ARE BS 15.3- electricity cont'd

The grounded and neutral conductors are necessary to complete an electrical circuit. They provide a continuous path from the load to ground.

Both conductors are connected to the earth, to ground, but there are differences in the location and function of each of these conductors.

A universal motor is a fractional horsepower, less then 1 hp, motor designed to operate on both alternating current and direct current power.

Universal motors are used on appliances such as blenders, vacuum cleaners, and power tools, such as routers and electric drills.

The 480, 277 V, alternating current, three phase, four wire system is a common electrical service in most medium and large modern commercial buildings.

480 V three-phase power is used to power specially designed heavy machinery. High voltage, 277 V fluorescent lighting and other single phase devices have also been developed specifically for use with this system.

A higher voltage means that a circuit can carry more current:

A 208 V current circuit can carry 1.73 times the current of a 120 V circuit, because 208 V divided by 120 V equals 1.73.

On a 120, 240 V system, a 120 V branch circuit provides electrical energy to convenience outlets, small appliances, and light fixtures.

A 240 V branch circuit serves large appliances and equipment, such as electric resistance baseboard heaters, water heaters, and air conditioning equipment.

A 240 V circuit can carry twice the current of a 120 V circuit

A 277 V circuit can carry 2.31 times the current of a 120 V circuit.

A single floor receptacle is drawn as a square with a circle inside it with a horizontal line running through it.

A duplex floor receptacle is Tron as a circle with two horizontal lines running through it, surrounded by a square.

Two general types of busway systems are feeder and plug-in.

A feeder busway is used to deliver large amounts of power with low voltage drop. A plug-in busway is used to provide power tap offs at multiple points.

A ground fault circuit interrupter is an electrical Device that detects and extremely low leak of electrical current, and act quickly to shut off power.

A ground fault circuit interrupt her is designed to protect the user of an electrical appliance much like a circuit breaker or fuse safeguards the wiring in an electrical system.

A ground fault is the unintentional flow of electric current between a power source, such as an ungrounded hot wire, and a grounded surface.

A ground fault occurs when electrical current leaks or is scapes to ground.

Ground fault protection, GFP, is designed to detect and rapidly interrupt low level equipment ground faults.

A ground fault protection device operates on the same principle as the ground fault circuit protection: by monitoring the current and quickly shutting off power When Current is not equal.

System grounding is that part of a building electrical system that provides protection against electrical shock, lightning, and fires.

A grounding system must be connected to an underground metal water, not gas pipe, in direct contact with the earth, for no less than 10 feet.

Locked motor amperage is the highest amperage that a motor polls.

A motor operating at it's rated speed, voltage, and horsepower, draws current at its full load amperage, or running load amperage.

The conductors served by a neutral must measure voltage between the ungrounded conductors, and be protected by a double or triple pole breaker, or set of fuses.

A neutral conductor cannot buy definition serve a single, 120 V circuit, because it has only one ungrounded conductor.

On a 120, 240 V, three wire service entrance, feed her, or branch circuit, there is a neutral conductor and two ungrounded hot conductors, each with 120 V to ground.

A neutral conductor is also present on 208, 120 V, and 480, 277 V services, theaters, and circuits.

Neutral conductor

A neutral conductor performs the function of a grounded conductor, for at least two ungrounded, hot conductors, that have sources from different voltage phases, such as on a multi wire branch circuit, multi wire feeder, and the electrical service.

With a grounding conductor connecting the appliance housing to ground, a faulty but complete circuit is created, and the circuit breaker or fuse protecting the circuit would open, thereby shutting down power to the faulty appliance, and eliminating occupant hazard.

A sensually, the grounding conductor provides an added safety feature to the wiring system.

A motors service factor indicates the percentage it can be continuously overloaded without developing damage related to overheating.

A service factor of 1.2 indicates that a motor can be continuously operated at 120% of its horsepower rating.

Grounded and neutral conductors should be wired so a circuit breaker, fuse, or switch does not interrupt them.

A switch or overcurrent device located in the grounded or neutral conductor allows the remainder of the circuit wiring to remain electrically hot if it opens the circuit.

