The Functions, Uses and Proper Installation of Ground Fault Circuit Interrupting Outlets
At the end of the lesson, you will be able to:
Cognitive Domain
Identify the what is Ground Fault Circuit Interrupting outlets as the tools and ways used in installing Ground Fault Circuit Interrupting outlets.
Affective Domain
Discuss what is ground fault, what are the effects of ground fault and how a ground fault circuit interrupting outlet works.
Psychomotor Domain
Perform installation and testing of a Ground Fault Circuit Interrupting outlet
Let's Watch!
Let's Practice!
Activity 3.0
PERFORMANCE TASK ACTIVITY:
Installing a GFCI Outlet using a Conventional Outlet as an alternative
A. Materials:
Wire stripper
Combination Plier
Long nose plier
Flat screw and star screw driver
Testing bulb
Electric wires
Wiring board (already prepared by the school/teacher)
Conventional outlet
B. Activity Proper
You will be performing a mock-up practice activity using an alternative conventional outlet with the materials being prescribed above, you will be performing this activity on the school where mostly all of your materials needed for this activity are available.
Perform installation using the alternative conventional outlet by following the demonstrational video given above. You will be asked to install the conventional outlet on the wiring board so that you don't have to install electrical wiring in this activity.
After you have installed the outlet, perform testing by plugging the test light bulb on the outlet. The teacher will grade you base on the given criteria.
Criteria:
Speed 20
Accuracy: 35
Workmanship: 45
Let's Explore!
Have you ever experienced the following scenario?
It was just a normal morning school-day routine for you, you wake-up from the bed, take a bath, change clothes, and headed to kitchen for a breakfast, but, this time, you forgot to iron your type-A polo uniform beforehand, so, you get the iron from the closet, and plug it on a socket. However, at the moment the plug gets inserted into the socket, you experience a surprising electric shock, which triggers your reflexes to drop the iron on the floor. You feel the electricity travels throughout your body, which gives you a painful and surprising shock. You’ve been thinking about what just happened and immediately pull the plug on the socket. “What was that?” You said to yourself, you picked-up the unplugged iron and saw that there was a broken wire inside it that makes contact with the outer metal casing of the iron from which you’ve been holding on.
What you have just experienced is called electric shock. It is very common especially when our hand is wet and makes contact on any socket, or if there is a damage on the appliances and you unknowingly touched the metal casing that has been electrified due to damage in electrical wirings inside it, and any other instances that may took place in your house, school, workplace and public places. Have you ever experienced any of this scenario? If yes, then you are not alone.
Electricity, in its nature, clings to travel to any available short pathway with minimal amount of resistance. Resistance is the ability to resist any flow of current that flows through a circuit, conductors like copper and many metals, have less resistance, so electricity can freely travel through them. On the other hand, ground is defined as an alternative, low resistance pathway for the excess electricity or current to flow, especially in an event of electrical surge or any damage to appliances. Ground serves as a bleeding system that allows the excess amount of current in the system to bleed to the ground. However, in your scenario, there is no other way for the current to flow, so it stays on the metal casing, until you provide the shortest pathway to the ground, this is called ground fault. In addition, your iron did not have a ground prong or your receptacle had a ground gang (third hole in a socket), which is a common scenario among appliances and sockets in the Philippines. A grounded prong or plug, has 3 components; hot wire, neutral and ground. Have you ever seen this kind of plug? This is very common on imported appliances, phone and laptop chargers, usually when we use them, we use another socket to convert the 3 prong plug into 2 prong plug we usually called it adaptor, or else we remove them, because our sockets here in the Philippines, has only two gangs (two-holes in a socket).
About 200 people died each year in America during the 1950’s to 60’s due to ground fault. Facing these problems, a professor in Electrical Engineering at the University of California named Charles Dalziel, invented the GFCI (Ground Fault Circuit Interrupter) in 1961. His device monitors the difference in current flowing in and out of a circuit, however, if it detects an increase of difference in current in the circuit within 5 milliamps, it automatically terminates the current flowing in the circuit within 0.25 seconds. Preventing any further risk and casualty in the workplace or in the house. Because of its unique capability, it is commonly used in kitchen and outdoor connections where most of the danger in electricity due to wet and damp surfaces commonly occurs. GFCI has been widely used for such applications because of its unique capabilities in comparison to an ordinary outlet. The discussion below will give you a much detailed information on the workings and concepts of GFCI.
