Lesson 10- Pt 2

GFCI circuit breaker

GFCI circuit breakers have the advantage of protecting every fixture on the circuit—lights, outlets, fans, etc. They also provide protection against overloads and simple short-circuits. - Pros are using GFCI circuit breakers more frequently since they allow builders and electricians to use standard (inexpensive) outlets and simply install a single GFCI circuit breaker in the panel box.

Purlin

Horizontal member between trusses that support the roof.

____ cable is a fabricated assembly of insulated conductors, No 14 through No 1, wrapped with impregnated paper and enclosed in an interlocking spiral-wound flexible metal sheath with an internal bonding strip of copper or aluminum in contact with the sheath's entire length.

MC Cable (Metal-clad cable).

Type MC cable differs from AC cable because _____.

MC has a separate full grounding conductor - the armor is not part of the grounding

Branch Circuit

The circuit conductors between the final overcurrent device protecting the circuit and the outlet(s).

NM cable in sizes 6/2 or 8/3 or larger may be installed in unfinished basements _____.

directly to the underside of joists

Armored cable, without insulated equipment grounding conductor, may be ____.

fished in air voids of masonry walls not exposed to excessive moisture

Armored cable ____.

must be secured by approved fittings within 12 inches of every box, cabinet, enclosure, or conduit body. -must be secured by approved staples, straps, hangers, or similar fittings - The radius of the curve of the inner edge of Type AC cable bends must not be less than FIVE times the diameter of the cable.

Metal-clad cable is not permitted ____.

outdoors, if the metallic covering is the interlocked armor type without an overall jacket

GFCI receptacle

A fast-acting receptacle that detects low levels of leakage current to ground and opens the circuit in response to the leakage - Completely compatible with any standard outlet, it can protect other outlets "downstream" (any outlet receiving power from the GFCI outlet).

Type FCC cable

"Flat Conductor Cable". Consists of three or more flat copper conductors placed edge to edge separated and enclosed within an insulating assembly. This type of cable is used for appliance or individual branch circuits installed inside floor surfaces. - Primarily used under carpeted floors in banks and office buildings for wiring receptacles in open floor areas. (324.1) - Only permitted to be installed under removable carpet squares on dry or damp floor surfaces that are sound, smooth, and continuous, such as concrete and wood, and on wall surfaces in surface metal raceways. (324.10) - Carpet squares are required to have a release-type adhesive and must not be larger than 1 meter (39.37 in) square. (324.41)

Type MC cable

"Metal clad cable". A factory assembly of one or more insulated circuit conductors enclosed in an armor of interlocking metal tape or a smooth or corrugated metal sheath. - Overall MC Cable has a lot of capabilities (services, feeders, branch circuits), can be used in many locations (assembly, hazardous, plenums), and can save time and money (30-50% over conduit and wire). An MC Cable installation can be neat and orderly when installed per Article 110.12. - Support every 6 feet

NM Cable

"Non-Metallic Sheathed Cable: A factory assembly of two or more insulated conductors enclosed within an overall nonmetallic jacket. - used for interior AC wiring - The radius of the curve of the inner edge of Type NM cable bends must not be less than FIVE times the diameter of the cable. *Romex*

SE Cable

"Service entrance cable"- A single conductor or multiconductor cable provided with an overall covering, primarily used for services SE Cable has a flame-retardant, moisture-resistant covering.

Type UF

"Underground Feeder". The type of cable used for DIRECT BURIAL of underground feeder wires (soil but not concrete). - rated for ampacity using the 60°C column of 310.15(B)(1) NOT permitted to be used as service entrance cable or movie theaters

Romex

- Nonmetallic sheathed cable -consists of 2 OR MORE plastic insulated & ground wire surrounded by a MOISTURE-RESISTANT plastic jacket -can be used in WOOD STUD residential buildings & buildings not exceeding 3 floors as long as it is used with wood studs and protected from damage by being concealed behind walls & ceilings

Type NM cable is permitted to be used in ____ (if of the correct type construction).