At least two types of conductors are required to deliver alternating current in a building electrical system: the ungrounded conductor, and the neutral conductor.

A third conductor, called a grounding conductor, is added to most circuits.

When joining components to form a good bond, special connections called bonding jumpers may be required to ensure a good connection between the metal components.

Bonding jumpers are required in instances would flexible conduit is used.

Wire gutters or wire ways are sheet-metal or nonmetallic flame resistant troughs, that serve as housings that encloses and protects conductors.

Access to the enclosure interior is through a hinged door or removable cover. Wire gutters and wire ways typically carry large conductors.

Passive shielding can be accomplished by using a conductive sheet material, similar to a window screen, in front of the appliance or equipment. The shield must be connected to electrical ground for maximum efficiency.

Active shielding can be used to eliminate high levels of electromagnetic fields. Active shielding uses a system that since is the existence of a magnetic field, and generates a current on additional conductors such that it reduces, cancels the effects, of the magnetic field.

Equipment grounding conductor is a bear conductor, or a green colored insulated conductor, that connects, meaning bonds, the outlet boxes, metallic raceways, other enclosures and frames on motors, appliances, and other electrical equipment.

All receptacles must be of the grounding type, with supplementary grounding slot, and must be connected to the equipment grounding conductor.

Interruption of the grounded or neutral conductor with a circuit breaker, fuse, or switch, is considered poor practice. When switching control is desired in a circuit, the ungrounded hot wire should be the conductor that is switched.

Also, the circuit should be protected with a circuit breaker or fuse in the ungrounded hotwire, so that if a short circuit or current overload occurs, the entire circuit is interrupted.

Compared with the 208, 120 V system, a given conductor can carry twice the load, and the wire size for feeders can be quite significantly smaller.

Also, the smaller current at 480 V permits the use of protective devices with both smaller frame sizes and interrupting ratings.

Because ground fault circuit interrupt her's and arc volt circuit interrupters are extremely sensitive, they have a tendency to trip frequently. This repeated tripping is referred to as nuisance tripping.

Appliances that are beginning to fail can cause nuisance tripping, as well as lightning. For this reasoning, it is not recommended to connect essential equipment, such as refrigerators and freezers, into an outlet with ground fault or our fault circuit protection.

A safety Device called an arc fault circuit interrupter, AF CI, provides enhanced protection from fires resulting from arc faults. Our fault circuit interrupt her's use electronics to recognize an arc fault, and interrupts the circuit when the fault occurrence.

Arc fault circuit interrupt her's continuously monitor the current and voltage characteristics in a circuit, senses variations in these characteristics, it automatically opens the circuit, trips the breaker, when arc fault characteristics are detected.

An arc fault is an unintentional electrical discharge, and electrical arc, characterized by low and erratic current.

Arcing generates high intensity heat, and expels burning particles, which can easily ignite combustible materials.

A receptacle type ground fault circuit interrupt her is used in place of a standard duplex convenience outlet.

Circuit breaker ground fault circuit interrupt her's are installed in panelboards in buildings equipped with circuit breakers. This gives protection to the entire branch circuit. By providing overcurrent protection as a circuit breaker and serving to provide ground fault circuit protection, it serves two purposes.

There are three types of arc fault circuit interrupt her's: circuit breaker types, convenience outlet types, and portable types.

Circuit breaker types provide branch circuit wiring protection in the form of a circuit breaker.

The grounding, grounded conductor insulation, must be color-coded green, green with one or more yellow stripes, or may be a bear conductor on small conductors in cables.

Code no longer requires specific colors for color coding of ungrounded hot conductors, except for the Y phase on Delta connected, three phase systems.

Single receptacle is indicated by a circle with a single line running horizontally through it

Duplex receptacle is indicated by a circle with two horizontal lines running through it

Triplex receptacle is indicated by a circle with three horizontal lines running through it

Duplex split wired receptacle is indicated by a circle with two horizontal lines running through it, one of the semi circles drawn is shaded dark.

1 horsepower is equivalent to 746 Watts.

Electric motors have an advantage over fuel powered motors, that they can deliver more horsepower than their rating.

