. Following
these rules and regulations will help reduce the number of injuries and
accidents from electrical hazards. Work disruptions should be minor, and
the necessary inspections and maintenance should require little time.
An effective safety and health program requires the cooperation of both
the employer and employees.
If you need additional information planning your program, contact the
OSHA office nearest you.
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Visual
inspection of following:
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cord sets
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cap, plug and receptacle of cord sets
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equipment connected by cord and plug
Exceptions:
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receptacles and cord sets which are fixed and not exposed
to damage
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Frequency of Inspections:
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before each day's use
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Conduct tests
for:
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continuity of equipment grounding conductor
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proper terminal connection of equipment grounding
conductor
Frequency of Tests:
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before first use
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after repair, and before placing back in service
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before use, after suspected damage
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every 3 months, except that cord sets and receptacles that
are fixed and not exposed to damage must be tested at
regular intervals not to exceed 6 months.
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APPENDIX
Construction Safety and
Health Regulations Part 1926 Subpart K (Partial)
§1926.404 Wiring design and protection.
(b) Branch circuits-(1) Ground-fault protection-(i)
General.
The employer shall use either ground-fault circuit interrupters as
specified in paragraph (b)(l)(ii) of this section or an assured
equipment grounding conductor program as specified in paragraph
(b)(l)(iii) of this section to protect employees on construction sites.
These requirements are in addition to any other requirements for
equipment grounding conductors.
(ii) Ground-fault circuit interrupters. All
120-volt, single-phase, 15- and 20-ampere receptacle outlets on
construction sites, which are not a part of the permanent wiring of the
building or structure and which are in use by employees, shall have
approved ground-fault circuit interrupters for personnel protection.
Receptacles on a two-wire, single-phase portable or vehicle-mounted
generator rated not more than 5kW, where the circuit conductors of the
generator are insulated from the generator frame and all other grounded
surfaces, need not be protected with ground-fault circuit interrupters.
(iii) Assured equipment grounding conductor
program. The employer shall establish and implement an assured
equipment grounding conductor program on construction sites covering
cord sets, receptacles which are not a part of the building or
structure, and equipment connected by cord and plug which are available
for use or used by employees. This program shall comply with the
following minimum requirements:
(A) A written description of the program, including the specific
procedures adopted by the employer, shall be available at the jobsite
for inspection and copying by the Assistant Secretary and any affected
employee.
(B) The employer shall designate one or more competent persons [as
defined in §1926.32(f)] to implement the program.
(C) Each cord set, attachment cap, plug and receptacle of cord sets,
and any equipment connected by cord and plug, except cord sets and
receptacles which are fixed and not exposed to damage, shall be
visually inspected before each day's use for external defects, such as
deformed or missing pins or insulation damage, and for indications of
possible internal damage. Equipment found damaged or defective shall
not be used until repaired.
(D) The following tests shall be performed on all cord sets,
receptacles which are not a part of the permanent wiring of the
building or structure, and cord- and plug-connected equipment required
to be grounded:
(1) All equipment grounding conductors shall be tested for
continuity and shall be electrically continuous.
(2) Each receptacle and attachment cap or plug shall be tested for
correct attachment of the equipment grounding conductor. The
equipment grounding conductor shall be connected to its proper
terminal.
(E) All required tests shall be performed:
(1) Before first use;
(2) Before equipment is returned to service following any repairs;
(3) Before equipment is used after any incident which can be
reasonably suspected to have caused damage (for example, when a cord
set is run over); and
(4) At intervals not to exceed 3 months, except that cord sets and
receptacles which are fixed and not exposed to damage shall be
tested at intervals not exceeding 6 months.
(F) The employer shall not make available or permit the use by
employees of any equipment which has not met the requirements of this
paragraph (b)(l)(iii) of this section.
(G) Tests performed as required in this paragraph shall be recorded.
This test record shall identify each receptacle, cord set, and cord-
and plug-connected equipment that passed the test and shall indicate
the last date it was tested or the interval for which it was tested.
This record shall be kept by means of logs, color coding, or other
effective means and shall be maintained until replaced by a more
current record. The record shall be made available on the jobsite for
inspection by the Assistant Secretary and any affected employee.
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