206-Power Flashcards
What is the main consideration in determining wire size
Amp draw
How is 277 V picked up
One leg to neutral in a 460 V system
What is the advantage of a 460 V system over a 238 V system
Uses less current and can use smaller wire
How can a delta with neutral system be detected
The high leg reads 195 to 213 to ground
How can a wye with neutral system be detected
All legs read the same
What has to be used when connecting aluminum wire
Oxidation paste and split bolt
What are the three disadvantages of aluminum wire
Corrodes easily, contracts and expands, have to use at least one size larger than copper wire
How is wire size for motors
Manufacturers specifications or 125% of the rated FLA/RLA
Name the four voltage currents commonly deliver today
115/230V single phase
208V 3 phase
240V 3 phase
460V 3 phase
What is the popular name for nonmetallic sheathed cable
Romex
By NEC standards what is the grounding conductor
It connects equipment to ground for safety
Number 10 wire can carry how many amps
30 A
What is 460 V single phase used for
Condenser fan motors on rooftops
What is a grounded conductor by the NEC
A neutral current carrying conductor
What does the term phase of an AC circuit refer to
The number of currents alternating at different time intervals through a load
What are triple pole breakers
Breakers for three phase
Number six wire can carry how many amps
55 to 60 A
Number 12 can carry how many amps
20 A
What voltage is commonly brought to a residence
115 V 230 V single phase
What is 277 V used for
Commercial lighting and hotel PTAC systems
Number 14 wire can carry how many amps
15 A
What might you do in a situation where there is no spare opening in a breaker panel for installation of equipment
Use mini breakers, slimline or piggyback
What are the two failures of breakers and how are they found
Won’t pass voltage or lowers the voltage. Trips below the rated amperage
Where are single pole breakers used and what is their voltage
In residential areas, 115 V
Number eight wire can carry how many amps
40-45 A
What does the term hertz mean
Cycles per second
How is 460 V single phase picked up
Between any two of the hot legs in a 460 V system
What is the voltage of double pole breakers
230 V
What are the two types of electrical disconnect switches
Fused and nonfused
What is the popular name for underground nonmetallic sheathed cable
Underground feeder