Equipment grounding refers to a grounding conductor or grounding path that connects the non-current carrying metal components of equipment.

Equipment grounding extends from the outlets, to the neutral busbar at the service entrance equipment.

Properly bonded, a metal raceway, meeting conduit, or armored cable system, can serve as a means of equipment grounding, so an equipment grounding conductor is not actually needed.

Equipment grounding in system grounding electrode's must be bonded. Bonding is accomplished by installing an additional grounded conductor, or by permanently joining metal components in a circuit.

Voltage across any two ungrounded conductors, XY and Z, is 208 V single phase power, since each phase is one third out of phase.

Equipment that is designed to operate on three phase power, such as a three-phase motor, is connected to the three ungrounded conductors, XY and Z phases.

Large retail shopping malls, schools, grocery supermarkets, and office buildings may use this system for its 277 V fluorescent lighting capabilities

Especially where fixtures are not located closer than 3 feet away from windows, platforms, and fire escapes.

On a two wire branch circuit, such as 120 V with one ungrounded conductor and one grounded conductor, the grounded conductor carries current equal to the load.

For example, if the ungrounded hot conductor, is feeding a load of 12 Amps, then the grounded conductor carries 12 Amps to the ground. Therefore, the grounded conductor must be sized to the same amperage as the ungrounded hot conductor.

Series arcing faults occur across the break of a single conductor

For example, in electrical wire may be cut by a nail or screw used to mount a wall hanging, resulting in this type of arc fault.

Ground arcing faults are arcs between a single conductor and ground, such as those that might occur when wires or chords touch vibrating metal.

Ground arcing faults may also occur in appliances, wall plugs, or switches, where the internal wires were not installed properly, and where connections came loose.

If needed, the grounding conductor kids safely carry current to ground in the event of a lightning strike, or in cases of damage or defect in the circuiting, appliances, devices, or equipment.

Grounding a van electrical branch circuit enables current to take an alternate path back to the overcurrent protection device, if and electrical device or appliance short circuits.

In an electrical system, grounding is required to protect building occupants and electrical equipment.

Grounding an electrical system begins with a ground, which is an electrode in direct contact with the earth itself.

Extremely low frequency electromagnetic fields, EMF, are silent and invisible magnetic field produced when electricity runs through wires. High levels of extremely low frequency electromagnetic fields can cause computer monitor interference, and Raise potential health concerns.

High levels of electromagnetic fields produce electromagnetic interference, EM I, which reveals itself as visible screen jitters in the video displays, humming in telephone and audio equipment, and data errors in magnetic media or digital signals.

When a hot, bear conductor inside and appliance, inadvertently touches the metal housing, the housing may become charged with electricity.

If a person touches the faulty appliance, and at the same time touches a grounded metal object, such as a water Fossett or a metal sink, The person will receive a shock, because the person's body serves as an inadvertent path to ground.

240, 120 V, alternating current, three phase, four wire system, is another fairly common electrical service found in commercial and industrial buildings, where three-phase motors, motors above about half horsepower, and equipment such as a large air conditioners are used.

In this three phase, four wire, delta connected system, the midpoint of one phase winding is neutral, to provide 120 V between phase a, and ground, and phase C and a ground.

A grounded conductor is required to complete a single phase circuit, by connecting the ungrounded, meaning hot, conductor, to the ground. The neutral conductor is a grounded conductor that serves more than one circuit.

It carries the unbalanced load between two crowded, hot conductors. Both conductors complete the circuits by connecting it to ground, and therefore are treated as current carrying conductors.

The 120, 240 V, alternating current, single phase, three wire system, is the most common residential electrical service in use today.

It is also used on a limited basis in light commercial buildings, small office buildings, churches, and retail shops and stores.

typically, system design been begins with selection of a building system voltage, which is dependent on sizes and types of connected loads, utilities near the building, local codes and ordinances, economics, and safety.

It is more economical to distribute power at high voltage.

208, 120 V, alternating current, three phase, four wire system is an older electrical service found in small commercial buildings, and high-rise building's, where three-phase motors, motors above about half horsepower, and equipment such as large air conditioners are used.

