A Medley of Potpourri

Monday, August 15, 2022

Native American cultures in the United States

From Wikipedia, the free encyclopedia

https://en.wikipedia.org/wiki/Native_American_cultures_in_the_United_States

North American ethnic regions

Native American cultures across the United States are notable for their wide variety and diversity of lifestyles, regalia, art forms and beliefs. The culture of indigenous North America is usually defined by the concept of the Pre-Columbian culture area, namely a geographical region where shared cultural traits occur. The northwest culture area, for example shared common traits such as salmon fishing, woodworking, large villages or towns and a hierarchical social structure.

Though cultural features, language, clothing, and customs vary enormously from one tribe to another, there are certain elements which are encountered frequently and shared by many tribes. Early European American scholars described the Native Americans as having a society dominated by clans.

European colonization of the Americas had a major impact on Native American culture through what is known as the Columbian exchange. The Columbian exchange, also known as the Columbian interchange, was the widespread transfer of plants, animals, culture, human populations, technology, and ideas between the Americas and the Old World in the 15th and 16th centuries, following Christopher Columbus's 1492 voyage. The Columbian exchange generally had a destructive impact on Native American culture through disease, and a 'clash of cultures', whereby European values of private property, the family, and labor led to conflict, appropriation of traditional communal lands and slavery.

In the early years, as these native peoples encountered European explorers and settlers and engaged in trade, they exchanged food, crafts, and furs for blankets, iron and steel implements, horses, trinkets, firearms, and alcoholic beverages. Today, while remaining faithful to their traditions, Native American cultures continue to evolve and adapt to changing circumstances.

Cultural areas

Native Americans in the United States fall into a number of distinct ethno-linguistic and territorial phyla, whose only uniting characteristic is that they were in a stage of either Mesolithic (hunter-gatherer) or Neolithic (subsistence farming) culture at the time of European contact.

They can be classified as belonging to a number of large cultural areas:

Continental U.S.
Alaska Natives
- Arctic: Eskimo–Aleut
- Subarctic: Northern Athabaskan
Hawaiians

Language

Early indigenous languages in the U.S.

There are approximately 296 spoken (or formerly spoken) indigenous languages north of Mexico, 269 of which are grouped into 29 families.

The major ethno-linguistic phyla are:

The Na-Dené, Algic, and Uto-Aztecan families are the largest in terms of number of languages. Uto-Aztecan has the most speakers (1.95 million) if the languages in Mexico are considered (mostly due to 1.5 million speakers of Nahuatl); Na-Dené comes in second with approximately 200,000 speakers (nearly 180,000 of these are speakers of Navajo), and Algic in third with about 180,000 speakers (mainly Cree and Ojibwe). Na-Dené and Algic have the widest geographic distributions: Algic currently spans from northeastern Canada across much of the continent down to northeastern Mexico (due to later migrations of the Kickapoo) with two outliers in California (Yurok and Wiyot). The remaining 27 languages are either isolates or unclassified), such as Penutian languages, Hokan, Gulf languages and others.

Organization

Zuni girl with pottery jar on her head in 1909

Gens structure

Early European American scholar described the Native Americans (as well as any other tribal society) as having a society dominated by clans or gentes (in the Roman model) before tribes were formed. There were some common characteristics:

The right to elect its sachem and chiefs.
The right to depose its sachem and chiefs.
The obligation not to marry in the gens.
Mutual rights of inheritance of the property of deceased members.
Reciprocal obligations of help, defense, and redress of injuries.
The right to bestow names on its members.
The right to adopt strangers into the gens.
Common religious rights, query.
A common burial place.
A council of the gens.

Tribal structure

Subdivision and differentiation took place between various groups. Some functions and attributes of tribes are:

The possession of the gentes.
The right to depose these sachems and chiefs.
The possession of religious faith and worship.
A supreme government consisting of a council of chiefs.
A head-chief of the tribe in some instances.

Traditional diet

Maize grown by Native Americans

Chippewa baby waits on a cradleboard while parents tend rice crops (Minnesota, 1940).

The traditional diet of Native Americans has historically consisted of a combination of agriculture, hunting, and the gathering of wild foods, variable by bioregion.

Post-contact, European settlers in the northeastern region of the Americas observed that some of the Indigenous peoples cleared large areas for cropland. These fields in New England sometimes covered hundreds of acres. Colonists in Virginia noted thousands of acres under cultivation by Native Americans.

Native Americans commonly used tools such as the hoe, maul, and dibber. The hoe was the main tool used to till the land and prepare it for planting; then it was used for weeding. The first versions were made out of wood and stone. When the settlers brought iron, Native Americans switched to iron hoes and hatchets. The dibber was a digging stick, used to plant the seed. Once the plants were harvested, women prepared the produce for eating. They used the maul to grind the corn into mash. It was cooked and eaten that way or baked as corn bread.

Religion

Kateri Tekakwitha, the patron of ecologists, exiles, and orphans, was beatified by the Roman Catholic Church.

Baptism of Pocahontas was painted in 1840. John Gadsby Chapman depicts Pocahontas, wearing white, being baptized with the new name, Rebecca, by Anglican minister Alexander Whiteaker in Jamestown, Virginia; this event is believed to have taken place in 1613 or 1614.

Traditional Native American ceremonies are still practiced by many tribes and bands, and the older theological belief systems are still held by many of the traditional people. Many Plains tribes have sweatlodge ceremonies, though the specifics of the ceremony vary among tribes. Fasting, singing and prayer in the ancient languages of their people, and sometimes drumming are also common.

The Midewiwin Lodge is a traditional medicine society inspired by the oral traditions and prophesies of the Ojibwa (Chippewa) and related tribes.

Another significant religious body among some Native Americans is the Native American Church. It is a syncretistic church incorporating elements of Native spiritual practice from a number of different tribes. Some varieties also include elements from Christianity. Its main rite is the peyote ceremony. Prior to 1890, traditional religious beliefs included Wakan Tanka. In the American Southwest, especially New Mexico, a syncretism between the Catholicism brought by Spanish missionaries and the Indigenous religions is common; the religious drums, chants, and dances of the Pueblo people are regularly part of Masses at Santa Fe's Saint Francis Cathedral. Native American-Catholic syncretism is also found elsewhere in the United States. (e.g., the National Kateri Tekakwitha Shrine in Fonda, New York and the National Shrine of the North American Martyrs in Auriesville, New York).

The eagle feather law (Title 50 Part 22 of the Code of Federal Regulations) stipulates that only individuals of certifiable Native American ancestry enrolled in a federally recognized tribe are legally authorized to obtain eagle feathers for religious or spiritual use. The law does not allow Native Americans to give eagle feathers to non-Native Americans.

Gender roles

Dr. Susan La Flesche Picotte was the first Native American woman to become a physician in the United States.

