House wiring chap 2

National Electric Manufacturing Association (NEMA)

An Organization that develops electrical equipment standards that all manufacturers follow when designing and producing electrical equipment

Circuit Breaker

Automatic overcurrent device that trips into an open position and stops the current flow in an electrical circuit Single-pole breaker (on the left) and a two-pole breaker (on the right)

junction box

Box used to join several electrical wires into a circuit

UL Directories

For residential wiring, there is one UL directory that an electrician should consult on a regular basis and that is the General Information for Electrical Equipment Directory (White Book).

Ground Fault Circuit Interrupter (GFCI) Receptacles

GFCIs are used to protect people from electrical shock. The "reset" and "test" buttons on the front of the GFCI receptacle are used for regular testing and then resetting it.

OvercurrentProtectionDevices

In residential wiring, overcurrent protection devices consist of fuses or circuit breakers. - The NEC® states that overcurrent protection for conductors and equipment is provided to open the circuit if the current reaches a value that will cause an excessive or dangerous temperature in conductors or conductor insulation.

Fuse

Overcurrent protection device that opens a circuit when the fusible link is melted away by the extreme heat caused by an overcurrent May encounter two styles of fuses:Plug fuses Cartridge fuses

Conductor sizing

- Conductors are sized according to the American Wire Gauge (AWG). - Conductors used in residential wiring typically range in size from 14 AWG to 2/0 copper. - The larger the number, the smaller the conductor. - The smaller the number, the larger the conductor. - Conductor sizes larger than 4/0 are listed in kcmil. kcmil stands for 1000 circular mils. Examples: 250 kcmil, 500 kcmil, and 2000 kcmil

Cable Fittings and Supports

- Connectors are used to connect a cable to an electrical box. - Cables are supported by a variety of items, including staples, stackers, and cable straps.

Type NM-B

- Most common type; use in dry locations only - Has flame-retardant, moisture-resistant, nonmetallic outer jacket

Underwriters Laboratories, Inc. (UL)

- Most manufacturers of electrical products submit their products to UL. - OnceULdeterminesthatthe product complies with the specific standards for which it is tested, the manufacturer is allowed to put the UL label on the product.

Loadcenter

A type of panelboard that contains the main disconnecting means for the residential service entrance as well as the fuses or circuit breakers used to protect circuits and equipment like water heaters, ranges, dryers, and lighting

- Arc Fault Circuit Interrupter (AFCI) Receptacles

AFCI receptacles are intended to protect homes from the effects of arc faults. AFCIs are designed to detect a wide range of arc- faults to help reduce the likelihood of the electrical system being an ignition source of a fire.

approved

Acceptable to the authority having jurisdiction.

Nonmetallic-Sheathed Cable (Type NM)

Also known as "Romex ®" Least expensive wiring method to purchase and install Most common wiring method used in house wiring Typically is a two-wire or three-wire cable type A four-wire cable is available from some manufacturers. There is also a Type NM cable style made by some manufacturers that combines two two- wire cables into one cable so that two two- wire circuits can be installed at one time.

Conductor Ampacity

Ampacity is the current in amperes that a conductor can carry continuously under the conditions of use without exceeding its temperature rating. - A residential electrician must be able to choose the correct conductor size based on the ampacity needed for each circuit they are installing. - The ampacity of a conductor depends not only on the size of the conductor but also on what insulation type the conductor has.

Armored Cable (Type AC) and Metal-Clad (Type MC) Cable

Certain locations in the United States may not allow Nonmetallic Sheathed Cable (Type NM) in residential construction so Type AC or Type MC could be used. Both have a metal outer sheathing and provide very high levels of physical protection for the conductors in the cable. Electricians sometimes find it hard to tell Type AC (alsoknown as "BX" cable) and Type MC apart.