It is not used very often in industry, because a 480 V system is more economical for large motor loads.

A grounding system should also be connected to an electrode made of at least 20 feet of electrically conductive steel reinforcing bars, encased in at least 2 inches of concrete, that is part of a foundation or footing in direct contact with the earth.

It should also be in contact with an electrode made of a steel or iron plate, that is at least one quarter inch thick, with at least 2 ft.² of the plate surface in contact with exterior soil.

The primary difference between an appliance with a three prong plug and in appliance with a two prong plug is the appliance casing. If an appliance casing is a good conductor, made of metal, then it must have a grounding conductor and a three prong plug.

Many new or household electrical appliances and tools are double insulated. Examples include coffee makers, blow dryers, electric drills, and similar small power tools and appliances.

Arc faults are caused by the breakdown of the protective insulation that surrounds household wiring. These breakdowns occur naturally, as the wiring ages, and can be exacerbated by dust, settling, and shifting of a homes foundation, or by rodents.

New wiring is also at risk from drywall Staples, picture hanging nails, or any sharp objects that could Nick the wire. Current residential breakers only detect and react to power overloads, not arc faults.

Grounded conductors.

On a single phase, branch circuit, which is beyond the service equipment, and any feeders and originating at the panelboard, a grounded conductor serves as the crowded leg of the circuit.

It can also be connected to an electrode made of a grounding ring of bare copper wire, no smaller than number two American wire gauge, that in circles the building at a depth of no less than 2.5 feet below grade.

Or it can be connected to the structural metal frame of the building, where the frame is effectively grounded.

Parallel arcing faults result from direct contact of two wires of opposite polarity. Such faults are caused by appliances or extension cords that are afraid or ruptured, Staples or other fasteners that Pierce or pinch insulation or construction wire.

Parallel arcing faults are also caused by pierced appliance or extension cords, wire or cord installation that has cracked from age, heat, corrosion, or bending stress.

Convenience outlet types: and outlet arc fault circuit interrupt her for protecting connected cord sets and power supply cords in the form of an outlet receptacle.

Portable type: a portable arc fault Circuit interrupt her for protecting connected cord sets and power supply cords, that can be moved from outlet to outlet.

Where permanent ground fault circuit interrupt her's are not possible or practical, portable ground fault circuit interrupt her's may be used.

Portable types can be plugged into a convenience outlet so in electrical appliance plugged into the ground fault circuit interrupt her is protected.another type is in extension cord, such as those required on hairdryers.

A power surge is a sudden increase in electrical current or voltage that is very short in duration. This increase may be caused by lightning, or a sudden power spike caused by a problem in the utility transmission and generating system.fluorescent light flickering can also cause a power surge.

Power surges can damage sensitive electronic equipment such as computers, and reduce the life of the equipment.

Three types of ground fault circuit interrupt her's are commonly available for use in a building.

Receptacle outlet types, circuit breaker types, and portable types.

Double installation of an appliance or power tool protects the user from electric shock, by creating a non-conducting barrier between the user and the electric components inside the appliance.

Small appliances and power tools with double insulation are not required to have a grounding conductor, therefore they are allowed to have only two prongs.

A surge protection device, SPD, is an electrical device that prevents power surges from reaching electric and electronic equipment or other devices. Surge protectors work by instantaneously limiting the transient voltage from a power surge to a level that is safe for the equipment by diverting the large surge current safely to ground.

Surge protection devices divert the surge by allowing the current to flow past, rather than through the protected equipment.

At the panelboard, a grounding conductor is added, and runs continuously through all branch circuits.

The availability of 120 V or 208 V in single or three phase, leads to a number of circuit or feeder arrangements, that can supply 120 V single phase, 208 single phase, 208 three phase, and 120, 240 V three phase power.

At the switchboard or panelboard, the grounding conductor is added.

The availability of 120 V, or 240 V, leads to a number of circuit or feeder arrangements, that can't supply 120 V, 240 V, and 120, 240 V.

A capacitor motor operates on single phase alternating current only. The capacitor stores and discharges energy to help start the motor rotor.

The capacitor motor is more efficient and it has a better starting torque then the split phase motor.