Did You Know?
The word “electrocution” is derived from two English word “electro” and “execution” which means “execution by electricity”. The first electrocution being recorded in history was performed against William Kemmler as a capital punishment, who is convicted of murdering his lover Matilda Ziegler with an axe
Let's Read!
The illustration above shows the different levels of current an its corresponding effects to the human body.
One of the characteristics of electricity is to seek any available short pathway to travel. If a person makes contact with an electrified surface such as an outer metal covering of any appliances like refrigerators, electric iron, electric stove and many more, he or she provides a short pathway for the electricity to travel to the ground, this is called ground fault. This kind of scenario is very common to every household, especially to places where damp and wet surfaces exist. The degree of current flowing through a person's body depends on the situation or condition at the point of contact. If a person is standing on wet or damp surfaces like in a kitchen or bathroom with bare feet, the risk is much higher than a person with the same situation standing with thick rubber soles on shoes. That is the reason why, people responsible in electrical works and maintenance are required to wear thick shoes with rubber insulation (PPE’s) to protect them from getting at risk in work. Are you familiar with personal protective equipment? Electricity is so dangerous that it only takes a small amount of current to kill a person, exposure to a current rating of 100milliamps for 2 seconds is enough to kill that person especially if it travels to the chest cavity. To give you an idea, the illustration above shows the different levels of current and its corresponding effect on the human body.
With the increasing cases of ground fault in the U.S during the 1961, an American Electrical Engineering professor Charles Dalziel, invented the GFCI to alleviate the rising problem of ground fault accidents. Dalziel estimated the electrical shock hazards to humans and developed a safe current time envelope for ventricular fibrillation and used this information to design his GFCI. Dalziel's GFCI used a transistor to provide quick detection of tripping times for current imbalances. Early GFCI's were integrated into circuit breakers. Later, the circuitry was added to duplex electrical outlets and has become popularly used for residential purposes. The NEC (National Electrical Code) requires GFCI devices to protect people by interrupting current flow, if the current leakage exceeds more than 5 milliamps. Also, GFCI devices which protect equipment are allowed to trip as high as 30milliamp of current.
GFCI also known as Ground Fault Circuit Interrupting is a fast- acting circuit breaker which measures and monitors small imbalances in the circuit caused by current leakage to ground within a fraction of seconds.
How does GFCI work?
Generally, during a normal operation of an electrical appliance, the current flowing through the conductor into a GFCI outlet, is equal to the flow of current returning from the appliance to the GFCI. However, if there is a "short circuit" that occurs in the appliance there is an imbalance in current, once the GFCI detects the imbalance, the GFCI will terminate the flow of current to prevent any further damage or casualty. For instance, the scenario that has been mentioned in the previous discussion is an excellent example of ground fault. The outer protective insulator of a hot wire inside the electric iron is damaged which causes the wire to be exposed and make contact to the outer metallic casing of the electric iron, because the electricity has no other way to exit, electric shock happens the moment the victim touches the electric iron. However, this could be averted, if the victim uses a GFCI outlet. The contact between metallic casing and the exposed wire causes imbalances to the current which will cause the GFCI outlet to tripped-off. Thereby, eliminating the risk of electrocution. The image in Figure 1.0 will give you an idea about the function of a GFCI outlet.
Figure 1.0 The internal circuit of a Ground Fault Circuit Interrupting Outlets.
Figure 1.0 shows the internal circuit of a Ground Fault Circuit Interrupting outlet. The receptacle is connected to a 120 volts source from the main panel. Under normal condition, the electricity from the main panel passes through the hot wire of the GFCI circuit and induces current on the current transformer (circular loop of wire) which sends signal to the electronic sensor (Solid-state circuitry) and registers the amount of current that flows within the hot wire, the current then flows to the appliances and back to the outlet through the neutral wire. The neutral wire also induces current to the current transformer (circular loop of wire) which sends signal to the same sensor and registers the same amount of current that passes through the hot wire. Since the amount of current that flows through the neutral wire is the same amount of current that flows through the hot wire, the sensor will not terminate the circuit. However, when a ground fault (current leaking) occurs the GFCI will detect the current imbalance (the amount of current that flows in the hot wire is not the same amount of current that flows in the neutral wire) which tells the sensor to terminate the flow of current. To test if your GFCI outlet is still functioning, press the test button. The test button will create a current imbalance (by passing the current from the hot wire through a 5mA test operational resistor) which will be detected by the current transformer and sends signal to the electronic circuit to terminate the flow of current. The outlet will remain shut until the reset button is pressed to fully reset the outlet, this is for safety purpose in order to prevent accidental electrocution.
