PDX_22_Electrical Part 2 Flashcards
Tubes that house, protect, support, and provide grounding for wiring
Conduit
Means by which a current is conducted
Conductor
Safeguards that allows a current to find an easy path of the earth, eliminating electrical load and protecting people from shock.
Grounding
Accidental low resistance connection between two components of an electrical circuit that are meant to be a different voltages.
Short circuit
A material of very low conductivity used to separate electrical conductors and prevent leakage of electrical currents
Insulation
A device which converts power and one kind of system to power in another form, such as loudspeaker which converts electric power to acoustic power
Transducer
Conductor sizes are based onthese two designation systems
American wire gauge (AWG)
And
thousand circular mill (MCM)
In the American wire gauge system increasing gauge numbers indicate:
Decreasing wire diameters.
Number 0000 AWG,
Aka 4/0, is largest. Above that MCM Cable sizes of 250, 400, and 500 are used.
Circular mill uses this minimum gauge in buildings
Minimum 14 gauge
This why are typically requires a special installer. Oxide can form when joints loosen and or overheat. Must be larger than copper to carry amperage. Limited to primary circuits because of overheating. Primarily commercial application.
Aluminum
This wire type has the same caring capacity as aluminum but smaller and cheaper. Most cost-effective for small and medium size wire and cable. Primary use is residential and small construction.
Copper wire
This cable type requires no conduit. Must be protected from damage within walls. Two or more plastic insulated conductors and ground surrounded by a moisture resistant sleeve. Typically used in residential wood framed buildings less than three stories.
Romex
This cable type is flexible metal clad. It has two or more plastic insulated conductors in case in the spiral wound strip of steel tape. No conduit is required and it can easily be pulled. Hence its use in remodels and residential.
Flex metalclad cable (BX)
This conductor is a rectangular bar of copper that carries high-voltage. It’s used in place of very large cables and high currents.
Busbar
Multiple busbars in a metal housing.
Bus away
Primary conduit functions:
Support and protect wiring.
Serves as ground.
Protects surrounding construction from fire in case of overheating.
This type of conduit is the safest type. After pipe was installed (indoor/outdoor) wires are pulled through. Connections are rigid and threaded like plumbing pipes. Connect to j-boxes and devices.
Rigid steel
This type of steel conduit with Center walls but same outside diameter as rigid. It’s more economical and also used with threaded fittings.
Intermediate metallic conduit
This conduit pipe is used everywhere except underground. It reduces vibration transmission from equipment we’re not possible to install rigid.
Flexible metal conduit
This conduit type is the thinnest metal. It’s too thin to thread so connections are made with clamps. It’s easy and fast to install but not allowed in hazardous areas.
Electric metallic tubing
These are channels for holding electrical wires
Raceways
These proprietary steel raceways her cast into concrete floor at regular spacing of 4, 5 or 6 feet.
Underfloor ducts
These raceways are part of the structural floor, essentially metal decking used for cable raceways
Cellular metal floors.
This thin flat wiring can be laid under carpet without protruding, must be used with carpet tile for ease of access
Under carpet wiring
The ratio of average power used to the maximum power demand
Load factor
The buildings electrical system is designed to avoid peak electricity use
Load control
Switch that is usually magnetically operated used to open and close an electric current
Contactor
Set of electrical conductors which extends from the source of energy to a distribution center
Feeder
The portion of the buildings electrical system extending from the utility companies wires to and including the main switch and meter
Service
Central electrical distribution center that consists of an assembly of switches, circuit breakers and cables or bus ducts that distribute power to the building
Switchgear
It component of an electrical supply system which divides and electrical power feed into subsidiary circuit 12 providing a protective fuse or circuit breaker for each circuit, in a common enclosure
Panelboard (breaker box)
The insulated wires that run between the outlet and the panel board
Branch circuit
Devices used to protect from overload and short-circuiting
Circuit protection
Switching device that can make, carry, and break current under normal circuit conditions
Circuit breaker
A thin strip of metal that melts and breaks and electrical circuit if the current exceeds the safe level
Fuse
Detect small currently and disconnect the hot wire, typically used in kitchens, bathrooms, and outdoor outlets
Ground fault interrupter (GFI)
Type of system which mean clued lighting, generators to provide back up our resources in a crisis or when regular systems fail
Emergency power system
And electrical apparatus that provides emergency power to a load when the input source fails. Typically used to protect computers, data centers, telecom equipment, or whatever power outage can disrupt business.
Uninterruptible power supply (UPS)
Circuit breakers for main disconnects are ____ amps
100 A for main disconnect
To account for future expansion, systems should be oversized __%
25%
Every circuit has these three wires:
Hot, neutral, and ground wire
To avoid the risk of electric shock, it’s recommended that appliance housings be grounded to :
A cold water pipe
This is typically used on any 15 or 20 amp circuit where water is or might be present. Always within 6 feet of water source.
Ground fault interrupter
NEC requires that for single motor installation, the current used in the wire size calculation must be__times the load current from the applicable single phase or three phase tables.
1.25 x the load current
Low-voltage switching operates on a__V circuit
24 V circuit
And electrically controlled switch used for switching a power circuit, similar to relay but with higher current ratings. Can be remote controlled.
Contactors
Raceway as of now become a major architectural consideration that must be addressed early in the design process because of
Computers and networking equipment
An outlet where one is always energized, and the other is controlled by switch
Split wire receptacle
Typical outlet mounting height above finished floor:
12-18 inches above finish floor
15 inches for ADA
Maximum distance between outlets:
No point should be further from an outlet then:
12’0” maximum between outlets.
no point should be further than 6 feet from an outlet
To count as a required power receptacle, floor receptacles must be no further from an exterior wall than
18 inches
Minimum circuits required for kitchen counter:
Maximum number of outlets per 20 amp circuit in the kitchen:
Minimum of two circuits in the kitchen,
No more than four outlets per 20 amp circuit in the kitchen
Maximum distance any point on the wall above a counter can be from an outlet:
No greater distance than 24 inches
If the building is emergency power supply consist of batteries, they must have a full load capacity of __mins.
90 minutes
For the purpose of protecting overall building electrical load, continuous loads should be calculated at__% of their actual value
125% of their actual continuous load value