Gender roles can vary significantly between tribal nations, with patriarchal, matriarchal, and egalitarian traditions historically present among the over 500 federally-recognized tribes. Many tribes, such as the Haudenosaunee Five Nations and the Southeast Muskogean tribes, had matrilineal systems, in which property and hereditary leadership were controlled by and passed through the maternal lines. Others were patrilineal tribes, such as the Omaha, Osage and Ponca, where hereditary leadership passed through the male line, and children were considered to belong to the father and his clan. For this reason, when Europeans or American men took wives from such tribes, their children were considered "white" like their fathers, or "half-breeds". Generally such children could have no official place in the tribe because their fathers did not belong to it, unless they were adopted by a male and made part of his family.

In most of the Plains Nations, men traditionally hunt, trade and go to war. The women have traditionally held primary responsibility for the survival and welfare of the families (and future of the tribe). Traditionally, Plains women own the home, and tend to jobs such as gathering and cultivating plants for food and healing, along with caring for the young and the elderly, making clothing and processing and curing meat and skins. Plains women have historically tanned hides to make clothing as well as bags, saddle cloths, and tipi covers, and have used cradleboards to carry an infant while working or traveling.

Several dozen tribes have been documented to practiced polygyny to sisters, with procedural and economic limits.

Apart from making homes, women have traditionally held many additional responsibilities essential for the survival of the tribes, including the manufacture of weapons and tools, maintenance of the roofs of their homes, as well as participating in the bison hunts. In some of the Plains Indian tribes, medicine women gathered herbs and cured the ill.

The Lakota, Dakota, and Nakota girls have traditionally been encouraged to learn to ride, hunt and fight. Though fighting was predominantly the duty of men and boys, occasionally women fought as well, especially if the tribe was severely threatened.

Sports

Jim Thorpe was called the "greatest athlete in the world" by king Gustaf V of Sweden

Native American leisure time led to competitive individual and team sports. Jim Thorpe, Joe Hipp, Notah Begay III, Jacoby Ellsbury, and Billy Mills are well known professional athletes.

Ball players from the Choctaw and Lakota tribe as painted by George Catlin in the 1830s

Team based

Native American ball sports, sometimes referred to as lacrosse, stickball, or baggataway, was often used to settle disputes, rather than going to war, as a civil way to settle potential conflict. The Choctaw called it isitoboli ("Little Brother of War"); the Onondaga name was dehuntshigwa'es ("men hit a rounded object"). There are three basic versions, classified as Great Lakes, Iroquoian, and Southern.

The game is played with one or two rackets/sticks and one ball. The object of the game is to land the ball on the opposing team's goal (either a single post or net) to score and to prevent the opposing team from scoring on your goal. The game involves as few as 20 or as many as 300 players with no height or weight restrictions and no protective gear. The goals could be from around 200 feet (61 m) apart to about 2 miles (3.2 km); in Lacrosse the field is 110 yards (100 m).

Individual

Chunkey was a game that consisted of a disk shaped stone that was about 1–2 inches in diameter. The disk was thrown down a 200-foot (61 m) corridor so that it could roll past the players at great speed. The disk would roll down the corridor, and players would throw wooden shafts at the moving disk. The object of the game was to strike the disk or prevent your opponents from hitting it.

Music

Jake Fragua, Jemez Pueblo from New Mexico

Native American musicians have occasionally found broader fame in more mainstream American music. Artists such as Robbie Robertson (The Band), Buffy Sainte-Marie, and Redbone have had success on the rock and pop charts. Some, such as Sainte-Marie, John Trudell, and Blackfoot have used music as political commentary and part of their work as activists for Native American and First Nations causes. Others, such as flautists Charles Littleleaf record traditional instruments with an aim of preserving the sounds of nature, or in the case of R. Carlos Nakai, integrate traditional instruments with more modern instrumentation. A variety of small and medium-sized recording companies offer an abundance of contemporary music by Native Americans and descendants, ranging from pow-wow drum music to rock-and-roll and rap.

A popular Native American musical form is pow wow drumming and singing, which happens at events like the annual Gathering of Nations in Albuquerque, New Mexico. One form involves members of drum groups sitting in a circle around a large drum, playing in unison while they sing together in their Indigenous language. Often they are accompanied by dancers in colorful regalia. Most Indigenous communities in the United States also maintain private, traditional songs and ceremonies, which are only shared within the community.

Art

Drawings of kachina dolls, from an 1894 anthropology book.

Writing and communication

Sequoyah, inventor of the Cherokee syllabary

Native Americans in the United States have developed several original systems of communication, both in Pre-Columbian times, and later as a response to European influences. For example, the Iroquois, living around the Great Lakes and extending east and north, used strings or belts called wampum that served a dual function: the knots and beaded designs mnemonically chronicled tribal stories and legends, and further served as a medium of exchange and a unit of measure. The keepers of the articles were seen as tribal dignitaries. Another form of communication was the Wiigwaasabak, birch bark scrolls on which the Ojibwa (Anishinaabe) people wrote complex geometrical patterns and shapes, can also be considered a form of writing.

A widely used form of communication was Plains Indian Sign Language (PISL), also known as Plains Sign Talk, Plains Sign Language and First Nation Sign Language. PISL is a trade language (or international auxiliary language), formerly a trade pidgin, that was once the lingua franca across central Canada, central and western United States and northern Mexico, used among the various Plains Nations. It was also used for story-telling, oratory, various ceremonies, and by deaf people for ordinary daily use.

In the late 1810s and early 1820s, the Cherokee syllabary was invented by the silversmith Sequoyah to write the Cherokee language. His creation of the syllabary is particularly noteworthy as he could not previously read any script. He first experimented with logograms, before developing his system into a syllabary. In his system, each symbol represents a syllable rather than a single phoneme; the 85 (originally 86) characters provide a suitable method to write Cherokee. Although some symbols resemble Latin, Greek, and Cyrillic letters, the relationship between symbols and sounds is different.

The success of the Cherokee syllabary inspired James Evans, a missionary in what is now Manitoba, during the 1840s to develop Cree syllabics. Evans had originally adapted the Latin script to Ojibwe (see Evans system), but after learning of the Cherokee syllabary, he experimented with invented scripts based on his familiarity with shorthand and Devanagari. When Evans later worked with the closely related Cree, and ran into trouble with the Latin alphabet, he turned to his Ojibwe project and in 1840 adapted it to the Cree language. The result contained just nine glyph shapes, each of which stood for a syllable with the vowels determined by the orientations of these shapes. Cree syllabics are primarily a Canadian phenomenon, but are used occasionally in the United States by communities that straddle the border.

Interracial relations

Interracial relations between Native Americans, Europeans, and Africans is a complex issue that has been mostly neglected with "few in-depth studies on interracial relationships". Some of the first documented cases of European/Native American intermarriage and contact were recorded in Post-Columbian Mexico. One case is that of Gonzalo Guerrero, a European from Spain, who was shipwrecked along the Yucatan Peninsula, and fathered three Mestizo children with a Mayan noblewoman. Another is the case of Hernán Cortés and his mistress La Malinche, who gave birth to another of the first multi-racial people in the Americas.

