A 24-ohm heating element is connected across a 120-volt source. What is the current?
General Electrical Knowledge
Question · Easy
14 on 15, 12 on 20, 10 on 30
Short
A conductor carrying 10 amperes has 2 ohms of resistance. How much heat power is produced in that conductor?
In a series circuit, which quantity is the same through every component?
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Which identification is required for an equipment grounding conductor that is not bare?
What is the standard frequency of alternating-current utility power in the United States?
Same battery. Which lets more through?
The peak value of a 120-volt RMS sine-wave voltage is closest to which of the following?
What is the primary electrical function of a rectifier used on an impressed-current cathodic-protection system?
Which instrument is used to measure insulation resistance of a cable or winding, typically in megohms?
A Class A ground-fault circuit interrupter is designed to trip when ground-fault current is in which range?
Two 12-ohm resistors are connected in parallel. What is the equivalent resistance?
Question · Medium
A balanced 480-volt, three-phase load draws 20 amperes per phase at 0.85 power factor. What is the true power, nearest the listed value?
A 30 kVA single-phase transformer is rated 480 volts primary and 120 volts secondary. What is the full-load secondary current?
Using VD = 2KIL / CM with K = 12.9 for copper, what is the one-way voltage drop on a 120-volt single-phase circuit that carries 16 amperes for 80 feet on 12 AWG copper (6,530 circular mils)?
Compared with copper of the same AWG size, an aluminum current-carrying conductor has which property?
Power factor of an AC circuit is defined as which ratio?
Four identical 12-volt batteries are connected in series. What is the nominal string voltage, and what happens to ampere-hour capacity compared with one battery?
A clamp-on ammeter measures AC current by sensing which quantity around the conductor?
What is the circular-mil area of a solid conductor that is 1/4 inch in diameter?
One mechanical horsepower is equal to which electrical power?
Inductive reactance of a coil is XL = 2πfL. If frequency doubles and inductance stays the same, what happens to XL?
A transformer has a 4:1 primary-to-secondary turns ratio. If 480 volts is applied to the primary, what is the secondary voltage (ideal transformer)?
Which statement correctly describes electron flow in a metallic conductor?
A 10-horsepower motor is 90 percent efficient. What is the approximate electrical input power?
Which lockout/tagout action is required before working on a cathodic-protection rectifier or a lightning-protection bonding connection that can be energized?
Using VD = 1.73KIL / CM with K = 12.9, what is the voltage drop on a 208-volt, three-phase copper feeder carrying 40 amperes for 150 feet on 4 AWG (41,740 circular mils)?
Question · Hard
A 15 kVA transformer is connected 480 volts delta primary and 208Y/120 volts secondary. What is the full-load secondary line current?
An 8-ohm resistor and a 24-ohm resistor are in parallel. That combination is in series with a 6-ohm resistor across 120 volts. What is the source current?
A rectifier input is 12 kVA at 0.80 lagging power factor. What are the true power and the reactive power?
Why do lightning-protection main conductors use large-strand cables rather than a single small solid wire of equal DC resistance?
Using VD = 2KIL / CM with K = 12.9, what is the voltage drop on a 240-volt single-phase copper circuit carrying 100 amperes for 250 feet on 1/0 AWG (105,600 circular mils)?
NEC Article 100 defines the service point as which of the following?
National Electrical Code
In NEC terms, which statement best distinguishes grounding from bonding?
Which of the following is not permitted to be used as a grounding electrode under NEC 250.52(B)?
NEC 250.106 requires which connection when a lightning protection system is installed?
According to NEC 250.60, air-terminal conductors and their driven electrodes shall not be used in which way?
NEC 240.4(D) generally limits a 12 AWG copper conductor to which maximum overcurrent-device rating?
In the 2020 NEC adopted by NMAC 14.10.4, which article covers overvoltage protection, including surge-protective devices rated 1,000 volts or less and surge arresters over 1,000 volts?
NEC 110.26(A)(2) requires the width of the working space in front of electrical equipment to be the width of the equipment or not less than which dimension, whichever is greater?
A Type 1 surge-protective device is permitted to be installed in which location?
A single rod, pipe, or plate electrode that does not have a resistance to earth of 25 ohms or less must be supplemented by an additional electrode under which NEC rule?
Where more than one rod, pipe, or plate electrode is used for a grounding electrode system, NEC 250.53(B) requires them to be spaced at least how far apart?
Which installation qualifies as a concrete-encased electrode under NEC 250.52(A)(3)?
A 200-ampere service uses 3/0 AWG copper ungrounded service-entrance conductors. What is the minimum copper grounding electrode conductor required by NEC Table 250.66 (before any electrode-type cap)?
Where the grounding electrode conductor connects only to a rod, pipe, or plate electrode, NEC 250.66(A) does not require that conductor to be larger than which size?
What is the minimum copper equipment grounding conductor for a 200-ampere overcurrent device under NEC Table 250.122?
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