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Home Inspection FYI - Providing Help, Knowledge and Other Useful Information To Home Owners Everywhere

Tag Archives: receptacle

Ground-Fault Circuit Interrupters (GFCI)

What is a GFCI?

Ground Fault Circuit Interrupters (GFCI)

A ground-fault circuit interrupter, or GFCI, is a device used in electrical wiring to disconnect a circuit when unbalanced current is detected between an energized conductor and a neutral return conductor.

Such an imbalance is sometimes caused by current “leaking” through a person who is simultaneously in contact with a ground and an energized part of the circuit, which could result in lethal shock.  lrg 420 shock1 Ground Fault Circuit Interrupters (GFCI)A GFCI is designed to provide protection in such a situation, unlike standard circuit breakers, which guard against overloads, short circuits and ground faults.

It is estimated that about 300 deaths by electrocution occur every year, so the use of GFCIs has been adopted in new construction, and recommended as an upgrade in older construction, in order to mitigate the possibility of injury or fatality from electric shock.

History of The GFCI

The first high-sensitivity system for detecting current leaking to ground was developed by Henri Rubin in 1955 for use in South African mines.  This cold-cathode system had a tripping sensitivity of 250 mA (milliamperes), and was soon followed by an upgraded design that allowed for adjustable trip-sensitivity from 12.5 to 17.5 mA.  The extremely rapid tripping after earth leakage-detection caused the circuit to de-energize before electric shock could drive a person’s heart into ventricular fibrillation, which is usually the specific cause of death attributed to electric shock.

Charles Dalziel first developed a transistorized version of the ground-fault circuit interrupter in 1961.  Through the 1970s, a GFCI was of the circuit-breaker type.  This version of the GFCI was prone to frequent false trips due to poor alternating-current characteristics of 120-volt insulations.  Especially in circuits with long cable runs, current leaking along the conductors’ insulation could be high enough that breakers tended to trip at the slightest imbalance.

Since the early 1980s, ground-fault circuit interrupters have been built into outlet receptacles, and advances in design in both receptacle and breaker types have improved reliability while reducing instances of “false trips,” known as nuisance-tripping.

NEC Requirements for a GFCI

The National Electrical Code (NEC) has included recommendations and requirements for a GFCI in some form since 1968, when it first allowed a GFCI as a method of protection for underwater swimming pool lights.  Throughout the 1970s, GFCI installation requirements were gradually added for 120-volt receptacles in areas prone to possible water contact, including bathrooms, garages, and any receptacles located outdoors.

The 1980s saw additional requirements implemented.  During this period, kitchens and basements were added as areas that were required to have a GFCI, as well as boat houses, commercial garages, and indoor pools and spas.  New requirements during the ’90s included crawlspaces, wet bars and rooftops.  Elevator machine rooms, car tops and pits were also included at this time.  In 1996, GFCI protection was mandated for all temporary wiring for construction, remodeling, maintenance, repair, demolition and similar activities and, in 1999, the NEC extended GFCI requirements to carnivals, circuses and fairs.

The 2008 NEC contains additional updates relevant to GFCI use, as well as some exceptions for certain areas.  The 2008 language is presented here for reference.

2008 NEC on GFCI Protection

100.1 Definition

100.1  Definitions. “GFCI” Ground-Fault Circuit Interrupter. A device intended for the protection of personnel that functions to de-energize a circuit or portion thereof within an established period of time when a current to ground exceeds the values established for a Class A device.

FPN: Class A ground-fault circuit interrupters trip when the current to ground has a value in the range of 4 mA to 6 mA.  For further information, see UL 943, standard for Ground-Fault Circuit Interrupters.

210.8(A)&(B)  Protection for Personnel

210.8 Ground-Fault Circuit Interrupter Protection for Personnel.

(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; (2)   garages, and also accessory buildings that have a floor located at or below grade level not intended as habitable rooms and limited to storage areas, work areas, and areas of similar use;

Exception No. 1: Receptacles not readily accessible.