Assimilation

European impact was immediate, widespread, and profound—more than any other race that had contact with Native Americans during the early years of colonization and nationhood. Europeans living among Native Americans were often called "White Indians". They "lived in native communities for years, learned native languages fluently, attended native councils, and often fought alongside their native companions."

Early contact was often charged with tension and emotion, but also had moments of friendship, cooperation, and intimacy. Marriages took place in English, Spanish, and French colonies between Native Americans and Europeans. Given the preponderance of men among the colonists in the early years, generally European men married American Indian women.

Charles Eastman was one of the first Native Americans to become certified as a medical doctor, after he graduated from Boston University.

There was fear on both sides, as the different peoples realized how different their societies were. The whites regarded the Indians as "savage" because they were not Christian. They were suspicious of cultures which they did not understand. The Native American author, Andrew J. Blackbird, wrote in his History of the Ottawa and Chippewa Indians of Michigan, (1897), that white settlers introduced some immoralities into Native American tribes. Many Indians suffered because the Europeans introduced alcohol and the whiskey trade resulted in alcoholism among the people, who were alcohol-intolerant.

As European-American women started working independently at missions and Indian schools in the western states, there were more opportunities for their meeting and developing relationships with Native American men. For instance, Charles Eastman, a man of European and Lakota descent whose father sent both his sons to Dartmouth College, got his medical degree at Boston University and returned to the West to practice. He married Elaine Goodale, whom he met in South Dakota. He was the grandson of Seth Eastman, a military officer from Maine, and a chief's daughter. Goodale was a young European-American teacher from Massachusetts and a reformer, who was appointed as the US superintendent of Native American education for the reservations in the Dakota Territory. They had six children together.

Slavery

The majority of Native American tribes did practice some form of slavery before the European introduction of African slavery into North America, but none exploited slave labor on a large scale. In addition, Native Americans did not buy and sell captives in the pre-colonial era, although they sometimes exchanged enslaved individuals with other tribes in peace gestures or in exchange for their own members.

The conditions of enslaved Native Americans varied among the tribes. In many cases, young enslaved captives were adopted into the tribes to replace warriors killed during warfare or by disease. Other tribes practiced debt slavery or imposed slavery on tribal members who had committed crimes; but, this status was only temporary as the enslaved worked off their obligations to the tribal society.

Among some Pacific Northwest tribes, about a quarter of the population were slaves. Other slave-owning tribes of North America were, for example, Comanche of Texas, Creek of Georgia, the Pawnee, and Klamath. There was heavily incentive by Europeans as a way of driving deeper wedges between Africans and Europeans as the Seminole Confederation had proved formidable. Slaveholding societies, like the Choctaw, were given highest privilege and respect amongst the Europeans and trade preference.

European enslavement

During the European colonization of North America, Native Americans changed their practice of slavery dramatically. Native Americans began selling war captives to white settlers rather than integrating them into their own societies as they had done before. As the demand for labor in the West Indies grew with the cultivation of sugar cane, European settlers frequently transported enslaved Native Americans to the Caribbean to work on plantations. White settlers in European colonies established in the American South purchased or captured Native Americans to use as forced labor in cultivating tobacco, rice, and indigo on plantations as well. Accurate records of the numbers enslaved do not exist. Scholars estimate tens of thousands of Native Americans may have been enslaved by the Europeans, sometimes being sold by Native Americans themselves but often war prizes with Europeans, similar to what occurred in the aftermath of the Pequot War.

Slavery in Colonial America soon became racialized, including Native Americans and Africans but excluding Europeans. The Virginia General Assembly defined some terms of slavery in 1705:

All servants imported and brought into the Country... who were not Christians in their native Country... shall be accounted and be slaves. All Negro, mulatto and Indian slaves within this dominion ... shall be held to be real estate. If any slave resists his master ... correcting such slave, and shall happen to be killed in such correction ... the master shall be free of all punishment ... as if such accident never happened.
— Virginia General Assembly declaration, 1705

The slave trade of Native Americans lasted only until around 1730. It gave rise to a series of devastating wars among the tribes, including the Yamasee War. The Indian Wars of the early 18th century, combined with the increasing importation of African slaves, effectively ended the Native American slave trade by 1750. Colonists found that Native American slaves could easily escape, as they knew the country. The wars cost the lives of numerous colonial slave traders and disrupted their early societies. The remaining Native American groups banded together to face the Europeans from a position of strength. Many surviving Native American peoples of the southeast strengthened their loose coalitions of language groups and joined confederacies such as the Choctaw, the Creek, and the Catawba for protection.

Native American women were at risk for rape whether they were enslaved or not; during the early colonial years, settlers were disproportionately male. They turned to Native women for sexual relationships. Both Native American and African enslaved women suffered rape and sexual harassment by male slaveholders and other white men.

Lillian Gross, described as a "Mixed Blood" by the Smithsonian source, was of Cherokee and European-American heritage. Raised within Cherokee culture, she identified with that.

Relation with Africans in the United States

African and Native Americans have interacted for centuries. The earliest record of Native American and African contact occurred in April 1502, when Spanish colonists transported the first Africans to Hispaniola to serve as slaves.

Buffalo Soldiers, 1890. The nickname was given to the "Black Cavalry" by the Native American tribes they fought.

Native Americans were rewarded if they returned escaped slaves, and African Americans were rewarded for fighting in the late 19th-century Indian Wars.

While numerous tribes used captive enemies as servants and slaves, they also often adopted younger captives into their tribes to replace members who had died. In the Southeast, a few Native American tribes began to adopt a slavery system similar to that of the American colonists, buying African American slaves, especially the Cherokee, Choctaw, and Creek. Though less than 3% of Native Americans owned slaves, divisions grew among the Native Americans over slavery. Among the Cherokee, records show that slave holders in the tribe were largely the children of European men that had shown their children the economics of slavery. As European colonists took slaves into frontier areas, there were more opportunities for relationships between African and Native American peoples.

Among the Five Civilized Tribes, mixed-race slaveholders were generally part of an elite hierarchy, often based on their mothers' clan status, as the societies had matrilineal systems. As did Benjamin Hawkins, European fur traders and colonial officials tended to marry high-status women, in strategic alliances seen to benefit both sides. The Choctaw, Creek and Cherokee believed they benefited from stronger alliances with the traders and their societies. The women's sons gained their status from their mother's families; they were part of hereditary leadership lines who exercised power and accumulated personal wealth in their changing Native American societies. The chiefs of the tribes believed that some of the new generation of mixed-race, bilingual chiefs would lead their people into the future and be better able to adapt to new conditions influenced by European Americans.