Two wire, single phase color coding

The grounded cable is white, and the ungrounded cable is black.

Four wire, single phase circuiting color coding

The grounded cable is white, and the ungrounded conductors are black, red, and blue.

Three wire single phase circuiting color coding

The grounded conductor is white, and the ungrounded conductors are black and red.

Five wire circuitry color coding

The grounded conductor is white, and the ungrounded conductors are black, red, blue, and yellow.

The grounding conductor is a continuous conductor, that connects the ground to the neutral busbar, and the grounding conductor busbar in the service equipment, main panel board.

The grounding conductor does not normally carry current. Instead, it links ground to the metal frames or housings of appliances and motors, and the metal boxes containing outlets and switches.

Higher voltage means smaller conductor sizes.

The savings for larger conductors, feeders, of moderate length can be significant. Higher voltage however is more dangerous than lower voltage is.

120 V, alternating current, single phase, two wire system, is the most basic system voltage used. It was used in the first electrical services two buildings, however, nearly all have since been upgraded.

The service entrance provided to the service equipment is by two conductors, one ungrounded hot conductor carrying 120 V, and one neutral conductor. Voltage measured between the ungrounded hot and neutral conductors is 120 V

In the system, small transformers in electrical rooms step down the voltage from 480 V, to 120 V, for small equipment and convenience outlets.

The ungrounded hot conductors, are known as the XY and Z phases. Voltage across the connection of any single ungrounded conductor and the neutral conductor provides 277 V single phase power.

The service entrance conductors feeding the service equipment are three conductors: two ungrounded, live conductors, each carrying 120 V, and one neutral conductor.

The ungrounded, hot conductors, are known as the a and B legs.

A third conductor, known as the grounding conductor, provides supplementary but important grounding protection. The grounding conductor is not normally a current carrying conductors, but is energize only on a temporary, emergency basis, when there is a fault between an ungrounded conductor and any metal associated with the electrical equipment.

There is often confusion between the definitions of the grounded conductor, and the grounding conductor because the grounding conductor is commonly referred to as a ground.it is more correctly called a grounding conductor.

A neutral conductor is a grounded conductor that is shared between two or more ungrounded conductors.

Therefore, a neutral conductor is frequently called a shared neutral, or a common neutral.

The grounded conductor completes the circuit, by connecting the ungrounded, hot conductor, to the ground.

Therefore, in circuit design, the grounding conductor is considered to be a current carrying conductors, because it serves as a return path back to the circuits power source.

The basic application of an arc fault circuit interrupt her is protection of 15 A and 20 amp branch circuits in single and multi family residential occupancies.

They are available as circuit breakers with built in arc fault circuit interrupt her features that combined traditional thermomagnetic overcurrent protection, with the ability to detect and interrupt electrical arcs.

Grounded and neutral conductors should always be insulated, because they can carry current.

They should be continuous, because they provide a path to complete the circuit or circuits. The neutral conductor is grounded at the transformer, and at the service equipment.

Before about 1950, only two conductors were used to feed electrical energy beyond the panelboard to the 120 V branch circuit's in the building

This configuration relates to the two slotted convenience outlets found in older buildings.

Most relatively new commercial buildings in the United States are served with 480, 277 Volt electrical service

This is opposed to the 240, 120 V, and 208, 120 V, electrical services commonly used in the past.

Well the higher voltage provides increased capacity, it can result in an undesirable side effects tied to a combination of the higher voltage and the characteristic spacing between energized parts and grounded metal in electrical distribution equipment.

This small spacing between electrical components and high-voltage power creates a condition in which arcing faults can develop and persist fairly easily, resulting in melting of metal components, burning of insulation, and explosive arcing.

600, 346 V, alternating current, three phase, four wire system, is a less common electrical service in large commercial and industrial buildings, that is used to power specially designed heavy machinery.

This system is designed like the 480, 277 V system, except that 600 V and 346 V are available in the circuit or feeder configurations.

If a damaged, ungrounded hot conductor, and an appliance such as a refrigerator or drill has contacted the appliances metal housing, making the housing hot: without a grounding conductor connecting the appliance housing to the ground, the appliance housing would remain hot.