Exception No. 2: A single receptacle or a duplex receptacle for two appliances 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: 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 the applicable provisions of Article 426.

(4)   crawlspaces at or below grade level;

(5)   unfinished basements.  For the purposes of this section, unfinished basements are defined as portions or areas of the basement not intended as habitable rooms and limited to storage areas, work areas, and the like;

Exception No. 1: Receptacles that are not readily accessible.

Exception No. 2:  A single receptacle or a duplex receptacle for two appliances 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).

Exception No. 3: A receptacle supplying only a permanently installed fire alarm or burglar alarm system shall not be required to have ground-fault circuit interrupter protection.

Receptacles installed under the exceptions to 210.8(A)(2) shall not be considered as meeting the requirements of 210.52(G)

(6)   kitchens, where the receptacles are installed to serve the countertop surfaces;

(7)   wet bar sinks, where the receptacles are installed to serve the countertop surfaces and are located within 6 feet (1.8 m) of the outside edge of the wet bar 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), (2), and (3) shall have ground-fault circuit interrupter protection for personnel:

(1)   bathrooms;

(2)   rooftops;

Exception: Receptacles that are not readily accessible and are supplied by a dedicated branch circuit for electric snow-melting or de-icing equipment shall be permitted to be installed in accordance with the applicable provisions of Article 426.

(3)   kitchens.

Testing Receptacle-Type GFCI

A receptacle-type GFCI is currently designed to allow for safe and easy testing that can be performed without any professional or technical knowledge of electricity.  Every GFCI should be tested right after installation to make sure the GFCI is working properly and protecting the circuit.  A GFCI should also be tested once a month to make suGFCI receptacle1 Ground Fault Circuit Interrupters (GFCI)re they are working properly and are providing protection from fatal shock.

To test the receptacle GFCI, first plug a nightlight or lamp into the outlet. The light should be on.  Then press the “TEST” button on the GFCI. The “RESET” button should pop out, and the light should turn off.

If the “RESET” button pops out but the light does not turn off, the GFCI has been improperly wired. Contact an electrician to correct the wiring errors.

If the “RESET” button does not pop out, the GFCI is defective and should be replaced.

If the GFCI is functioning properly and the lamp turns off, press the “RESET” button to restore power to the outlet.

Ground Fault Circuit Interrupters (GFCI)
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Arc-Fault Circuit Interrupters

Arc-Fault Circuit Interrupters

Arc-fault circuit interrupters (AFCIs) are special types of electrical receptacles or outlets and circuit breakers designed to detect and respond to potentially dangerous electrical arcs in home branch wiring.receptacles 300x201 Arc Fault Circuit Interrupters

 

How do Arc-fault circuit interrupters work?

 

Arc-fault circuit interrupters (AFCIs) function by monitoring the electrical waveform and promptly opening (interrupting) the circuit they serve if they detect changes in the wave pattern that are characteristic of a dangerous arc. Arc-fault circuit interrupters also must be capable of distinguishing safe, normal arcs, such as those created when a switch is turned on or a plug is pulled from a receptacle, from arcs that can cause fires. An AFCI can detect, recognize, and respond to very small changes in wave pattern.

What is an arc?

When an electric current crosses an air gap from an energized component to a grounded component, it produces a glowing plasma discharge known as an arc. For example, a bolt of lightening is a very large, powerful arc that crosses an atmospheric gap from an electrically charged cloud to the ground or another cloud. Just as lightning can cause fires, arcs produced by domestic wiring are capable of producing high levels of heat that can ignite their surroundings and lead to structure fires.

According to statistics from the National Fire Protection Agency for the year 2005, electrical fires damaged approximately 20,900 homes, killed 500 people, and cost $862 million in property damage. Although short-circuits and overloads account for many of these fires, arcs are responsible for the majority and are undetectable by traditional (non-AFCI) circuit breakers.

Where are arcs likely to form?

Arcs can form where wires are improperly installed or when insulation becomes damaged. In older homes, wire insulation tends to crystallize as it ages, becoming brittle and prone to cracking and chipping. Damaged insulation exposes the current-carrying wire to its surroundings, increasing the chances that an arc may occur.