Philosophy

Native American authors have written about aspects of "tribal philosophy" as opposed to the modern or Western worldview. Thus, Yankton Dakota author Vine Deloria Jr. in an essay "Philosophy and the Tribal Peoples" argued that whereas a "traditional Westerner" might reason, "Man is mortal; Socrates is a man; therefore, Socrates is mortal," aboriginal thinking might read, 'Socrates is mortal, because I once met Socrates and he is a man like me, and I am mortal.' Deloria explains that both of the statements assume that all men are mortal, and that these statements are not verifiable on these grounds. The line of Indian thinking, however uses empirical evidence through memory to verify that Socrates was in fact a man like the person originally making the statement, and enhances the validity of the thinking. Deloria made the distinction, "whereas the Western syllogism simply introduces a doctrine using general concepts and depends on faith in the chain of reasoning for its verification, the Indian statement would stand by itself without faith and belief." Deloria also comments that Native American thinking is very specific (in the way described above) compared to the broadness of traditional Western thinking, which leads to different interpretations of basic principles. American thinkers have previously denounced Native ideas because of this narrower approach, as it leads to 'blurry' distinctions between the 'real' and the 'internal.'

According to Carlin Romano, the best resource on a characteristically "Native American Philosophy" is Scott L. Pratt's, Native Pragmatism: Rethinking the Roots of American Philosophy, which relates the ideas of many 'American' philosophers like Pierce, James, and Dewey to important concepts in early Native thought. Pratt's publication takes his readers on a journey through American philosophical history from the colonial time period, and via detailed analysis, connects the experimental nature of early American pragmatism to the empirical habit of indigenous Americans. Though Pratt makes these alliances very comprehensible, he also makes clear that the lines between the ideas of Native Americans and American philosophers are complex and historically difficult to trace.

Sunday, August 14, 2022

Residual-current device

From Wikipedia, the free encyclopedia

https://en.wikipedia.org/wiki/Residual-current_device

Typical GFCI receptacle found in North America

A residual-current device (RCD), residual-current circuit breaker (RCCB) or ground fault circuit interrupter (GFCI) is an electrical safety device that quickly breaks an electrical circuit with leakage current to ground. It is to protect equipment and to reduce the risk of serious harm from an ongoing electric shock. Injury may still occur in some cases, for example if a human receives a brief shock before the electrical circuit is isolated, falls after receiving a shock, or if the person touches both conductors at the same time.

If the RCD device has additional overcurrent protection integrated in the same device, it is referred to as RCBO. An earth leakage circuit breaker may be a RCD, although an older type of voltage-operated earth leakage circuit breaker (ELCB) also exists.

These electrical wiring devices are designed to quickly and automatically isolate a circuit when it detects that the electric current is unbalanced between the supply and return conductors of a circuit. Any difference between the currents in these conductors indicates leakage current, which presents a shock hazard. Alternating 60 Hz current above 20 mA (0.020 amperes) through the human body is potentially sufficient to cause cardiac arrest or serious harm if it persists for more than a small fraction of a second. RCDs are designed to disconnect the conducting wires ("trip") quickly enough to potentially prevent serious injury to humans, and to prevent damage to electrical devices.

RCDs are testable and resettable devices—a test button safely creates a small leakage condition, and another button resets the conductors after a fault condition has been cleared. Some RCDs disconnect both the energized and return conductors upon a fault (double pole), while a single pole RCD only disconnects the energized conductor. If the fault has left the return wire "floating" or not at its expected ground potential for any reason, then a single-pole RCD will leave this conductor still connected to the circuit when it detects the fault.

A two-pole, or double-pole, residual-current device. The test button and connect/disconnect switch are colored blue. A fault will trigger the switch to its down (off) position, which in this device would disconnect both conductors.
Log-log graph of the effect of alternating current I of duration T passing from left hand to feet as defined in IEC 60479-1.
1: Electromagnet with help electronics
2: Current transformer secondary winding
3: Transformer core
4: Test push-button
L: Line conductor
N: Neutral conductor

Purpose and operation

RCDs are designed to disconnect the circuit if there is a leakage current. In their first implementation in the 1950s, power companies used them to prevent electricity theft where consumers grounded returning circuits rather than connecting them to neutral to inhibit electrical meters from registering their power consumption.

The most common modern application is as a safety device to detect small leakage currents (typically 5–30 mA) and disconnecting quickly enough (<30 milliseconds) to prevent device damage or electrocution. They are an essential part of the automatic disconnection of supply (ADS), i.e. to switch off when a fault develops, rather than rely on human intervention, one of the essential tenets of modern electrical practice.

To reduce the risk of electrocution, RCDs should operate within 25–40 milliseconds with any leakage currents (through a person) of greater than 30 mA, before electric shock can drive the heart into ventricular fibrillation, the most common cause of death through electric shock. By contrast, conventional circuit breakers or fuses only break the circuit when the total current is excessive (which may be thousands of times the leakage current an RCD responds to). A small leakage current, such as through a person, can be a very serious fault, but would probably not increase the total current enough for a fuse or overload circuit breaker to isolate the circuit, and not fast enough to save a life.

RCDs operate by measuring the current balance between two conductors using a differential current transformer. This measures the difference between current flowing through the live conductor and that returning through the neutral conductor. If these do not sum to zero, there is a leakage of current to somewhere else (to earth/ground or to another circuit), and the device will open its contacts. Operation does not require a fault current to return through the earth wire in the installation; the trip will operate just as well if the return path is through plumbing, contact with the ground or any other current path. Automatic disconnection and a measure of shock protection is therefore still provided even if the earth wiring of the installation is damaged or incomplete.

For an RCD used with three-phase power, all three live conductors and the neutral (if fitted) must pass through the current transformer.

Application

Electrical plugs with incorporated RCD are sometimes installed on appliances that might be considered to pose a particular safety hazard, for example long extension leads, which might be used outdoors, or garden equipment or hair dryers, which may be used near a bath or sink. Occasionally an in-line RCD may be used to serve a similar function to one in a plug. By putting the RCD in the extension lead, protection is provided at whatever outlet is used even if the building has old wiring, such as knob and tube, or wiring that does not contain a grounding conductor. The in-line RCD can also have a lower tripping threshold than the building to further improve safety for a specific electrical device.

In North America, GFI receptacles can be used in cases where there is no grounding conductor, but they must be labeled as "no equipment ground". This is referenced in the National Electric Code section 406 (D) 2, however codes change and someone should always consult a licensed professional and their local building and safety departments. The code is An ungrounded GFI receptacle will trip using the built-in "test" button, but will not trip using a GFI test plug, because the plug tests by passing a small current from line to the non-existent ground. It is worth noting that despite this, only one GFCI receptacle at the beginning of each circuit is necessary to protect downstream receptacles. There does not appear to be a risk of using multiple GFI receptacles on the same circuit, though it is considered redundant.

In Europe, RCDs can fit on the same DIN rail as the miniature circuit breakers; much like in miniature circuit breakers, the busbar arrangements in consumer units and distribution boards provides protection for anything downstream.

RCBO

A pure RCD will detect imbalance in the currents of the supply and return conductors of a circuit. But it cannot protect against overload or short circuit like a fuse or a miniature circuit breaker (MCB) does (except for the special case of a short circuit from live to ground, not live to neutral).

