Electrician Apprentice HQ #1 Online Resource For Becoming An Electrician 
Last updated on February 27th, 2024.
As you progress in the electrical trade you’ll hear a bunch of electrical terms and definitions being tossed around like their common knowledge.
It takes years to get a firm understanding of all these electrical terms.
Unless… you find a guide online that summarised all the definition into a single post ????️
And that’s exactly what I’ve done here.
This is the list of electrical terminology that I wish I had when I started my electrician apprenticeship.
Let’s jump right into the full list of electrical terms and definitions ????????
Electrical Terms For Circuits
AC (Alternating Current) — AC stands for Alternating Current. This is an electric current that reverses its direction many times a second at regular intervals.
DC (Direct Current) — DC stands for Direct Current. DC current is an electric current that flows in only one direction.
Feeder – All circuit conductors between the service equipment, the source of a separately derived system, or other power supply source and the final branch-circuit overcurrent device.
Feeder Pillar – Feeder pillar, or what some call power boxes, play a pivotal role in managing electrical systems. They’re not just cabinets; they centralize control, efficiently distributing power across multiple circuits. This makes troubleshooting and upgrades much simpler and safer.
Fuse — A circuit interrupting device consisting of a strip of wire that melts and breaks an electric circuit if the current exceeds a safe level. To restore service, the fuse must be replaced using a similar fuse with the same size and rating after correcting the cause of failure.
Ground or Earth — The reference point in an electrical circuit from which voltages are measured, a common return path for electric current, or a direct physical connection to the Earth.
Ground Fault – An unintentional, electrically conductive connection between an ungrounded conductor of an electrical circuit and the normally non–current-carrying conductors, metallic enclosures, metallic raceways, metallic equipment, or earth.
Grounded Conductor – A system or circuit conductor that is intentionally grounded.
Grounded (Grounding) – Connected (connecting) to the ground or to a conductive body that extends the ground connection.
Ground Fault – Think of a ground fault as an unexpected detour for electricity, where it veers off its intended path and touches parts it shouldn’t. This not only poses a risk of shock but can also lead to equipment damage, emphasizing the need for proper grounding in safety protocols.
An electrician’s toolkit isn’t complete without a electrical knockout set, the go-to for creating precise holes in panels or boxes. Its versatility comes from the variety of sizes it offers, making it indispensable for installations and modifications. Plus, the manual operation with a socket wrench adds a touch of craft to the job.
Load — Anything which consumes electrical energy, such as lights, transformers, heaters and electric motors.
Neutral Conductor – The conductor connected to the neutral point of a system that is intended to carry current under normal conditions.
Overload – Operation of equipment in excess of normal, full-load rating, or of a conductor in excess of rated ampacity that, when it persists for a sufficient length of time, would cause damage or dangerous overheating. A fault, such as a short circuit or ground fault, is not an overload.
Parallel Circuit — A circuit in which there are multiple paths for electricity to flow. Each load connected in a separate path receives the full circuit voltage, and the total circuit current is equal to the sum of the individual branch currents.
Rectifier — An electrical device that converts an alternating current into a direct one by allowing a current to flow through it in one direction only. There are both half wave rectifiers and full wave rectifiers.
Series Circuit — A circuit in which there is only one path for electricity to flow. All of the current in the circuit must flow through all of the loads completing its path to the source of supply.
Series Parallel Circuit — An electric current containing groups of parallel-connected receptive devices, the groups being arranged in the circuit in series; a series multiple circuit.
Short Circuit — A fault in an electric circuit or apparatus due usually to imperfect insulation, such that the current follows a by-path and inflicts damage or is wasted.
Electrical Terms for Components
Ammeter — Measures the current flow in amperes in a circuit. An ammeter is connected in series in the circuit (unless using a clamp meter)
AFCI (Arc Fault Circuit Interrupter) – An arc fault circuit interrupter is a special type of receptacle or circuit breaker that opens the circuit when it detects a dangerous electrical arc. It’s used to prevent electrical fires.
Capacitor – A passive two-terminal electrical component used to store electrical energy temporarily in an electric field.
Circuit — A closed path in which electrons from a voltage or current source flow. Circuits can be in series, parallel, or in any combination of the two.
Circuit Breaker — An automatic device for stopping the flow of current in an electric circuit. To restore service, the circuit breaker must be reset (closed) after correcting the cause of the overload or failure.