Situations in which arcs may be created:

  • electrical cords damaged by vacuum cleaners or trapped beneath furniture or doors.
  • damage to wire insulation from nails or screws driven through walls.
  • appliance cords damaged by heat, natural aging, kinking, impact or over-extension.electrical arc inspect Arc Fault Circuit Interrupters
  • spillage of liquid.
  • loose connections in outlets, switches and light fixtures.

Where are Arc-fault circuit interrupters (AFCIs) required?

Locations in which Arc-fault circuit interrupters (AFCIs) are required depend on the building codes adopted by their jurisdiction. Inspectors are responsible for knowing what building codes are used in the areas in which they inspect.

The 2006 International Residential Code (IRC) requires that Arc-fault circuit interrupters (AFCIs) be installed within bedrooms in the following manner:

E3802.12 Arc-Fault Protection of Bedroom Outlets. All branch circuits that supply120-volt, single-phase, 15- and 20-amp outlets installed in bedrooms shall be protected by a combination-type or branch/feeder-type arc-fault circuit interrupter installed to provide protection of the entire branch circuit.

Exception: The location of the arc-fault circuit interrupter shall be permitted to be at other than the origination of the branch circuit, provided that:
  1. The arc-fault circuit interrupter is installed within 6 feet of the branch circuit overcurrent device as measured along the branch circuit conductors, and
  2. The circuit conductors between the branch circuit overcurrent device and the arc-fault circuit interrupter are installed in a metal raceway or a cable with metallic sheath.

The National Electrical Code (NEC) offers the following guidelines concerning Arc-fault circuit interrupters (AFCIs) placement within bedrooms:

Dwelling Units. All 120-volt, single phase, 15- and 20-ampere branch circuits supplying outlets installed in dwelling unit in family rooms, dining rooms, living rooms, parlors, libraries, dens, sun rooms, recreation rooms, closets, hallways, or similar rooms or areas shall be protected by a listed arc-fault circuit interrupter, combination-type installed to provide protection of the branch circuit.

Some jurisdictions do not yet require their implementation in locations where Arc-fault circuit interrupters (AFCIs) can be helpful.afci inspection Arc Fault Circuit Interrupters

What types of Arc-fault circuit interrupters (AFCIs) are available?

 

The four most common types of AFCIs are as follows:

  • Branch/feeder—installed at the main electrical panel or sub-panel.
  • Outlet circuit—installed in a branch-circuit outlet.
  • Combination—complies with the requirements of both the branch/feeder and the outlet circuit AFCIs.
  • Cord—a plug-in device connected to the receptacle outlet.

Nuisance Tripping

An Arc-fault circuit interrupters (AFCIs) might activate in situations that are not dangerous and create needless power shortages. This can be particularly annoying when an Arc-fault circuit interrupters (AFCIs) stalls power to a freezer or refrigerator, allowing its contents to spoil. There are a few procedures an electrical contractor can perform in order to reduce potential “nuisance tripping,” such as:

  • Check that the load power wire, panel neutral wire and load neutral wire are properly connected.
  • Check wiring to ensure that there are no shared neutral connections.
  • Check the junction box and fixture connections to ensure that the neutral conductor contacts a grounded conductor.

Arc-fault circuit interrupters (AFCIs)  vs. Ground Faults

It is important to distinguish AFCI devices from Ground Fault Circuit Interrupter (GFCI) devices. GFCIs detect ground faults, which occur when current leaks from a hot (ungrounded) conductor to a grounded object as a result of a short-circuit. This situation can be hazardous when a person unintentionally becomes the current’s path to the ground. GFCIs function by constantly monitoring the current flow between hot and neutral (grounding) conductors, and activate when they sense a difference of 5 milliamps or more. Thus, GFCIs are intended to prevent personal injury due to electric shock, while AFCIs prevent personal injury and property damage due to structure fires.