Receptacles

Contact device installed at the outlet for the connection of an attachment plug.

types of raceways

Electrical metallic tubing (EMT) Rigid polyvinyl chloride conduit (PVC) Flexible metal conduit (FMC) Electrical nonmetallic tubing (ENT) Liquidtight flexible metal conduit (LFMC) Liquidtight flexible nonmetallic conduit (LFNC)

ConductorConnections

In residential wiring, the most common type of wire connector used to splice two or more conductors together is called a wirenut. • They are used to connect conductors together in combinations of 18 AWG through 6 AWG and are a twist-on, solderless, and tapeless connector type. - Bare equipment-grounding conductors are often connected with something called a crimp sleeve. • This is a short tube, often made of copper, which can be placed over the ends of the conductors and crimped on using a proper crimping tool. - Smaller electrical devices like switches and receptacles typically have conductors connected to them with terminal screws.

Fasteners

Nail sare themost common fastener used in residential wiring. - They are used for things such as mounting electrical boxes and fastening running boards to building framing members. Fasteners (continued) - Anchorsareusedto mount electrical equipment on surfaces like sheetrock or masonry. - Examples Toggle-bolts W allboard screws Molly bolts Lead anchors Tap-Cons

Type NMC-B

Not used often in residential work; use in dry or damp locations - Has flame retardant, fungus and corrosion resistant, nonmetallic outer jacket

There are three types of service entrance cable:

SEU Cable is used for service entrance installations. SER Cable is similar to SEU. - Has four conductors wrapped in a round configuration. - Used as a feeder from service entrance equipment to a subpanel. USE Cable is used for underground service entrance installations.

Service Entrance Cable

Supplies electrical power from the utility company to a building's electrical system Can also be used to supply power to a large appliance, like an electric range

Junction Boxes

They are used when several conductors are spliced together at a point on the wiring system. The NEC® requires junction boxes to be accessible after installation without the finish of a building having to be altered. They must always be covered.

Handy or Utility Box

This type of box is primarily used for surface mounting and can accommodate one device such as a receptacle or switch.

Three types of Type NM cable

Type NM-B, NMC-B, MNS-B

devices

a unit of an electrical system intended to carry, but not use, electric energy.

Device box

an electrical device that is designed to hold devices such as switches and receptacles

Solderless connectors, often called crimp connectors

are crimped on to 21 the conductor with a tool specifically designed for crimping.

Special Receptacle Types

arger with a different configuration than the single or duplex receptacle. Two appliances typically require a special receptacle installation: - (A) Electric range - (B) Electric clothes dryer

switch boxes

boxes that usually contain just switches

Raceways

enclosed channels of metal or nonmetallic material designed expressly for holding wires or cables. in wiring may include Rigid metal conduit (RMC) Intermediate metal conduit (IMC)

cable type MN

has a clear plastic wrap around all of the conductors (bottom).

Cable type AC

has paper covering each conductor (top).

Conductors

in residential wiring are usually installed in a cable assembly. - They are made of • Copper • Aluminum• Copper-clad aluminum - Copper is preferred because of its great ability to conduct electricity, its strength, and its low instance of problems over the long term.

spliced conductors

referred to as a junction box

Tamper-resistant receptacle

slots are closed until a plug is inserted

Cable ties,

sometimes called tie wraps, are often used to fasten a bundle of wire or cable together.

Outlet box

used to indicate a box that may contain switches, receptacles, or a lighting fixture

Screws

used to secure electrical equipment to a variety of materials. - Examples Wood screw Sheet metal screw Sheetrock screw Self-tapping screw

Lugs

used to terminate larger conductors and are used for one solid or one stranded conductor unless the lug is specifically designed for more than one conductor.

Nuts and washers

used with threaded fasteners in many applications to help secure an electrical item in place. - Section 110.14(D) in the NEC® states that where a tightening torque is indicated on equipment or in the installation instructions, a calibrated torque tool must be used, unless the instructions provide an alternative method to achieve the proper torque requirement.

