Electrical (1.2) Flashcards
Energy flow through a _________ because of a difference in electrical change between two points in a circuit
conductor
Energy flow through a conductor because of a difference in electrical change between two points in a circuit
Where can service utilities be placed/sourced from?
Underground and overhead service depending on accessibility
Overhead placement of main power source to building pros/cons?
Pro: less expansive, easily accessible for maintenance, can carry high voltages over long runs
Cons: not ideal in urban settings
Underground placement of main power source to building pros/cons?
Pro: Best for urban areas, for high load carrying
Con: more expensive,
General - cables are run in pipe conduit or raceways for protection
Know the way electricity flows, list out the processes
https://www.studyforfe.com/blog/fundamentals-of-single-line-diagrams/
Utility Source(company) –> Meter –>Transformer (outdoor pad/ventilated interior)–> main switchgear –> main switchboard –> panelboards –> branch circuits —> outlets/appliances
What is the purpose of a switchgear
Measures, controls and distributes the power at the main electrical panel,
It includes a main disconnect of switches, fuses, and circuit breakers protecting the electric power supply to a building (BCI 11.31)
what is a service switch?
Within the switchgear - the main disconnect for entire electrical service (BCI 11.31)
What brings power from the main panel to the subpanels
Feeder cables bring power from the main distribution panel to sub panes in large buildings
What do branch circuits do?
Branch circuits distribute power from subpanels throughout the building (BCI, 11.32)
What is the purpose of a transformer
- Transformers are typically utilized by larger building
- Used to step down from a high-supply voltage to service voltage
- Placed close to and outdoor pad or in a well ventilated room with a wall adjacent to exterior wall
Explain this diagram
main utility line enter building through cables into meter (records usage) >then into transformer > into switchgear cables that run through closet room panels that steps down power tovappliances
What is this type of distribution? Where would you see this type?
type of distribution phase:
120/240V Single phase, 3wire
Residential and small commercial bldg
What is this type of distribution? Where would you see this type?
Distribution type:
120/240V Three phase, 4wire
Commercial bldg
What is this type of distribution? Where would you see this type?
Distribution type:
three phase 4 wire (wye connected)H
Large commercial
Electrical operating cost in a single tenant commercial building can be minimizes by using which of the following techniques? Choose the four that apply
A. Daylighting
B. Indirect lighting
C. Load control
D. Multiple metering
E. Occupancy sensors
F. Light emitting diode lamps (LED)
(ballast Ch 17)
A. Daylight
used to reduce the amount if electrical lighting needed
C. Load control
A way to avoid peaking demand electrical charges by automatically or manually shutting off nonessential before peak demand
E. Multiple metering
Used for multitenant spaces would not reduce savings for commercial bld but does per individual tenant or they only are charge what they use not what others use
F. Light emitting diode lam LED
Minimize power required
High voltages are used in commercial buildings because
A. Conductors and conduit can be smaller
B. A wider variety of loads can be accommodated
C. Commercial buildings require more power
D. Transformers can step down the voltages to whatever is required
(ballast Ch 17)
A. Conductors and conduit can be smaller
- as voltages increase, current may be decreased and the system will still provide the same amount of power
- lower currents require smaller conductors
- for large commercial buildings smaller conductors means less expense in conductors and conduit as well as easier installation on smaller wires
Which would be the best location for a transformer for a larger school building?
A. On the power pole serving the building.
B. In a separate room near the exterior
C. Outside on a transformer pad close to the main switchgear
D. In a protective shed where power from the utility company enters the property
B. In a separate room near the exterior
- best for protection, ventilation and ease of installation and removal.
- large school would require voltage service service and step down transformers provided by owner
- having it on a pad outside would expose it to weather and vandalism