However, a RCD and a MCB often come integrated in the same device, thus being able to detect both supply imbalance and overload current. Such a device is called

RCBO (for residual-current circuit breaker with overcurrent protection) in Europe and Australia;
GFCI breaker (for ground fault circuit interrupter) in USA and Canada;

Typical design

Internal mechanism of RCD

Opened 3-phase residual-current device

The diagram depicts the internal mechanism of a residual-current device (RCD). The device is designed to be wired in-line in an appliance power cord. It is rated to carry a maximal current of 13 A and is designed to trip on a leakage current of 30 mA. This is an active RCD; that is, it latches electrically and therefore trips on power failure, a useful feature for equipment that could be dangerous on unexpected re-energisation. Some early RCDs were entirely electromechanical and relied on finely balanced sprung over-centre mechanisms driven directly from the current transformer. As these are hard to manufacture to the required accuracy and prone to drift in sensitivity both from pivot wear and lubricant dry-out, the electronically-amplified type with a more robust solenoid part as illustrated are now dominant.

In the internal mechanism of an RCD, the incoming supply and the neutral conductors are connected to the terminals at (1), and the outgoing load conductors are connected to the terminals at (2). The earth conductor (not shown) is connected through from supply to load uninterrupted. When the reset button (3) is pressed, the contacts ((4) and another, hidden behind (5)) close, allowing current to pass. The solenoid (5) keeps the contacts closed when the reset button is released.

The sense coil (6) is a differential current transformer which surrounds (but is not electrically connected to) the live and neutral conductors. In normal operation, all the current down the live conductor returns up the neutral conductor. The currents in the two conductors are therefore equal and opposite and cancel each other out.

Any fault to earth (for example caused by a person touching a live component in the attached appliance) causes some of the current to take a different return path, which means that there is an imbalance (difference) in the current in the two conductors (single-phase case), or, more generally, a nonzero sum of currents from among various conductors (for example, three phase conductors and one neutral conductor).

This difference causes a current in the sense coil (6), which is picked up by the sense circuitry (7). The sense circuitry then removes power from the solenoid (5), and the contacts (4) are forced apart by a spring, cutting off the electricity supply to the appliance. A power failure will also remove power from the solenoid and cause the contacts to open, causing the safe trip-on-power-failure behaviour mentioned above.

The test button (8) allows the correct operation of the device to be verified by passing a small current through the orange test wire (9). This simulates a fault by creating an imbalance in the sense coil. If the RCD does not trip when this button is pressed, then the device must be replaced.

RCD with additional overcurrent protection circuitry (RCBO or GFCI breaker)

An example of a rail-mounted RCBO

Residual-current and over-current protection may be combined in one device for installation into the service panel; this device is known as a GFCI (Ground-Fault Circuit Interrupter) breaker in the US and Canada, and as a RCBO (residual-current circuit breaker with over-current protection) in Europe and Australia. They are effectively a combination of a RCD and a MCB. In the US, GFCI breakers are more expensive than GFCI outlets.

As well as requiring both live and neutral inputs and outputs (or, full three-phase), many GFCI/RCBO devices require a functional earth (FE) connection. This serves to provide both EMC immunity and to reliably operate the device if the input-side neutral connection is lost but live and earth remain.

For reasons of space, many devices, especially in DIN rail format, use flying leads rather than screw terminals, especially for the neutral input and FE connections. Additionally, because of the small form factor, the output cables of some models (Eaton/MEM) are used to form the primary winding of the RCD part, and the outgoing circuit cables must be led through a specially dimensioned terminal tunnel with the current transformer part around it. This can lead to incorrect failed trip results when testing with meter probes from the screw heads of the terminals, rather than from the final circuit wiring.

Having one RCD feeding another is generally unnecessary, provided they have been wired properly. One exception is the case of a TT earthing system, where the earth loop impedance may be high, meaning that a ground fault might not cause sufficient current to trip an ordinary circuit breaker or fuse. In this case a special 100 mA (or greater) trip current time-delayed RCD is installed, covering the whole installation, and then more sensitive RCDs should be installed downstream of it for sockets and other circuits that are considered high-risk.

RCD with additional arc fault protection circuitry

In addition to ground fault circuit interrupters (GFCIs), arc-fault circuit interrupters (AFCI) are equally important as they offer added protection from potentially hazardous arc-faults resulting from damage in branch circuit wiring as well as extensions to branches such as appliances and cord sets. By detecting hazardous arc-faults and responding by interrupting power, AFCIs helps reduce the likelihood of the home's electrical system being an ignition source of a fire. Dual function AFCI/GFCI devices offer both electrical fire prevention and shock prevention in one device making them a solution for many rooms in the home, especially when replacing an existing standard receptacle or existing ungrounded receptacle.

Common features and variations

Differences in disconnection actions

Major differences exist regarding the manner in which an RCD-unit will act to disconnect the power to a circuit or appliance.

There are four situations in which different types of RCD-units are used:

At the consumer power distribution level, usually in conjunction with an RCBO resettable circuit breaker;
Built into a wall socket;
Plugged into a wall socket, which may be part of a power-extension cable; and
Built into the cord of a portable appliance, such as those intended to be used in outdoor or wet areas.

The first three of those situations, relate largely to usage as part of a power-distribution system and are almost always of the 'passive' or 'latched' variety, whereas the fourth relates solely to specific appliances and are always of the 'active' or 'non-latching' variety. 'Active' means prevention of any 're-activation' of the power supply after any inadvertent form of power outage, as soon as the mains supply becomes re-established; 'latch' relates to a 'switch' inside the unit housing the RCD that remains as set following any form of power outage, but has to be reset manually after the detection of an error-condition.

In the fourth situation, it would be deemed to be highly undesirable, and probably very unsafe, for a connected appliance to automatically resume operation after a power disconnection, without having the operator in attendance – as such manual reactivation of the RCD is necessary.

The difference between the modes of operation of the essentially two different types of RCD functionality is that the operation for power distribution purposes requires the internal latch to remain set within the RCD after any form of power disconnection caused by either the user turning the power off, or after any power outage; such arrangements are particularly applicable for connections to refrigerators and freezers.

Situation two is mostly installed just as described above, but some wall socket RCDs are available to fit the fourth situation, often by operating a switch on the fascia panel.

RCDs for the first and third situation are most commonly rated at 30 mA and 40 ms. For the fourth situation, there is generally a greater choice of ratings available – generally all lower than the other forms, but lower values often result in more nuisance tripping. Sometimes users apply protection in addition to one of the other forms, when they wish to override those with a lower rating. It may be wise to have a selection of type 4 RCDs available, because connections made under damp conditions or using lengthy power cables are more prone to trip-out when any of the lower ratings of RCD are used; ratings as low as 10 mA are available.

Number of poles and pole terminology

The number of poles represents the number of conductors that are interrupted when a fault condition occurs. RCDs used on single-phase AC supplies (two current paths), such as domestic power, are usually one- or two-pole designs, also known as single- and double-pole. A single-pole RCD interrupts only the energized conductor, while a double-pole RCD interrupts both the energized and return conductors. (In a single-pole RCD, the return conductor is usually anticipated to be at ground potential at all times and therefore safe on its own).