- multifamily dwellings - one- and two-family dwellings - stores and offices

Ground faults

- occur when an ungrounded conductor comes in contact with a grounded surface or grounded equipment. - In and near the home, ground faults most commonly occur around water or moisture. Water and electricity do not mix, and there are many places in the home and outside where the two exist in close proximity. - All switches, sockets, breakers, and circuits for those rooms and areas of the home should be GFCI-protected for your family's safety. - Ground faults are technically considered "shorts", because the electrical flow has bypassed the circuit wiring, causing the circuit breaker to trip. - But for an electrician, a ground fault is generally defined as the situation when a hot wire makes contact with either the grounding wire or a grounded portion of the system, such as a metal electrical box. - A ground fault represents any electric path between a source of current and a grounded surface. A ground fault occurs when AC current "leaks" and escapes to the ground. How this occurs is significant. If your body provides a path to the ground for this leakage, you could be injured, burned, severely shocked, or electrocuted. Since water conducts electricity so well, ground faults occur more frequently in areas near water. Water provides a conduit for electricity to "escape" and find an alternate path to the ground. HOT ---> GROUND WIRE/GROUNDED PORTION OF SYSTEM.

The minimum depth for direct burial of Type UF cable for a residential branch circuit rated 120 volts and 20 amperes or less which has GFCI protection is ____ inches.

12 (UF or USE conductors).

Short circuit

A connection that allows current to take the path of least resistance

Electrical short

A situation in which an electrical signal takes a path other than the intended path. In the case of twisted pair wiring, a short means that a signal sent on one wire arrives on a different wire. A short circuit is any electrical flow that strays outside its intended circuit with little or no resistance to that flow. The usual cause is bare wires touching one another or wire connections that have come loose. The immediate impact is that a large amount of current suddenly begins to flow. This in turn causes the circuit breaker to trip, instantly stopping all current flow. This condition is known as a "short" circuit because the current is bypassing the full circuit wiring and flowing back immediately to the source by a shorter pathway. For electricians, a short circuit is usually defined as a situation in which a hot wire makes contact with a neutral wire, such as when a hot wire loosens from its connection and makes contact with the neutral wire or vice versa. HOT ---> NEUTRAL

GFCI (Ground Fault Circuit Interrupter)

A special electrical outlet that has a circuit breaker built in which trips due to even small changes in current; normally installed in bathrooms, kitchens, laundry rooms etc. - precisely monitors the balance of electrical current moving through a circuit. If the power goes where it shouldn't, like in a short, the GFCI immediately cuts off the electricity. - prevents fatal electrical shocks through the elimination of sustained current draw when a short occurs.

Beam

A structural member, usually horizontal, that carries a load that is applied transverse to its length.

Rafter

A wooden beam that supports a roof

Feeder

All circuit conductors between the service equipment (meter, main disconnect) to the source of a separately derived system, or other power supply source and the final branch-circuit overcurrent device.

____ fittings are not permitted to be used with Type MC cable.

Armored cable, Nonmetallic-sheathed cable, Flexible metal conduit

Type AC Cable

Armored cable; type of cable sheathed in metal. Also, any cable used for AC wiring Allowed to be installed: - in both exposed and concealed work - embedded in plaster finishes on brick or masonry in dry locations - to be run in the air voids of masonry block where not exposed to excessive moisture Support every 4.5 feet

Service-entrance conductor

The wires running from the exterior of the building to the service (meter, main disconnect). - Run from the weather-head (exterior point of attachment) from the utility pole to the electric panel (usually the circuit breaker box)

Recessed fixtures

Widely used in residential & commercial - Residential limited to incandescent downlights because they can be located in the limited space between floor or ceiling joists. Commercial use recessed troffers that fit within suspended acoustical ceiling systems. Used as general downlights or wallwashers.

Truss

a framework, typically consisting of rafters, posts, and struts, supporting a roof, bridge, or other structure.

Joist

a length of timber or steel supporting part of the structure of a building, typically arranged in parallel series to support a floor or ceiling.

Type MC cable is permitted for ____.

a.branch circuits b.feeders c.direct burial (if identified) d.all of the above

Ampere

unit of electric current