Arc-fault circuit interrupters (AFCIs) are designed to detect small arcs of electricity before they have a chance to lead to a structure fire.

 

Arc-fault circuit interrupters (AFCIs)

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AFCI Testers

AFCI Testers and How They Work

What is an AFCI?

 
Arc-fault circuit interrupters (AFCIs) are special types of electrical receptacles (or outlets) and circuit breakers designed to detect and respond to potentially dangerous electrical arcs in home branch wiring.afci indicator nspection AFCI Testers

What are AFCI testers or indicators?

 
AFCI tester indicators (sometimes called AFCI testers) are portable devices designed to test the AFCI‘s functionality. They create waveform patterns similar to those produced by actual arc faults, thereby causing working AFCIs to trip. These indicators are considerably larger and more expensive (by several hundred dollars) than  ground-fault circuit interrupter (GFCI) indicators and are of questionable effectiveness. For these reasons, they are not used as widely as GFCI indicators.

Why are AFCI indicators important?

 
While an AFCI circuit breaker comes with a test button that performs a role similar to a portable AFCI indicator, this button cannot test for arc faults within individual portions of the branch circuit. An AFCI indicator, however, can test any individual receptacle within the branch. InterNACHI inspectors should use AFCI indicators to inspect receptacles observed and deemed to be AFCI-protected.

How do AFCI indicators work?

 
AFCI indicators should be inserted directly into the receptacle. Some indicators, such as the popular #61-165 model produced by Ideal™, offer a number of testing options. This indicator creates eight to 12 pulses of 106 to 141 amp charges in less than a second which should be recognized by the AFCI as a dangerous arc and cause it to open the circuit that it serves. The indicator can also test for nuisance tripping, the annoying tendency of an AFCI to open its circuit when it detects a safe, shared neutral connection. For this test, it produces a 300mA arc that should not cause AFCI’s to trip. Some other indicators conveniently incorporate a GFCI indicator into their design.
AFCI indicators are somewhat larger than GFCI indicators but they are operated in the same way. An inspector simply inserts one into a receptacle and navigates the menu in order to produce the desired electric current. The user will know that the circuit in question has been tripped if the AFCI device loses power. If this occurs following an AFCI test, the AFCI is functioning properly. The user should then go to the electrical panel to reset the AFCI breaker. If the test results in the failure of an AFCI breaker to open the circuit, then a qualified electrician should be contacted.

How effective are AFCI indicators?

 
It is important to understand the distinction between an AFCI indicator and the test button on an AFCI device. The latter produces an actual arc fault and can be relied upon to assess the functionality of the AFCI. An indicator, by contrast, creates waveforms that are not true arcs but are characteristic of them and are thus not a completely reliable measure of an AFCI’s functionality. As a result of this distinction, an indicator might not cause a perfectly functional AFCI to trip. Although commonly called testers, it is more appropriate to refer to them as indicators, despite terminology that often appears in AFCI “tester” user guides.
Underwriters Laboratories, a product-testing organization that develops product standards, requires AFCI indicators to include the following information detailing this limitation in their product manuals:
CAUTION:  AFCIs recognize characteristics unique to arcing, and AFCI indicators produce characteristics that mimic some forms of arcing. Because of this, the indicator may give a false indication that the AFCI is not functioning properly. If this occurs, recheck the operation of the AFCI using the test and reset buttons. The AFCI button test function will demonstrate proper operation.
This caution implies that an AFCI’s working properly if the indicator causes it to trip, but the reverse is not necessarily true.  AFCI’s that do not trip as a result of an indicator may actually be perfectly fine. The test button on the circuit interrupter can be used to confirm its malfunction in the event that the indicator does not cause it to trip. Manufacturers claim that their AFCI indicators provide a universal method to test AFCIs that are produced by different companies.

In summary, AFCI indicators help ensure that AFCIs are properly monitoring the circuits that they serve for dangerous arc faults. These devices create electrical waveforms characteristic of those produced by an actual arc. As their effectiveness has been debated, they should be viewed as a complement to the test button on an AFCI, rather than a substitute.

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