RCDs with three or more poles can be used on three-phase AC supplies (three current paths) or to disconnect an earth conductor as well, with four-pole RCDs used to interrupt three-phase and neutral supplies. Specially designed RCDs can also be used with both AC and DC power distribution systems.

The following terms are sometimes used to describe the manner in which conductors are connected and disconnected by an RCD:

Single-pole or one-pole – the RCD will disconnect the energized wire only.
Double-pole or two-pole – the RCD will disconnect both the energized and return wires.
1+N and 1P+N – non-standard terms used in the context of RCBOs, at times used differently by different manufacturers. Typically these terms may signify that the return (neutral) conductor is an isolating pole only, without a protective element (an unprotected but switched neutral), that the RCBO provides a conducting path and connectors for the return (neutral) conductor but this path remains uninterrupted when a fault occurs (sometimes known as "solid neutral"), or that both conductors are disconnected for some faults (such as RCD detected leakage) but only one conductor is disconnected for other faults (such as overload).

Sensitivity

RCD sensitivity is expressed as the rated residual operating current, noted I_Δn. Preferred values have been defined by the IEC, thus making it possible to divide RCDs into three groups according to their I_Δn value:

high sensitivity (HS): 5** – 10 – 30 mA (for direct-contact or life injury protection),
medium sensitivity (MS): 100 – 300 – 500 – 1000 mA (for fire protection),
low sensitivity (LS): 3 – 10 – 30 A (typically for protection of machine).

The 5 mA sensitivity is typical for GFCI outlets.

Break time (response speed)

There are two groups of devices. G (general use) instantaneous RCDs have no intentional time delay. They must never trip at one-half of the nominal current rating, but must trip within 200 milliseconds for rated current, and within 40 milliseconds at five times rated current. S (selective) or T (time-delayed) RCDs have a short time delay. They are typically used at the origin of an installation for fire protection to discriminate with G devices at the loads, and in circuits containing surge suppressors. They must not trip at one-half of rated current. They provide at least 130 milliseconds delay of tripping at rated current, 60 milliseconds at twice rated, and 50 milliseconds at five times rated. The maximum break time is 500 ms at rated current, 200 ms at twice rated, and 150 ms at five times rated.

Programmable earth fault relays are available to allow co-ordinated installations to minimise outage. For example, a power distribution system might have a 300 mA, 300 ms device at the service entry of a building, feeding several 100 mA S type at each sub-board, and 30 mA G type for each final circuit. In this way, a failure of a device to detect the fault will eventually be cleared by a higher-level device, at the cost of interrupting more circuits.

Type, or mode (types of current leakage issue detected)

IEC Standard 60755 (General requirements for residual current operated protective devices) defines three types of RCD depending on the waveforms and frequency of the fault current.

Type AC RCDs trip on sinusoidal residual current.
Type A RCDs, in addition to Type AC, also respond to pulsating or continuous direct current of either polarity.
Type B RCDs, in addition to Type A, also respond to steady DC, and higher frequency current, or for combinations of alternating and direct current as may be found from single-phase or multi-phase rectifying circuits, like all the switching power supplies used at home, or for example washing machines etc., equipped with DC motors.

The BEAMA RCD Handbook - Guide to the Selection and Application of RCDs summaries this as follows:

Type AC RCDs trip on alternating sinusoidal residual current, suddenly applied or smoothly increasing.
Type A RCDs trip on alternating sinusoidal residual current and on residual pulsating direct current, suddenly applied or smoothly increasing.
Type F RCDs trip in the same conditions as Type A and in addition:
- for composite residual currents, whether suddenly applied or slowly rising intended for circuit supplied between phase and neutral or phase and earthed middle conductor;
- for residual pulsating direct currents superimposed on smooth direct current.
Type B RCDs trip in the same conditions as Type F and in addition:
- for residual sinusoidal alternating currents up to 1 kHz;
- for residual alternating currents superimposed on a smooth direct current;
- for residual pulsating direct currents superimposed on a smooth direct current;
- for residual pulsating rectified direct current which results from two or more phases;
- for residual smooth direct currents whether suddenly applied or slowly increased independent of polarity.

and notes that these designations have been introduced because some designs of type A and AC RCD can be disabled if a DC current is present that saturates the core of the detector.

Surge current resistance

The surge current refers to the peak current an RCD is designed to withstand using a test impulse of specified characteristics. The IEC 61008 and IEC 61009 standards require that RCDs withstand a 200 A "ring wave" impulse. The standards also require RCDs classified as "selective" to withstand a 3000 A impulse surge current of specified waveform.

Testing of correct operation

Test button

RCDs can be tested with a built-in test button to confirm functionality on a regular basis. RCDs may not operate correctly if wired improperly, so they are generally tested by the installer to verify correct operation. Use of a multifunction tester in the EU or a solenoid voltmeter in the USA. This introduces a controlled fault current from live to earth and measures the RCD operating time. This tests if the device is operational and can test the wiring to the RCD. Such a test may be performed on installation of the device and at any "downstream" outlet. (Upstream outlets are not protected.) To avoid needless tripping, only one RCD should be installed on any single circuit (excluding corded RCDs, such as bathroom small appliances).

Limitations

A residual-current circuit breaker cannot remove all risk of electric shock or fire. In particular, an RCD alone will not detect overload conditions, phase-to-neutral short circuits or phase-to-phase short circuits (see three-phase electric power). Over-current protection (fuses or circuit breakers) must be provided. Circuit breakers that combine the functions of an RCD with overcurrent protection respond to both types of fault. These are known as RCBOs and are available in 2-, 3- and 4-pole configurations. RCBOs will typically have separate circuits for detecting current imbalance and for overload current but use a common interrupting mechanism.

An RCD helps to protect against electric shock when current flows through a person from a phase (live / line / hot) to earth. It cannot protect against electric shock when current flows through a person from phase to neutral or from phase to phase, for example where a finger touches both live and neutral contacts in a light fitting; a device cannot differentiate between current flow through an intended load from flow through a person, though the RCD may still trip if the person is in contact with the ground (earth), as some current may still pass through the persons finger and body to earth.

Whole installations on a single RCD, common in older installations in the UK, are prone to "nuisance" trips that can cause secondary safety problems with loss of lighting and defrosting of food. Frequently the trips are caused by deteriorating insulation on heater elements, such as water heaters and cooker elements or rings. Although regarded as a nuisance, the fault is with the deteriorated element and not the RCD: replacement of the offending element will resolve the problem, but replacing the RCD will not.

In the case of RCDs that need a power supply, a dangerous condition can arise if the neutral wire is broken or switched off on the supply side of the RCD, while the corresponding live wire remains uninterrupted. The tripping circuit needs power to work and does not trip when the power supply fails. Connected equipment will not work without a neutral, but the RCD cannot protect people from contact with the energized wire. For this reason circuit breakers must be installed in a way that ensures that the neutral wire cannot be switched off unless the live wire is also switched off at the same time. Where there is a requirement for switching off the neutral wire, two-pole breakers (or four-pole for 3-phase) must be used. To provide some protection with an interrupted neutral, some RCDs and RCBOs are equipped with an auxiliary connection wire that must be connected to the earth busbar of the distribution board. This either enables the device to detect the missing neutral of the supply, causing the device to trip, or provides an alternative supply path for the tripping circuitry, enabling it to continue to function normally in the absence of the supply neutral.