This would expose the user to a hazardous condition, and the possibility of electrical shock if he touches the live housing.

Voltage across any two ungrounded conductors is 480 V, single phase power.

Three phase motors and other equipment that operate on three phase power, are connected to the three ungrounded conductors.

Split phase motors operate on single phase alternating current only. The motor windings are configured so that single phase alternating current power is split into two phases that are half out of phase.

To split phase motor starts slowly with low torque, so it is not capable of starting heavy loads. Available in sizes up to 1/3 hp.

Later, the grounding conductor became a standard part of branch circuits. It relates to the extra slot found in three slotted convenience outlets, found in newer homes.

Today, three conductors are used to deliver electrical energy to the branch circuits in the building: one ungrounded hot conductor carrying 120 V, one neutral conductor, and one grounding conductor.

Arc fault circuit interrupt her's detect low level arc faults that traditional overcurrent protective devices, fuses and circuit breakers, cannot detect.

Traditional overcurrent protection perceives a low level arc fault as a normal load, unless the current flow exceeds its rating.

One and two pole ground fault circuit interrupt her circuit breakers are available. One pole ground fault circuit interrupt her breakers can be installed on the 120 V portion of a 120, 240 V system.

Two pole ground fault circuit interrupt her breakers are used in commercial and industrial applications.

A 120, 240 V branch circuit provides both 120 and 240 V two appliances, such as ranges and clothes dryers, controls, and light fixtures.

Typically, small motors run on 120 V, and heating elements operate on 240 V. A grounding conductor runs continuously through all branch circuits, and serves as a safety circuit in case of a short circuit.

Amperage determines conductor size, and higher voltage means lower amperage, which allows use of smaller conductors.

Use of high-voltage is introduces more complex safety issues, so use of high-voltage is in buildings is reserved for equipment with heavy loads.

In a simple, single phase circuit, the ungrounded conductor provides power to the load, and the grounded conductor provides a pass from the load back to the power source, which completes the circuit.

Voltage in the circuit is equal to the voltage on the ungrounded conductor. Went to ungrounded conductors in a single phase circuit are connected in a circuit, voltage in the circuit is double the voltage available on each ungrounded conductor.

Medium and high voltage systems carry voltages above 600 V, and may be used in special cases, such as the 2400, 4160 V three-phase system found in industrial and commercial installations, such as manufacturing plants and skyscrapers.

Voltage is higher than 600 V require heavy insulation and conductor shielding. Therefore, low-voltage systems less than 600 V are typically used in buildings.

The ungrounded hot conductors are known as the X, Y, and Z legs or phases.

Voltage measured across the connection of any single ungrounded conductor, XY or Z, and the neutral conductor, provides 120 V single phase power.

A ground fault circuit interrupt her continuously monitor is the current drawn through the ungrounded, hot, and neutral conductors of an electrical circuit.

When a leakage to ground that exceeds 6 mili amps is detected, the ground fault The ground fault circuit interrupt her instantaneously switches off power to the branch circuit or appliance, thereby protecting a person from the dangerous effects of electrical shock.this occurs in less than a heartbeat, about one 40th of a second, hopefully before serious or fatal shock occurs.

The ungrounded conductor is the initial current carrying conductors are in an alternating current system. The ungrounded conductor is frequently known as the hot or live conductor, because it feeds current to the circuit.

When an ungrounded conductor is grounded, meeting connected to ground, a closed circuit in single phase results.

Most alternating current 60 Hz electric motors are designed to operate at the theoretical 1800 or 3600 revolutions per minute.

When and appliance or piece of equipment must operate at a slower speed, this is accomplished by using a gear or pulley belt system, to gear down or gear up the required RPM.

This is the type of circuit used to power small appliances, small equipment, and lighting.

When to associated ungrounded conductors are connected in a single circuit, a higher voltage is delivered.

It requires an additional supplemental wire, called the grounding conductor, which is connected to the appliance cabinet or housing, and provides in additional grounding path in addition to the grounded conductor.

Without this additional grounding path, current could flow through a user who was touching a faulty appliance.