Conductor — Any material where electric current can flow freely. Conductive materials, such as metals, have relatively low resistance. Copper and aluminum wire are the most common conductors used in the electrical trade.
DMM (Digital Multimeter) – A digital multimeter stands as the Swiss Army knife for electricians, capable of gauging voltage, current, and much more with precision. Mastering its use not only enhances your troubleshooting skills but also ensures your projects meet the highest safety standards.
Diode — A diode is a semiconductor device with two terminals, typically allowing the flow of current in one direction only.
Generator – A device that converts mechanical energy to electrical energy for use in an external circuit. The source of mechanical energy may vary widely from a hand crank to an internal combustion engine. Generators provide nearly all of the power for electric power grids.
GFCI (Ground Fault Circuit Interrupters) — A GFCI outlet is a device intended for the protection of personnel that functions to de-energize a circuit or portion thereof within an established period of time when a current to ground exceeds some predetermined value that is less than that required to operate the overcurrent protective device of the supply circuit.
Inverter — An apparatus that converts direct current into alternating current.
Insulator — Any material where an electric current does not flow freely. Insulating materials, such as glass, rubber, air, and many plastics have relatively high resistance. Insulators protect equipment and life from electric shock.
Service — The conductors and equipment used to deliver energy from the electrical supply system to the system being served.
Service Lateral – The underground service conductors between the street main – including risers – and the first point of connection to the service-entrance conductors in a terminal box (also known as a junction box), meter, or other enclosure.
Semiconductor — A solid substance that has a conductivity between that of an insulator and that of most metals, either due to the addition of an impurity or because of temperature effects. Devices made of semiconductors, notably silicon, are essential components of most electronic circuits.
SCR (Solid State Relay) – An electronic switching device that switches on or off when a small external voltage is applied across its control terminals. The switching action happens extremely fast.
Solenoid — A solenoid transforms electric current into magnetic action, much like magic. This coiled wire becomes a magnet when powered, opening a world of possibilities, from starting your car to controlling hydraulic pumps. It’s a cornerstone in making modern machinery move.
Switch — A switch is a device for making, breaking, or changing the connections in an electric current.
Switchgear – The combination of electrical disconnect switches, fuses or circuit breakers used to control, protect, and isolate electrical equipment. Switchgear is used both to de-energize equipment to allow work to be done and to clear faults downstream.
Transistor — A semiconductor device with three connections, capable of amplification in addition to rectification.
Electrical Terms for Mathematical Calculations
Apparent Power — Measured in volt-ampers (VA). Apparent power is the product of the rms voltage and the rms current.
Ampere (A) — A unit of measure for the intensity of an electric current flowing in a circuit. One ampere is equal to a current flow of one coulomb per second.
Capacitance — The ability of a body to store an electrical charge. Measured in farads as the ratio of the electric charge of the object (Q, measured in coulombs) to the voltage across the object (V, measured in volts).
Current (I) — The flow of an electric charge through a conductor. An electric current can be compared to the flow of water in a pipe. Measured in amperes.
Demand — The average value of power or related quantity over a specified period of time.
Farad — A unit of measure for capacitance. One farad is equal to one coulomb per volt.
Frequency — The number of cycles per second. Measured in Hertz. If a current completes one cycle per second, then the frequency is 1 Hz; 60 cycles per second equals 60 Hz.
Henry — A unit of measure for inductance. If the rate of change of current in a circuit is one ampere per second and the resulting electromotive force is one volt, then the inductance of the circuit is one henry.
Hertz — A unit of measure for frequency. Replacing the earlier term of cycle per second (cps).
Impedance (Z) – The effective resistance of an electric circuit or component to alternating current (AC), rising from the combined effects of ohmic resistance and reactance.
Inductance (H) — The property of a conductor by which a change in current flowing through it induces (creates) a voltage (electromotive force) in both the conductor itself (self-inductance) and in any nearby conductors (mutual inductance). Measured in henry (H).
Kilowatt-hour (kWh) — The product of power in kW and time in hours. Equal to 1000 Watt-hours. For example, if a 100W light bulb is used for 4 hours, 0.4 kWhs of energy will be used (100W x 1kW / 1000 Watts x 4 hours). Electrical energy is sold in units of kWh.
Kilowatt-hour Meter — A device used to measure electrical energy use.