Types of devices

• Switches • Receptacles • Attachment plugs • Lampholders

Conductor Color Coding

- The NEC® requires that each conductor be color coded to indicate the function that it performs in a circuit. • Black - Used as an ungrounded or "hot" conductor and carries the current to the load in 120-volt circuits • Red - Also used as an ungrounded or "hot" conductor and carries current to the load in 120/240-volt circuits like an electric clothes dryer circuit White - Used as the grounded circuit conductor - Returns current from the load back to the source - Often called the "neutral" conductor, but only truly "neutral"when used with black and red wire in a multiwire circuit • Bare - Used as equipment-grounding conductor that bonds all non-current carrying metal parts of a circuit together; does not carry current except in a ground fault situation • Green - Used as an insulated-equipment-grounding conductor - Could be green with one or more yellow stripes

Nationally Recognized TestingLaboratories (NRTL)

- The National Electrical Code® (NEC®) states that the Authority Having Jurisdiction (AHJ) approves electrical materials used in an electrical system. - Many AHJs base their approval of electrical equipment on whether it is listed and labeled by an NRTL. - The NRTL tests and then evaluates a product, and if the product is found to comply with the requirements of one or more appropriate product safety test standards, it is certifiedand placed on the NRTL's list. - Section 110.3(C) states that only qualified electrical testing labs can test, evaluate, and then list electrical products.

type MNS-B

- Used in new homes with home automation systems - Contains power conductors, telephone wires, coaxial cable for video, and other data conductors all in the same cable - Has moisture-resistant, flame-retardant, nonmetallic outer jacket

Metal Device Boxes

A metal device box has many features, including the capability of having the sides of the box removed and the boxes ganged together to make a box that can accommodate more than one device. Boxes used to install receptacles or switches at specific locations on an electrical circuit Standard box opening 3" x 2" with a depth that ranges from 1-1⁄2" to 3-1⁄2" Most common metal device box size 3" x 2" x 3-1⁄2"

Safety Switches

A safety switch is used as a disconnecting means for larger electrical equipment. - It is typically mounted on the surface and is operated with an external handle.

Panelboard

A single panel that includes automatic overcurrent devices used for the protection of light, heat, and power circuits

Duplex Receptacle

The most common type of receptacle used in residential wiring is a duplex receptacle rated for 15 amperes at 125 volts. It consists of two single receptacles on the same mounting strap

Three Primary NRTL

Underwriters Laboratories, Inc. (UL) • Most recognizable of the NRTL. - CSA International (CSA) • Once known as the Canadian Standards Association; this lab tests, evaluates, and lists electrical equipment. - Intertek Testing Services (ITS) • Formerly known as Electrical Testing Laboratories (ETL).

Special Boxes for Heavy Loads

Used for heavier loads such as ceiling suspended paddle fans Can be made of metal or nonmetal Specifically designed and tested to support heavier loads

Underground Feeder Cable (Type UF)

Used for underground installation of branch circuits and feeder circuits Also can be used in interior installations, but must be installed following the installation requirements for Nonmetallic-Sheathed Cable (Type NM)

Switches

Used to control the various lighting outlets installed in residential wiring. The single-pole switch used in 120-volt circuits to control a lighting outlet or outlets from only one location is the most common. The double-pole switch is used on 240-volt circuits to control a load from one location. Example: - Electric water heater Three-way switches are used in 120-volt circuits to control a lighting load from two locations. Four-way switches are used in 120-volt circuits to control a lighting load from three or more locations. They are used with two three-way switches. Combination devices have a combination of two devices, both of which are mounted on the same strap. There could be two single-pole switches, a single-pole switch and a three-way switch, or a single-pole switch with a pilot light.

Outlet boxes

Used when installing lighting fixtures in a ceiling or on a wall Used when connecting small or large appliances Larger than a device box Provides more room for different wiring situations Found in round(top), octagon(A), or square(B) shapes -Raised plaster rings are necessary when a square box is used and you want to install a switch or receptacle. -Raised covers are used when you want to install a device in a surface-mounted situation

Nonmetallic Device Boxes

Usually made of PVC, phenolic, or polycarbonate Lightweight, strong, very easy to install, and inexpensive Used with a nonmetallic- sheathed cable wiring method Available in (A) single-gang, (B) two-gang, and (C) three- gang styles