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Electrical Safety Topics

Understanding GFCI and AFCI.pdf



Do You Need An Electrician? Who do you call? What questions do you ask?

10 Questions to Ask Yourself About Your Home Electrical System


When a circuit shuts down repeatedly, it's a warning that should not be ignored.

Are GFCI outlets installed where required?


Are extension cords needed to reach the outlets in any room?


Is there rust on the main electrical service panel?


Do the lights dim when appliances turn on?


Do electrical switches or outlets feel warm or tingly?

Loose or deteriorating electrical connections, such as the wiring junctions in switches and outlets, impede current flow and create resistance. THis may create a dangerous condition that can result in shock or fire.

Do your electrical outlets need accessory plug-strips?

Too many things plugged in at one location can create more current demand than a single outlet or electrical line can safely handle. Adding multiple plug-in strips won't solve the problem. What you need are additional outlets, and possibly new wiring runs to service them.

Do your outlets not accept three-prong plugs?


Is the wiring in your outlet boxes old and crumbling?

If you look at the wiring to your home's light switches or outlets, do you find wires wrapped in cloth sheathing or bits of black rubber in the electrical box? Very old homes often have antiquated wiring that should be upgraded to ensure your safety.

Have you never upgraded your electrical service?


Questions to Ask an Electrician

If you need to consult a professional electrician or electrical contractor, ask the following questions to learn whether the individuals you're considering are fully qualified and likely to do reliable work at a reasonable price.

Are you licensed in this municipality?

Not all states, counties or towns regulate or require licenses for electricians, but it's prudent to check first with your local building department. Also ask if electrical work in your municipality must adhere to standards established by the National Electrical Code.

Will my electrical panel need replacement?

The current National Electrical Code recommends a minimum 100-amp incoming electrical service. If your service panel provides less, it should be upgraded to this level or better to meet today's home requirements. Most new homes are wired with 200-amp service.

Will I have to apply for a permit?

If a permit is required, the electrician often will make the application for the homeowner. Some municipalities allow homeowners to do minor electrical repairs and installations if they first secure a permit and have the work inspected when complete.

Is my home's electrical system adequately grounded?

Ground-wiring protects a home and its occupants in case of an electrical fault, such as a short-circuit. But grounding also protects expensive electronic equipment like computers and many appliances. An electrician can quickly check and add grounding capacity if needed.

Are there any hidden costs for the work?

The electrician should do a thorough preliminary inspection and provide you with a firm, accurate estimate of the work involved, along with the cost of fixtures or wiring that will be installed. If additional work is necessary, it can be negotiated and billed separately.

Will you use all-copper wiring for any new installation?

Solid copper wiring is the material of choice for new homes or renovations. Although 14-gage wire is allowed for many circuits, it's smart to install heavier 12-gage wiring, which costs a little more but can handle more electrical current, making it safer and more energy-efficient.

If my service needs upgrading, will the entire house have to be rewired?

Unless you live in a very old home with antiquated wiring, you probably won't have to replace your existing electrical lines. However, if you require more electrical capacity in certain rooms, new wiring runs and additional outlets are likely to be needed.

Can you provide references from other homeowners?

Every tradesperson or electrician is only as good as their reputation. If you have never contracted with the electrician who answered your call, it's fair to ask for the names of other homeowners who have and to give them a call to check the contractor's work.

Copper Development Association Inc. assumes no responsibility or liability of any kind in connection with this publication, and makes no representations or warranties related to its use, accuracy or utility.

Why GFCI's Fail
(Taken from Occupational Health and Safety Magazine, November 2000
Reprinted with permission © 2000, Stevens Publishing Corporation)

Joseph E. Layton
Stevens Publishing Corp.

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.

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 (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 for protection of equipment or the conductors of a circuit. While grounding is required and is a vital part of the 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 1/1000 th 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.

The adult 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 1/4 th 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.

UL 1943 is the standard for testing GFCIs. Each manufacturer must ensure 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.

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 the 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.

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!

Joseph E. Layton ( is president of Layton’s Electrical Consulting Inc., located in King, N.C. He is a member of the American Society of Safety Engineers, the International Association of Electrical Inspectors, and the National Fire Protection Association.

GFCI 2005 NEC (National Electric code)

210.8 Ground-Fault Circuit-Interrupter Protection for Personnel.

FPN: See 215.9 for ground-fault circuit-interrupter protection for personnel on feeders.
(A) Dwelling Units. All 125-volt, single-phase, 15- and 20-ampere receptacles installed in the locations specified in (1) through (8) shall have ground-fault circuit-interrupter protection for personnel.
(1) Bathrooms
Exception No. 1 to (2): Receptacles that are not readily accessible.
Exception No. 2 to (2): A single receptacle or a duplex receptacle for two appliances located within dedicated space for each appliance that, in normal use, is not easily moved from one place to another and that is cord-and-plug connected in accordance with 400.7(A)(6), (A)(7), or (A)(8).
Receptacles installed under the exceptions to 210.8(A)(2) shall not be considered as meeting the requirements of 210.52(G)
(3) Outdoors
Exception to (3): Receptacles that are not readily accessible and are supplied by a dedicated branch circuit for electric snow-melting or deicing equipment shall be permitted to be installed in accordance with 426.28.
Receptacles installed under the exceptions to 210.8(A)(5) shall not be considered as meeting the requirements of 210.52(G).
(4) Crawl spaces — at or below grade level
Exception No. 1 to (5): Receptacles that are not readily accessible.
(7) Laundry, utility, and wet bar sinks — where the receptacles are installed within 1.8 m (6 ft) of the outside edge of the sink
(8) Boathouses
(B) Other Than Dwelling Units. All 125-volt, single-phase, 15- and 20-ampere receptacles installed in the locations specified in (1) through (5) shall have ground-fault circuit-interrupter protection for personnel:
(1) Bathrooms
(2) Commercial and institutional kitchens — for the purposes of this section, a kitchen is an area with a sink and permanent facilities for food preparation and cooking
(3) Rooftops
(4) Outdoors in public spaces—for the purpose of this section a public space is defined as any space that is for use by, or is accessible to, the public

Exception to (3) and (4): Receptacles that are not readily accessible and are supplied from a dedicated branch circuit for electric snow-melting or deicing equipment shall be permitted to be installed in accordance with the applicable provisions of Article 426.
(5) Outdoors, where installed to comply with 210.63
(C) Boat Hoists. Ground-fault circuit-interrupter protection for personnel shall be provided for outlets that supply boat hoists installed in dwelling unit locations and supplied by 125-volt, 15- and 20-ampere branch circuits.

Aluminum wiring article:

Electrical Safety

  • Find and correct overloaded circuits. 
  • Never place extension cords under rugs. 
  • Outlets near water should be GFI-type outlets. 
  • Don't allow trees near power lines to be climbed. 

Electrical Panels
Outlets and Extension Cords


Electrical Appliances

Electrical Heating Equipment


Electricity and Water

Animal Hazards

Outside Hazards

  • Routinely check your electrical appliances and wiring.
  • Use electrical extension cords wisely and don't overload them.