Can GFCI devices really prevent electrocution?
Yes, but there is also an interesting fact about the nature of electricity that prevents GFCI devices from functioning well. GFCI devices are like a miniaturized circuit beaker that automatically opens the circuit and terminate the flow of current when it detects current imbalance within the circuit. However, due to the fact that electricity travels at the speed of light, no man-made devices can act as fast as or faster than the speed of light, as result you will still experience a little amount of shock.
Where do GFCI devices commonly used?
As a general rule GFCI devices are commonly used or installed in wet/damp places like kitchen, bathrooms, garage, crawl spaces, unfinished basements, and outdoor applications where ground fault accidents are most likely to occur. In addition, GFCI devices can also be installed anywhere inside your house for added protection. If your home was constructed prior to the mid 70’s there is a good chance GFCI devices were not installed in your home. Your receptacles can be updated by a qualified electrician. The main reason for not installing GFCI devices throughout a home is cost, but it is highly recommended you update the devices in your bathroom and kitchen areas at a minimum.
Where GFCI's should be considered?
In homes built to comply with the National Electrical Code, GFCI protection is required for most outdoor receptacles (since 1973), bathroom receptacle circuits (since 1975), garage wall outlets (since 1978), kitchen receptacles (since 1987), and all receptacles in crawl spaces and unfinished basements (since 1990). Owners of homes that do not have GFCl's installed in all those critical areas specified in the latest version of the Code should consider having them installed. For broad protection, GFCI circuit breakers may be added in many panels of older homes to replace ordinary circuit breaker. For homes protected by fuses, you are limited to receptacle or portable-type GFCIs and these may be installed in areas of greatest exposure, such as the bathroom, kitchen, basement, garage, and outdoor circuits. A GFCI should be used whenever operating electrically powered garden equipment (mower, hedge trimmer, edger, etc.). Consumers can obtain similar protection by using GFCIs with electric tools (drills, saws, sanders, etc.) for do-it-yourself work in and around the house.
TYPES OF GROUND FAULT CIRCUIT INTERRUPTING DEVICES
Receptacle GFCI
Is used in place of a regular wall outlet or “duplex receptacle”. This kind of GFCI is commonly found in kitchen, bathrooms, garage and other outdoor areas where wet and damp surfaces usually occur.
Temporary/Portable GFCI
Is used when the GFCI outlet is not applicable. Portable GFCI is an extension cord version of a GFCI outlet which allows you to plugged-in into unprotected outlets and provides protection to your devices and appliances.
Circuit Breaker GFCI
Is a circuit breaker version of GFCI outlet, unlike an ordinary circuit breaker. Circuit breaker GFCI have a dual function, it terminates power in an event of ground fault and turns off the power if there is a short circuit being detected. It is also frequently used in outdoor settings where electrical tools and appliances are being used.
METHODS OF INSTALLING GFCI OUTLETS
(TAILED WIRING METHOD)
1. Connect the GFCI Hot and Neutral Wires
A. Splice the black hot wires from the incoming and outgoing cables, with a pigtail. On the back of the GFCI receptacle is an area that is labeled "LINE," or "LINE IN"; at this location, attach the black pigtail wire to the terminal that is labeled "HOT." Cap the splice with a wire connector.
B. Using another wire connector, splice the white neutral cable wires and pigtail them to the back of the GFCI receptacle at the terminal labeled "WHITE" in the area that is also labeled "LINE."
Note: "LINE" or "LINE IN" on the back of the GFCI receptacle indicates that the wires from the power source are to be connected at this location. The "LOAD" area on the GFCI receptacle is for wiring connections that enable outlets further down the circuit to be protected by this GFCI. If the "LINE" connections (wires coming in from the power source) are attached at the wrong location on the GFCI, it can possibly destroy the GFCI, and will not provide protection.
A. Splice the bare-copper cable ground wires from the cables together, and then pigtail them to the green GFCI receptacle grounding screw. If the electrical box is metal, include in the splice a pigtail ground wire that connects to the ground screw on the metal box.
