AL Electrician key terms

The organization, office, or individual responsible for enforcing the code and approving equipment, materials, installations, and procedures. Inspectors, fire marshals, and building officials commonly act as the AHJ for electrical work.

Equipment or material that has been evaluated by a nationally recognized testing laboratory and found to meet a designated standard. Listing means the product is suitable for its intended use when installed per instructions and the code.

An installation area subject to saturation with water or other liquids, such as outdoors in direct weather, car washes, and wash-down areas. Wet-location wiring methods and fittings must be listed for that use.

An enclosed channel of metal or nonmetallic material designed expressly for holding wires, cables, or busbars. Common examples are conduit, tubing, and wireways used to route and protect conductors.

A factory assembly of two or more insulated conductors, with or without a grounding conductor, enclosed in an overall nonmetallic sheath. It is permitted only in specific occupancies and must be protected where subject to physical damage.

A thin-wall metal raceway with a galvanized or otherwise protected finish, recognized for use in most dry and damp interior locations. EMT must be secured and supported at required intervals and needs fittings listed for the application.

A heavy-wall threaded metal raceway permitted indoors, outdoors, underground, and in many corrosive or hazardous areas. Its thickness gives high mechanical protection and it can serve as an equipment grounding conductor when properly installed.

Any current in excess of the rated current of equipment or the ampacity of a conductor. It may result from overload, short circuit, or ground fault, and must be interrupted before conductors or equipment are damaged.

The conductive path installed to connect normally non-current-carrying metal parts of equipment together and to the system grounded conductor or grounding electrode. It provides a low-impedance fault path that lets overcurrent devices clear faults quickly.

A system or circuit conductor that is intentionally connected to earth, commonly called the neutral on a grounded system. It carries return current during normal operation and is insulated with a white or gray finish.

The permanent joining of metallic parts to form an electrically conductive path that ensures electrical continuity and capacity to conduct any fault current safely. Bonding is distinct from grounding, which connects the system to earth.

A device that monitors the difference between current leaving and returning on a circuit and trips when that imbalance reaches roughly 4 to 6 milliamps. It protects people from shock in bathrooms, kitchens, outdoors, and other specified areas.

A device intended to detect the signature of a dangerous arcing fault in branch-circuit wiring and open the circuit. It is required for dwelling-unit bedroom and other specified branch circuits to reduce the risk of fire.

The highest current a device is rated to safely interrupt at a stated voltage without damage or hazard. A fuse or circuit breaker must have an interrupting rating at least equal to the available fault current at its line terminals.

The overhead conductors that run from the utility's last pole or transformer to the service point on a building. These conductors are owned and maintained by the utility, not the electrical contractor.

The underground conductors that run from the utility's supply system to the service point of a building. Like a service drop, it is supplied by the utility and ends where the customer's service equipment begins.

All circuit conductors between the service equipment, source of a separately derived system, or other power supply and the final branch-circuit overcurrent devices. Feeders carry the total load of the branch circuits they supply.

The circuit conductors between the final overcurrent device protecting the circuit and the outlets or equipment served. Branch circuits feed lighting, receptacles, and individual appliances at their point of use.

A load expected to operate at maximum current for three hours or longer. The conductor and overcurrent device for a continuous load must be sized at 125 percent of the load unless the code allows otherwise.

The ratio of the maximum demand on a system, or part of it, to the total connected load of that system or part. Applying demand factors keeps feeder and service sizes reasonable because not all loads run at once.

A branch circuit made of two or more ungrounded conductors with different voltage-to-ground values and a single shared grounded conductor. Its ungrounded conductors must be disconnected simultaneously by a common handle or tie bar.

The current value taken from the code tables for a motor of a given horsepower, voltage, and type. It is used to size conductors, overload protection, and disconnects rather than the nameplate current on the motor.

A device that protects the motor against overheating from excessive current that is below the level of a short circuit or ground fault. It is typically set at roughly 115 to 125 percent of the motor full-load current.

A device that transfers electrical energy between circuits through magnetic induction, changing voltage and current in proportion to its turns ratio. Transformers may be dry-type or liquid-filled and are rated in kilovolt-amperes.

An area where fire or explosion hazards exist because of flammable gases, vapors, combustible dusts, fibers, or flyings. Wiring methods and equipment must be specially listed and installed per the class, division or zone, and group.

The maximum current, in amperes, a conductor can carry continuously under the conditions of use without exceeding its temperature rating. Ampacity is affected by conductor size, insulation type, ambient temperature, and bundling.

The loss of voltage along a circuit caused by the resistance and reactance of its conductors. Excessive drop at the load can cause poor performance and overheating and is commonly limited by design to a few percent.

The amount of a raceway's cross-sectional area occupied by conductors, usually limited to 40 percent when three or more conductors are installed. Fill limits allow conductors to be pulled without damage and to dissipate heat.

The total volume a box must provide for its conductors, devices, clamps, and grounding conductors, counted in cubic inches per item. Each conductor size is assigned a volume allowance based on the largest conductor in the box.

The relationship showing that voltage equals current multiplied by resistance, written as E = I x R. Any one value can be found from the other two, making it basic to troubleshooting and circuit calculations.

The safety practice of de-energizing equipment, applying a personal lock, and attaching a warning tag before work begins. It prevents accidental re-energization and is required by workplace safety rules for servicing equipment.

A test instrument that applies a high direct voltage to insulation and measures its resistance, usually in megohms. It is used to check motors, cables, and transformer windings for moisture, age, or damage.

The clear space required in front of electrical equipment so it can be safely worked on while energized. It is generally at least 30 inches wide, 36 inches deep, and 6-1/2 feet high, with greater depth at higher voltages.

A sudden, explosive release of energy caused by an arcing fault between energized conductors or to ground. It produces intense heat, light, and pressure, and workers must use rated personal protective equipment based on incident energy.

The state agency that licenses electrical contractors in Alabama, administers the licensing examination, and enforces the statutes and rules governing electrical contracting. Licensees must renew and meet the board's continuing education requirements.

A written modification to a construction contract that changes the scope, price, or schedule of the work. It must be signed by authorized parties before the changed work proceeds so payment disputes are avoided.

A percentage of each progress payment withheld by the owner or general contractor until the project is substantially or finally complete. It protects the payer against unfinished or defective work and is released per the contract terms.

A legal claim filed against a property by a contractor or supplier who has not been paid for labor or materials furnished to improve it. Strict deadlines and notice requirements apply, and the lien can cloud the property title.