CHAPTER 2, ENCLOSURES AND RACEWAYS Flashcards
• are ELECTRICAL BOXES and CABINETS that are made of metal or non-metallic materials that protect conductors, connections, controls, and other equipment
• they protect wiring, devices, and equipment from damage from accidental contact, wear, corrosive, atmospheric exposure, and sunlight
• for faulty enclosed conductors, connections, controls, and electrical equipment, enclosures contain the arc and
flaming, thereby confining damage from fire
enclosureS
• are METAL AND NONMETALLIC ENCLOSURES that hold devices such as switches or outlets and safety PERMIT wiring connections
• boxes are in four primary shapes: square, rectangular, octagonal, or round
• boxes can be joined together to accommodate multiple outlets or switches, namely; two-gang, three gangs, or four gang boxes
electrical boxeS
• special type of electrical box used to ENCLOSE CONDUCTOR CONNECTIONS
• connections are commonly called junctions in the trade
junction boxeS
kind of junction box that allows access to a raceway for
SNAKING conductors through the raceway
pullbox
in most boxes and enclosures, it can be EASILY REMOVED
to allow wiring to enter the box
knockout
• required for various single or combinations of switches, convenience outlets, blank covers, and dimmers; plastic is a commonly used material
• attached with screws to the switch or receptacles
• all the boxes should be finished with a cover plate
cover plateS
• an ENCLOSED CHANNEL such as conduit, tube, or gutter used for holding WIRES, cables, or bus bars
• in some cases, metal __________ that are fully bonded serve to provide a path for the flow of fault current to
ground
RACEWAY
- a HEAVY GALVANIZED STEEL or aluminum tube that looks like the galvanized steel pipe used for plumbing applications, except it is much smoother and is labeled with a UL Listed stamp or label has THREADED connections much like a pipe
- can be used in contact with the earth and embedded in concrete
RIGID METAL CONDUIT
• galvanized steel or aluminum tube that has a thinner wall than rigid metal conduit
• has threaded connections much like pipe or threadless connectors and couplings
• can be used in contact with earth and embedded in concrete
INTERMEDIATE METAL CONDUIT
• THIN _ WALLED GALVANIZED STEEL or aluminum tube in nominal diameters up to 4 in.
• CANNOT BE THREADED
• labeled with UL Listed stamp or label
• joined with threadless compression couplings, couplings that are crimped into the tubing with a special indenting tool, or fittings that are TIGHTENED WITH SCREWS
ELECTRICAL METALLIC TUBING
• a FLAME - RETARDANT corrugated plastic tube that is semi flexible such that it can be bent by hand. • must be used behind fire-rated finish materials
• permitted in damped locations and can be set in concrete above ground
• can also be solvent welded to rigid _____________
(PVC) conduit
• can be used in any building, but special precautions are required when used more than three floors above grade
ELECTRICAL NONMETALLIC TUBING, polyvinyl chloride
• THIN WALLED PIPE OF PVC
- joined with fittings that are SOLVENT WELDED
RIGID NONMETALLIC CONDUIT
similar to armored cable yet, installed without cables or wiring in it; wiring must be pulled
FLEXIBLE METAL CONDUIT
similar to flexible metal conduit but covered with plastic, a WATERTIGHT JACKET that is sunlight resistant
• unlike flexible metal conduit, the special connectors are watertight
LIQUID TIGHT FLEXIBLE METAL CONDUIT
• a flexible plastic conduit used similarly to flexible metal conduit
cannot be used over 6 ft. in length
LIQUID TIGHT FLEXIBLE NONMETALLIC CONDUIT
are hollow voids in floors made of precast concrete slabs (core slabs) found in certain precast concrete buildings
cellular concrete floor racewayS
• involves cutting, bending, and threading lengths
EMC, EMT, ENT
• a run of conduit should be straight and direct
so true
_________ or __________ must support the conduit in the entire run
strapS , hangerS
• the number of conductors in a raceway is based on the
size of the conduit,
type of conductor insulation,
size of conductors
• several conductors fed into conduit should be kept
___________, _________, and _________ and _____________.
parallel, straight, and kinks and bends-free
• is of a standardized, factory assembled enclosure consisting of outer DUCT LIKE HOUSING, BUS BARS, and INSULATORS
•__________ systems are used in service equipment or as __________ because they are designed to carry a large amount of current
BUSWAY, feeders
A type of busway system that used to deliver a LARGE AMOUNT OF POWER with LOW VOLTAGE DROP • available in sizes from 600 A to several thousand amps
FEEDER BUSWAY
• Another type of busway system used to provide POWER TAP-OFFS at multiple points • available in 100 A- 3000 A sizes
PLUG-IN-BUSWAY
make power distribution flexible
PLUG-IN-BUSWAY
____________ is available anywhere along the busway without necessitating the major service interruption.
Power
Connections cannot be made at any point along the busway.
false, pwede ra uy
Rigid and flexible conduit or flexible _____________ extends from the busway to the equipment piece.
bus drop cable
• are only used in large commercial and industrial installations where LARGE LOADS ARE CONCENTRATED (600 A and above), where large numbers of taps are required, or where superior fire and mechanical injury protection is desirable.
busway
can also be salvaged and moved more easily and costeffectively than ordinary conductors.
BUSWAY
___________________ are sheet metal or nonmetallic, FLAME-RESISTANT plastic throughs that serve as HOUSING that encloses and protects conductors
• access to the enclosure interior is through a hinged door or removable cover
• _________________ carry large conductors
wirewayS