B. Install the GFCI receptacle, and then turn on the power. Using a circuit tester, test the circuit for power.
A. Test the GFCI to determine if it is
operational. Press the test button--the reset button should pop out. Then reset the GFCI by pressing in the reset button.
METHODS OF INSTALLING GFCI OUTLETS
(Feed Through Wiring Method)
COMMON TOOLS USED IN INSTALLING OUTLET
Flat Screwdrivers
The standard, or conventional screwdriver is used for screws with slotted heads. This screwdriver is usually classified according to tip width and blade length.
Phillips Screw driver
A Phillips screwdriver has four blades used to install Phillips-head screws. The tip looks like a plus sign.
Electrical tape
It refers to a thick adhesive pressure-sensitive tape used to insulate electrical wires and other materials that conduct electricity.
Needle-nose Pliers
It will be used for bending and twisting wires whenever you are making screw-terminal connections. The long, narrow tip makes this a great tool for detailed work.
Non-contact Voltage Tester
Perhaps the most important specialty electrical tool you can own is a voltage tester. A voltage tester is used for a quick safe check to make sure there's no voltage in an electrical wire or device before you start working on it. Non-contact voltage testers, powered by batteries, are the simplest and safest types of testers because they can detect electricity just by being near an outlet slot or wire.
Voltmeter or Multitester
A voltmeter is used to read voltage levels and verify that circuits are “live” or off. Unlike a circuit tester, this tool gives you reading on how much voltage is being carried. More sophisticated forms of the tool are known as multimeters, and they can not only read voltage levels but also amperage, resistance, and DC voltage and amperage.
Utility Knife
A utility knife, or box cutter, is handy for cutting sheathing from non-metallic (Romex) cable, to cut off electrical tape, and to open cardboard boxes.
Linemen's Side Cutting Pliers
A pair of linesman pliers is an electrician's do-it-all tool. It has a squared-off end that is great for twisting wires together, a center cutting blade for trimming wire, and a grip area between the handles for pulling wire.
Wire Stripper/Cutter
Wire strippers are used to cut and strip insulation from electrical wires. A wire stripper tool has a row of gauged holes for stripping wires of different sizes, and it usually includes cutting jaws for trimming the wire ends.
Diagonal Cutter
Diagonal cutting pliers, sometimes called side snips or dikes, are used to cut wires. They are specially designed with a cutting edge that goes down to the tip of the jaws, allowing you to get into tight areas to trim wires.
Long nose Pliers
It is designed for electrical, telephone and electronic work involving smaller wire gauges. They will reach into awkward places and perform work difficult with any other tool. Their usefulness, however, is not limited to wire work.
Flat nose Plier
Flat-nose pliers are both cutting and holding pliers used by artisans, jewelry designers, electricians, network engineers and other tradesmen to bend, re-position and snip wire.
Slip joint Pliers
This versatile tool is designed for a
wide range of service involving
gripping, turning and bending.
Hammer
A hammer is used to secure electrical boxes equipped with nail-on brackets to wall studs and other framing members in a home. You’ll also need one to drive wire staples when anchoring new electrical cable to framing members.
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Let's Do It!
Engagement Activity 3.0
Engagement Activity 3.0
Perform Installation of GFCI Outlet
A. Materials:
GFCI outlet (required)
Wire stripper
Long Nose Plier
Phillips Screw Driver/Flat Screw Driver
Testing Bulb
Electric Wires
Wiring Board
B. Activity Proper:
For this activity, you will be installing and testing a real GFCI outlet, using the same materials you used in the previous activity. You have to install the GFCI outlet using this materials on the wiring board.
You can use any of the methods that is being discussed previously. You will be performing this at school where all of the equipment and tools are present.
The teacher will be grading you base on this criteria.
Criteria:
Speed 20
Accuracy: 35
Workmanship: 45
Let's Enhance!
Video Enhancements
Reading Enhancements
For further reading:.
2. https://home.howstuffworks.com/question117.htm
3. https://www.dfliq.net/blog/what-is-gfci-outlet/
5. https://cpsc.gov/s3fs-public/099_0.pdf
6.http://mmiresource.hotelpros.biz/files/docs_801_900/820/gfci_fact_sheet.pdf
7.https://www.leviton.com/en/docs/Self-test_Lev-Lok.pdf
References
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