Related to this, a single-pole RCD/RCBO interrupts the energized conductor only, while a double-pole device interrupts both the energized and return conductors. Usually this is a standard and safe practice, since the return conductor is held at ground potential anyway. However, because of its design, a single-pole RCD will not isolate or disconnect all relevant wires in certain uncommon situations, for example where the return conductor is not being held, as expected, at ground potential, or where current leakage occurs between the return and earth conductors. In these cases, a double-pole RCD will offer protection, since the return conductor would also be disconnected.

History and nomenclature

The world's first high-sensitivity earth leakage protection system (i.e. a system capable of protecting people from the hazards of direct contact between a live conductor and earth), was a second-harmonic magnetic amplifier core-balance system, known as the magamp, developed in South Africa by Henri Rubin. Electrical hazards were of great concern in South African gold mines, and Rubin, an engineer at the company C.J. Fuchs Electrical Industries of Alberton Johannesburg, initially developed a cold-cathode system in 1955 which operated at 525 V and had a tripping sensitivity of 250 mA. Prior to this, core balance earth leakage protection systems operated at sensitivities of about 10 A.

The cold cathode system was installed in a number of gold mines and worked reliably. However, Rubin began working on a completely novel system with greatly improved sensitivity, and by early 1956, he had produced a prototype second-harmonic magnetic amplifier-type core balance system (South African Patent No. 2268/56 and Australian Patent No. 218360). The prototype magamp was rated at 220 V, 60 A and had an internally adjustable tripping sensitivity of 12.5–17.5 mA. Very rapid tripping times were achieved through a novel design, and this combined with the high sensitivity was well within the safe current-time envelope for ventricular fibrillation determined by Charles Dalziel of the University of California, Berkeley, USA, who had estimated electrical shock hazards in humans. This system, with its associated circuit breaker, included overcurrent and short-circuit protection. In addition, the original prototype was able to trip at a lower sensitivity in the presence of an interrupted neutral, thus protecting against an important cause of electrical fire.

Following the accidental electrocution of a woman in a domestic accident at the Stilfontein gold mining village near Johannesburg, a few hundred F.W.J. 20 mA magamp earth leakage protection units were installed in the homes of the mining village during 1957 and 1958. F.W.J. Electrical Industries, which later changed its name to FW Electrical Industries, continued to manufacture 20 mA single phase and three phase magamp units.

At the time that he worked on the magamp, Rubin also considered using transistors in this application, but concluded that the early transistors then available were too unreliable. However, with the advent of improved transistors, the company that he worked for and other companies later produced transistorized versions of earth leakage protection.

In 1961, Dalziel, working with Rucker Manufacturing Co., developed a transistorized device for earth leakage protection which became known as a Ground Fault Circuit Interrupter (GFCI), sometimes colloquially shortened to Ground Fault Interrupter (GFI). This name for high-sensitivity earth leakage protection is still in common use in the U.S.A.

In the early 1970s most North American GFCI devices were of the circuit breaker type. GFCIs built into the outlet receptacle became commonplace beginning in the 1980s. The circuit breaker type, installed into a distribution panel, suffered from accidental trips mainly caused by poor or inconsistent insulation on the wiring. False trips were frequent when insulation problems were compounded by long circuit lengths. So much current leaked along the length of the conductors' insulation that the breaker might trip with the slightest increase of current imbalance. The migration to outlet receptacle based protection in North American installations reduced the accidental trips and provided obvious verification that wet areas were under electrical code-required protection. European installations continue to use primarily RCDs installed at the distribution board, which provides protection in case of damage to fixed wiring; In Europe socket-based RCDs are primarily used for retrofitting.

Regulation and adoption

Regulations differ widely from country to country. A single RCD installed for an entire electrical installation provides protection against shock hazards to all circuits, however, any fault may cut all power to the premises. A solution is to create groups of circuits each with a RCD, or to use RCBO for each individual circuit.

Australia

In Australia, residual current devices have been mandatory on power circuits since 1991 and on light circuits since 2000. A minimum of two RCDs is required per domestic installation. All socket outlets and lighting circuits are to be distributed over circuit RCDs. A maximum of three subcircuits only, may be connected to a single RCD.

Austria

Austria regulated residual current devices in the ÖVE E8001-1/A1:2013-11-01 norm (most recent revision). It has been required in private housing since 1980. The maximum activation time must not exceed 0.4 seconds. It needs to be installed on all circuits with power plugs with a maximum leakage current of 30 mA and a maximum rated current of 16 A.

Additional requirements are placed on circuits in wet areas, construction sites and commercial buildings.

Belgium

Belgian domestic installations are required to be equipped with a 300 mA residual current device that protects all circuits. Furthermore, at least one 30 mA residual current device is required that protects all circuits in "wet rooms" (e.g. bathroom, kitchen) as well as circuits that power certain "wet" appliances (washing machine, tumble dryer, dishwasher). Electrical underfloor heating is required to be protected by a 100 mA RCD. These RCDs must be of type A.

Brazil

Since NBR 5410 (1997) residual current devices and grounding are required for new construction or repair in wet areas, outdoor areas, interior outlets used for external appliances, or in areas where water is more probable like bathrooms and kitchens.

Denmark

Denmark requires 30 mA RCDs on all circuits that are rated for less than 20 A (circuits at greater rating are mostly used for distribution). RCDs became mandatory in 1975 for new buildings, and then for all buildings in 2008.

France

According to the NF C15-100 regulation (1911 -> 2002), a general RCD not exceeding 100 to 300 mA at the origin of the installation is mandatory. Moreover, in rooms where there is water, high power or sensitive equipment (bathrooms, kitchens, IT...), each socket outlet must be protected by an RCD not exceeding 30 mA. The type of RCD required (A, AC, F) depends upon the type of the equipment that will be connected and the maximum power of the socket outlet. Minimal distances between electrical devices and water or the floor are described and mandatory.

Germany

Since 1 May 1984, RCDs are mandatory for all rooms with a bath tub or a shower. Since June 2007 Germany requires the use of RCDs with a trip current of no more than 30 mA on sockets rated up to 32 A which are for general use. (DIN VDE 0100-410 Nr. 411.3.3). It isn't allowed to use type "AC" RCDs since 1987, to be used to protect humans against electrical shocks. It must be Type "A" or type "B".

India

According to Regulation 36 of the Electricity Regulations 1990

a) For a place of public entertainment, protection against earth leakage current must be provided by a residual current device of sensitivity not exceeding 10 mA.

b) For a place where the floor is likely to be wet or where the wall or enclosure is of low electrical resistance, protection against earth leakage current must be provided by a residual current device of sensitivity not exceeding 10 mA.

c) For an installation where hand-held equipment, apparatus or appliance is likely to be used, protection against earth leakage current must be provided by a residual current device of sensitivity not exceeding 30 mA.

d) For an installation other than the installation in (a), (b) and (c), protection against earth leakage current must be provided by a residual current device of sensitivity not exceeding 100 mA.

