# Glossary for Electrical Exams for Contractor Licensing

- Alternating Current (AC)
- It is a type of electrical current, in which the direction of the flow of electrons switches back and forth at regular intervals or cycles.
- Amperes
- Amperes is the unit used to measure electric current.
- Apparent Power
- True power is called apparent power, and it is the product of a circuit's voltage and current, without reference to the phase angle.
- Capacitance
- Capacitance is the ratio of the change in an electric charge in a system to the corresponding change in its electric potential.
- Capacitive Reactance
- Capacitive Reactance is the internal resistance of the capacitance to the alternating current.
- Circular Mills
- Circular Mills is a unit of area, equal to the area of a circle with a diameter of one mil.
- Conductor
- Conductor is an object or type of material that allows the flow of electrical current
- Current
- Current is the rate at which an electric charge flows in a conductor.
- Current-Flow Path
- Current-Flow Path is the path through which current flows within a circuit
- Closed circuit
- Closed Circuit means a complete electrical connection around which current flows or circulates.
- Common Denominator
- Common denominator is a feature shared by all members of a group.
- Delta Connected Systems
- Electrical Distribution systems do not contain a nuetral.
- Direct Current (DC)
- Direct Current (DC) is the constant flow of Electric Charge from high to low Potential.
- Distribution (Electric Power Distribution)
- Distribution (Electric Power Distribution) is the final stage in the delivery of electric power; it carries electricity from the transmission system to individual consumers.
- Distribution Transformers A distribution transformer or service transformer is a transformer that provides the final voltage transformation in the electric power distribution system, stepping down the voltage used in the distribution lines to the level used by the customer.
- Distribution Substation
- Distribution Substation is a part of an electrical generation, transmission, and distribution system.
- Distribution Systems
- It can be defined as the sequential flow of procedures, systems, and activities that are designed and linked to facilitate and monitor the movement of goods and services from the source to the consumer.
- Electromechanical relays Electromechanical relays are electrically operated switches used to isolate circuits or batteries, detect faults on transmission and distribution lines, and control a high powered circuit using a low power signal.
- Farads
- Farads is the SI derived unit of electrical capacitance, the ability of a body to store an electrical charge.
- Feeders
- Feeders is a piece of industrial control equipment used to deliver solid material at a known rate into some process.
- Frequency
- Generally refers to a voltage that is changing in the form of a sine wave.
- Henry
- Henry is the SI unit of inductance and it symbol is H.
- Horsepower
- Horsepower is a measure of power, and voltage measures the amount of energy carried in a circuit.
- Impedance
- Impedance is the measure of the opposition that a circuit presents to a current when a voltage is applied.
- Inductance
- It is the tendency of an electrical conductor to oppose a change in the electric current flowing through it.
- Inductive Reactance
- Inductive Reactance is defined as the opposition to current flow. It is the reaction of the inductor to the changing value of alternating current.
- Inverse
- Opposite or contrary in position, direction, order, or effect.
- Inverse Resistance
- The electrical resistance of an object is a measure of its opposition to the flow of electric current. The inverse quantity is electrical conductance and is the ease with which an electric current passes.
- Kilowatts
- This unit is typically used to express the output power of engines and the power consumption of electric motors, tools, machines, and heaters. It is also a common unit used to express the electromagnetic power output of broadcast radio and television transmitters.
- Mixed Circuit
- Mixed Circuit is the one that has a "combination" of series and parallel paths for the electricity to flow.
- NC Contact in a relay
- NC Contact in a relay is normally closed.
- NEC
- National Electrical Code
- NO Contact in a relay
- NO Contact in a relay is normally open.
- Numerator
- The number above the line in a common fraction showing how many of the parts indicated by the denominator are taken.
- Ohms
- The Ohm is the SI unit of electrical resistance. One ohm is the resistance in a circuit transmitting a current of one ampere when subjected to a potential difference of one volt.
- Ohms Law
- It is a law stating that electric current is proportional to voltage and inversely proportional to resistance.
- Open circuit
- Open circuit an electrical circuit in which the continuity is broken so that current does not flow.
- Parallel Circuit
- A parallel circuit is a closed circuit in which the current divides into two or more paths before recombining to complete the circuit.
- Phase (Electrical Phase)
- A phase is a relative displacement between waves having the same frequency.
- Power
- The rate at which the work is being done in an electrical circuit is called electric power.
- Power Factor
- Power Factor is the relationship (phase) of current and voltage in AC electrical distribution systems.
- Primary Distribution Feeders
- Primary feeders are conductors within the distribution system which connect from the distribution sub-station and transfer power to the distribution centers.
- Primary Distribution System Consist of feeders that deliver power from distribution substations to distribution transformers. A feeder usually begins with a feeder breaker at the distribution substation.
- Primary Distribution Transformers
- Primary Distribution Transformers is straightforward: to step down the voltage and provide isolation between primary and secondary.
- Radical Distribution System
- A system whereby power is received at the utility supply voltage level by a single, incoming substation.
- Reactance
- Reactance is the opposition of a circuit element to a change in current or voltage, due to that element's inductance or capacitance.
- Reactive Power
- Reactive Power is the resultant power in watts of an AC circuit when the current waveform is out of phase with the waveform of the voltage, usually by 90 degrees if the load is purely reactive, and is the result of either capacitive or inductive loads.
- Relay
- Relay is a solenoid set up to actuate switch contacts when its coil is energized.
- Resistance
- It is a measure of the opposition to current flow in an electrical circuit.
- Resistor
- A resistor is a passive two-terminal electrical component that implements electrical resistance as a circuit element.
- Ring Main Distribution System
- Ring Main Distribution System is a method of the power distribution system, in which different parts of the power distribution network (or each load center) have an option to feed power from the same source through more than one route.
- Secondary Transmission System
- A low-voltage network or secondary network is a part of electric power distribution which carries electric energy from distribution transformers to electricity meters of end customers.
- Series Circuit
- A series circuit is a closed circuit in which the current follows one path, as opposed to a parallel circuit where the circuit is divided into two or more paths.
- Single-phased Circuits
- Single-phased Circuits is power systems are defined by having an AC source with only one voltage waveform.
- Solid-State Relays
- Solid-state relays are an electronic switching device that switches on or off when a small external voltage is applied across its control terminals.
- State of a relay
- State of a relay is open a closed.
- Substation
- Substation is a part of an electrical generation, transmission, and distribution system
- Trigonometry is used to show how stress and force are directed along with supports that are not vertical or horizontal.
- True Power
- The actual amount of power being used, or dissipated, in a circuit is called true power, and it is measured in watts.
- Voltage (Electromotive Force)
- An electromotive force or potential difference expressed in volts.
- Voltage Drop
- Voltage drop is defined as the amount of voltage loss that occurs through all or part of a circuit due to impedance.
- Volts
- The volt is the SI unit of electromotive force. One volt is the difference of potential that would allow one ampere of current to go through one ohm of resistance.
- Wattmeter
- It is an instrument for measuring the electric power (or the supply rate of electrical energy) in watts of any given circuit.
- Wye Connected Systems
- Electrical Distribution Systems which contain a neutral.