Kilowatt (kW) — Equal to 1000 watts.
Lenz Law – Lenz law is a little bit more on the technical side, but one of the electrical engineers you work with might bring it up (they like to flash their fancy words). Lenz’s law states that the direction of the current induced in a conductor by a changing magnetic field (as per Faraday’s law of electromagnetic induction) is such that the magnetic field created by the induced current opposes the initial changing magnetic field which produced it.
I realize that can sound like a lot of gobbledygook. But it’s essentially just a rule that tells you which way the current will flow when you stick a conductor (like a metal coil) inside a magnetic field. The images shown over at Electrical4U can make it a lot easier to understand.
Ohm — (Ω) A unit of measure of resistance. One ohm is equivalent to the resistance in a circuit transmitting a current of one ampere when subjected to a potential difference of one volt.
Ohm’s Law — The mathematical equation that explains the relationship between current, voltage, and resistance (V=IR).
Power — The rate at which electrical energy is transferred by an electric circuit. Measured in Watts.
Reactive Power — Reactive power is the portion of electricity that establishes and sustains the electric and magnetic fields of AC equipment. Exists in an AC circuit when the current and voltage are not in phase. Measured in VARS.
Resistance (Ω Ohms) — The opposition to the passage of an electric current. Electrical resistance can be compared to the friction experienced by water when flowing through a pipe. Measured in ohms.
Admittance (Ω Ohms) — Admittance is essentially the opposite of resistance (and is given by 1 divided by the resistance). It is the measure of the flow of current which is allowed by a device or a circuit.
True Power — Measured in Watts. The power manifested in a tangible forms such as electromagnetic radiation, acoustic waves, or mechanical phenomena. In a direct current (DC) circuit, or in an alternating current (AC) circuit whose impedance is a pure resistance, the voltage and current are in phase.
VARS — A unit of measure of reactive power. Vars may be considered as either the imaginary part of apparent power or the power flowing into a reactive load, where voltage and current are specified in volts and amperes.
Volt-Ampere (VA) — A unit of measure of apparent power. It is the product of the rms voltage and the rms current.
Volt (V) — A unit measure of voltage. One volt is equal to the difference of potential that would drive one ampere of current against one-ohm resistance.
Voltage (E) — An electromotive force or “pressure” that causes electrons to flow and can be compared to water pressure which causes water to flow in a pipe. Measured in volts.
Watt-hour (Wh) — A unit of electrical energy equivalent to power consumption of one watt for one hour.
Watt (W) — A unit of electrical power. One watt is equivalent to one joule per second, corresponding to the power in an electric circuit in which the potential difference is one volt and the current one ampere.
Electrical Terms For Conduit Bending
Hand Bender – A tool used for bending EMT (electrical metal tubing), IMC (intermediate metal conduit), and RMC (rigid metal conduit). HAnd benders come in sizes: 1/2″, 3/4″, 1″, and 1-1/4″
Four Bend Saddle – Four bends in a piece of conduit that clears and obstacle by saddling it.
Offset – A bend in conduit to clear an obstacle. Typically only two bends.
Three Bend Saddle – Three bends in a piece of conduit – one in the center and two side bends that clear an obstacle by “saddling” it.
Gain – The difference between the sum of the straight distances and the actual length of the conduit (how much the conduit will grow after being bent).
Shrink – The amount the conduit will “shrink” because of bending around an obstruction – picture an inchworm and how it shrinks when it moves. Shrink is added to the overall distance to the obstruction to compensate before bending.
Multiplier – Used to calculate the distance between bends using “multiplier X offset”
Random Electrical Terms That You Should Be Familiar With
Arc Flash – An arc flash is light and heat and is a type of electrical explosion or discharge that results from a low-impedance connection through air to ground or another voltage phase in an electrical system. Arc flash temperatures can reach or exceed 35,000 °F
Arc Blast – The intense heat from an arc causes sudden expansion of air resulting in a blast. Copper expands during an arc flash event at a factor of 67000 times within a few milliseconds.
Calorie — The French heat unit. Used to measure energy levels for Arc Flash boundaries and proper PPE when working on energized electrical equipment.
CE (Construction Electrician) – Construction electricians can perform those basic tasks with little or no supervision, though they can’t act as a foreman or supervise other workers.
Once you’ve finished memorizing all the electricity terminology, the next step is American Job Site Slang.
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