Italy

The Italian law (n. 46 March 1990) prescribes RCDs with no more than 30 mA residual current (informally called "salvavita"—life saver, after early BTicino models, or differential circuit breaker for the mode of operation) for all domestic installations to protect all the lines. The law was recently updated to mandate at least two separate RCDs for separate domestic circuits. Short-circuit and overload protection has been compulsory since 1968.

Malaysia

In the latest guidelines for electrical wiring in residential buildings (2008) handbook, the overall residential wiring need to be protected by a residual current device of sensitivity not exceeding 100 mA. Additionally, all power sockets need to be protected by a residual current device of sensitivity not exceeding 30 mA and all equipment in wet places (water heater, water pump) need to be protected by a residual current device of sensitivity not exceeding 10 mA.

New Zealand

From January 2003, all new circuits originating at the switchboard supplying lighting or socket outlets (power points) in domestic buildings must have RCD protection. Residential facilities (such as boarding houses, hospitals, hotels and motels) will also require RCD protection for all new circuits originating at the switchboard supplying socket outlets. These RCDs will normally be located at the switchboard. They will provide protection for all electrical wiring and appliances plugged into the new circuits.

North America

A Leviton GFCI "Decora" socket in a North American kitchen. Local electrical code requires tamper-resistant socket in homes, and requires a GFCI for socket within 1 metre of a sink. The T-slot indicates this device is rated 20 A and can take either a NEMA 5-15 or a NEMA 5-20 plug, though the latter type is rare on household appliances.

In North America socket-outlets located in places where an easy path to ground exists—such as wet areas and rooms with uncovered concrete floors—must be protected by a GFCI. The US National Electrical Code has required devices in certain locations to be protected by GFCIs since the 1960s. Beginning with underwater swimming pool lights (1968) successive editions of the code have expanded the areas where GFCIs are required to include: construction sites (1974), bathrooms and outdoor areas (1975), garages (1978), areas near hot tubs or spas (1981), hotel bathrooms (1984), kitchen counter sockets (1987), crawl spaces and unfinished basements (1990), near wet bar sinks (1993), near laundry sinks (2005) and in laundry rooms (2014).

GFCIs are commonly available as an integral part of a socket or a circuit breaker installed in the distribution panelboard. GFCI sockets invariably have rectangular faces and accept so-called Decora face plates, and can be mixed with regular outlets or switches in a multi-gang box with standard cover plates. In both Canada and the US older two-wire, ungrounded NEMA 1 sockets may be replaced with NEMA 5 sockets protected by a GFCI (integral with the socket or with the corresponding circuit breaker) in lieu of rewiring the entire circuit with a grounding conductor. In such cases the sockets must be labeled "no equipment ground" and "GFCI protected"; GFCI manufacturers typically provide tags for the appropriate installation description.

GFCIs approved for protection against electric shock trip at 5 mA within 25 ms. A GFCI device which protects equipment (not people) is allowed to trip as high as 30 mA of current; this is known as an Equipment Protective Device (EPD). RCDs with trip currents as high as 500 mA are sometimes deployed in environments (such as computing centers) where a lower threshold would carry an unacceptable risk of accidental trips. These high-current RCDs serve for equipment and fire protection instead of protection against the risks of electrical shocks.

In the United States the American Boat and Yacht Council requires both GFCIs for outlets and Equipment Leakage Circuit Interrupters (ELCI) for the entire boat. The difference is GFCIs trip on 5 mA of current whereas ELCIs trip on 30 mA after up to 100 ms. The greater values are intended to provide protection while minimizing nuisance trips.

Norway

In Norway, it has been required in all new homes since 2002, and on all new sockets since 2006. This applies to 32 A sockets and below. The RCD must trigger after a maximum 0.4 seconds for 230 V circuits, or 0.2 seconds for 400 V circuits.

South Africa

South Africa mandated the use of Earth Leakage Protection devices in residential environments (e.g. houses, flats, hotels, etc.) from October 1974, with regulations being refined in 1975 and 1976. Devices need to be installed in new premises and when repairs are carried out. Protection is required for power outlets and lighting, with the exception of emergency lighting that should not be interrupted. The standard device used in South Africa is indeed a hybrid of ELPD and RCCB.

Taiwan

Taiwan requires circuits of receptacles in washrooms, balconies, and receptacles in kitchen no more than 1.8 metres from the sink the use of earth leakage circuit breakers. This requirement also apply to circuit of water heater in washrooms and circuits that involves devices in water, lights on metal frames, public drinking fountains and so on. In principle, ELCBs should be installed on branch circuits, with trip current no more than 30 mA within 0.1 second according to Taiwanese law.

Turkey

Turkey requires the use of RCDs with no more than 30 mA and 300 mA in all new homes since 2004. This rule was introduced in RG-16/06/2004-25494.

United Kingdom

The current (18th) edition of the IEE Electrical Wiring Regulations requires that all socket outlets in most installations have RCD protection, though there are exemptions. Non armoured cables buried in walls must also be RCD protected (again with some specific exemptions). Provision of RCD protection for circuits present in bathrooms and shower rooms reduces the requirement for supplementary bonding in those locations. Two RCDs may be used to cover the installation, with upstairs and downstairs lighting and power circuits spread across both RCDs. When one RCD trips, power is maintained to at least one lighting and power circuit. Other arrangements, such as the use of RCBOs, may be employed to meet the regulations. The new requirements for RCDs do not affect most existing installations unless they are rewired, the distribution board is changed, a new circuit is installed, or alterations are made such as additional socket outlets or new cables buried in walls.

RCDs used for shock protection must be of the 'immediate' operation type (not time-delayed) and must have a residual current sensitivity of no greater than 30 mA.

If spurious tripping would cause a greater problem than the risk of the electrical accident the RCD is supposed to prevent (examples might be a supply to a critical factory process, or to life support equipment), RCDs may be omitted, providing affected circuits are clearly labelled and the balance of risks considered; this may include the provision of alternative safety measures.

The previous edition of the regulations required use of RCDs for socket outlets that were liable to be used by outdoor appliances. Normal practice in domestic installations was to use a single RCD to cover all the circuits requiring RCD protection (typically sockets and showers) but to have some circuits (typically lighting) not RCD protected. This was to avoid a potentially dangerous loss of lighting should the RCD trip. Protection arrangements for other circuits varied. To implement this arrangement it was common to install a consumer unit incorporating an RCD in what is known as a split load configuration, where one group of circuit breakers is supplied direct from the main switch (or time delay RCD in the case of a TT earth) and a second group of circuits is supplied via the RCD. This arrangement had the recognised problems that cumulative earth leakage currents from the normal operation of many items of equipment could cause spurious tripping of the RCD, and that tripping of the RCD would disconnect power from all the protected circuits.

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