Like any specialized field of study, electrical contracting has it own set of specialized terms. Here is a small glossary of common electrical terms that you may hear us using on the job.
110, 120, 220, 240
This refers to voltage. From a power plant or generator, electricity travels over local distribution systems to individual homes. Most houses today have two 110- or 120-volt wires and one neutral wire running into the house from the local distribution system. These wires can run underground or above ground. For example, if there are two 120-volt wires running to the house, then the house has 240-volt service and appliances, such as dryers and air conditioners.
1-, 2-, 3-, or 4-Gang
‘#-Gang’ describes the number of spaces for devices in an electrical wall box. For example, a 1-gang dimmer switch will have a single dimmer on the plate, a 2-gang dimmer switch will have 2 dimmers, and so on. Larger and more complex construction can have up to 6-gang or more!
Amp / Amperage
“Amp” is shorthand for “ampere,” which is the basic unit of measurement for electric flow. It is the rate of electron flow or current in an electrical conductor moving past a specific point in one second. If you think in terms of water through a hose, amperage would be a measure of water volume flowing through the hose.
An appliance is not a fixture (fan, light) or a device (outlet, switch), but us a non-lighting movable electrical item that comsumes electricity to function. Examples: fax machine, garbage disposal, refrigerator, toaster.
Arcing / Arc
An arc is a visible energy discharge between two terminals that is caused by electrical current interacting with gases in the air via ionization. Electric arcs occur in nature in the form of lightning.
AFCI / AFI
Arc Fault Circuit Interrupter. It is a type of circuit breaker that breaks the circuit when it detects a dangerous electrical arc. They are sometimes called “combination breakers,” because of multiple methods of arc detection. There are also AFCI outlets that serve the same purpose.
An automatic switching device that disconnects power to a circuit when current or heat exceeds a certain level for a certain amount of time. It’s located in a circuit panel box and its handle is generally in one of three positions: on, tripped (the middle position), and off.
A cable is a set of wires, usually encased in an outer protective sheath. A “cord” would be a cable by this definition, but a cord is more flexible and often has a plug end for a portable appliance or lamp. Common types of cables are for TV/satellite and audio-visual installation.
An electrical device that provides a path for electrical current to flow in (roughly) a circular line, route, or movement that starts and finishes at the same place.
A tube, made of metal, plastic or PVC, used to protect and route electrical wiring in a building or non-building structure. It can be solid or flexible.
Electricity or “current” is the movement of electrons through a conductor, like a wire. The rate of flow of electrical energy through a wire, comparable to the amount of water flowing in a pipe. The difference between alternating current (AC) and Direct current (DC) lies in the direction in which the electrons flow. In DC, the electrons flow steadily in a single direction, or “forward, while in AC, electrons keep switching directions, sometimes going “forward” and then going “backward.” We use AC currents in household applications such as fans, TVs, computer systems. It is the output of common utility outlets.
As distinct from a fixture or appliance, an item which does not itself consume significant electricity, but interrupts or passes it on in a particular fashion. Examples include: switch, receptacle, thermostat, breaker, fuse.
A device used to ensure that an electrical circuit is completely de-energized for service or maintenance. They are most often used on larger electrical units, such as electric water heaters and AC condensing units. It is a means to “disconnect” power between the item and the breaker.
A form of energy that is carried through wires and is used to operate machines, lights, etc. It is observable in nature (lightning) or is produced (generator).
In an electric power system, a fault or fault current is any abnormal electric current. A fault occurs if a circuit is interrupted by some failure in power transmission or in the actual physical pieces of the system.
An item that is non-movable (in a “fixed” position) once installed, and are normally part of the build of the home. Lights and fans are the most common types of fixtures.
Fuse / Fuse Box
An electrical safety device that can stop current from flowing if it becomes overloaded. Its safety device consisting of a strip of wire that melts and breaks an electric circuit if the current exceeds a safe level. A “fuse box” contains fuses rather than breakers; the two terms (breaker and fuse) are often confused.
GFCI / GFI
Ground Fault Circuit Interrupter. They are devices to prevent electrocution, which serves also as a receptacle. Since 1973, National Electric Code has required GFCI protection for more and more receptacle locations in homes. If connected properly, a GFCI receptacle is able to sense and disrupt ground-faults. Nowadays, for new construction, there are special breakers that are both GFCI and AFCI capable, sometimes called “dual-function breakers.”
A ground is a direct electrical connection to the earth. A “ground wire” means a separate wire that keeps metal parts of devices, fixtures, or appliances from staying accidentally energized and endangering people or equipment in the event of a surge. These wires are either bare copper or have green insulation. The ground wire is not connected so as to be part of the normal path of the circuit, but when a ground wire does carry current, it is doing it’s job by diverting power so it does not create a dangerous situation. If items are not grounded and the electricity is touched by, say your hand, your body can become a path for current from a hot wire touching the metal to get to the ground.
A ground fault occurs when a short circuit finds a path to the earth via something besides the neutral/ground wire. It is a “leaking” of current off of the intended path. The electrical current taking an alternative path to the ground through the user. Most shocks are an example of a ground fault.
Also known as “live” wire. Electric wire or cable through which current is flowing, as opposed to ground wire or neutral wire.
A container for electrical connections, usually intended to conceal them from sight, deter tampering, and to withstand weather. They can be in many types of locations: inside walls, ceilings, attics, and outside.
The amount of power consumed by a circuit, measured in amps.
The neutral wire is a circuit conductor that normally carries current, and is connected to ground (earth) at the main electrical panel.
Overheat / Overload
Overheating is when the wires become too hot to be safe, and the breaker trips to prevent damage. An overload occurs when a circuit has carried a little too much energy for too long, OR too much energy in a very short span of time.
The large metal box containing breakers for circuits; other names include circuit panel, breaker panel, or breaker box. The “main” panel or “service” panel would be the central source for the home and would be receiving its power from the power company; it’s normally located near your electric utility meter (older homes it may be on an interior wall adjacent to the meter). There can be subpanels in a home, fed from the main panel and containing some of the home’s circuit breakers – these are usually the panels you’d find in your garage or a hallway.
“Receptacle” is mostly a fancy word for “outlet.” A device that serves as the outlet for lights or appliances to connect to a circuit by means of a cord with a plug on the end. Sometimes the word “plug” is used to mean “outlet”, but that is inaccurate; the plug is the end piece of a wire from an appliance or other electrical item that connects TO an outlet.
A short circuit occurs when a “hot” wire and a “neutral” wire touch each other. When this happens, a large amount of current flows, causing a fuse to blow or a circuit breaker to trip, potentially creating sparks or a pop that can create smoke. The cause of this unfortunate occurrence may be as simple as a loose connection on one of these two wires in a junction box.
The part of a light fixture that receives the bulb or tube. It is not the same as a plug or receptacle.
Splicing wire is the process of joining two or more pieces of wire together. Leave this kind of work to a professional, or you may risk a short.
A device used to interrupt current to part of a circuit. You use one to turn lights off and on.
A point where two or more wires are connected in an electrical circuit (which can be a screw or other pressure-device), for the purpose of passing electrical current along.
If you have 2 switches that control 1 light, you have a 3-way system. The name comes from the number of terminals on or contact points within the switches involved. 4-way systems exist as well.
Volt / Voltage
Voltage is a force that makes electricity move through a wire.
Watt / Wattage
The amount of power required to operate an electrical appliance or device. Wattage is directly proportional to current and to voltage and is mathematically the product of them (amps times volts). It’s like horsepower.