DE Electrician key terms

The maximum continuous current, in amperes, that a conductor or cable can carry under stated conditions without exceeding its temperature rating. It depends on conductor size, insulation type, ambient temperature, and how many current-carrying conductors share a raceway.

The relationship stating that voltage equals current multiplied by resistance (E = I × R). It lets an electrician calculate an unknown value when the other two are known, and it underlies voltage drop and load calculations on the job.

The ratio of real power in watts to apparent power in volt-amperes in an alternating-current circuit. A value below one means current and voltage waveforms are out of phase, so more current flows than the useful load alone would require.

Electrical power delivered by three conductors whose voltages are offset by 120 electrical degrees. For a balanced load, real power equals the square root of three times line voltage times line current times power factor.

A transformer or motor winding arrangement in which one end of each of three coils joins at a common neutral point. Line-to-neutral voltage is the line-to-line voltage divided by the square root of three, and a grounded neutral is often available.

A winding arrangement in which three coils form a closed loop, with each pair joined end to end. Line voltage equals coil voltage, line current is the square root of three times coil current, and no neutral point exists unless one winding is center-tapped.

A circuit in which current has only one path, so the same current flows through every component. Total resistance is the sum of individual resistances, and the source voltage divides among the loads in proportion to their resistance.

A circuit in which two or more paths connect across the same two points, so voltage across each branch is equal. Total current is the sum of branch currents, and total resistance is always less than the smallest branch resistance.

The property of a coil that opposes any change in current by storing energy in a magnetic field. It causes current to lag voltage in alternating-current circuits and produces inductive reactance measured in ohms.

The ability of two separated conductors to store electric charge, measured in farads. In alternating-current circuits it causes current to lead voltage and produces capacitive reactance that falls as frequency rises.

The total opposition to alternating current flow in a circuit, combining resistance and reactance as a vector quantity and measured in ohms. It determines current when an alternating voltage is applied to a reactive load.

The loss of voltage along conductors caused by their resistance and reactance while carrying current. Excessive drop causes dim lights, overheated motors, and unreliable equipment operation, so feeders and branch circuits are sized to limit it.

The circuit conductor that is intentionally connected to earth at the service or source. It carries return current during normal operation and is white or gray in color, unlike the equipment grounding conductor.

The conductive path that connects metal enclosures and non-current-carrying metal parts to the grounding system. It carries fault current back to the source so an overcurrent device opens, and it is green, green with yellow stripe, or bare.

The set of conductive elements in direct contact with the earth, such as ground rods, metal water pipe, and concrete-encased electrodes, that connect the electrical system to earth. It stabilizes voltage to earth and limits surges.

The conductor that connects the grounded circuit conductor or service equipment to the grounding electrode system. Its size is determined by the rating of the service or source rather than by the load.

A conductor that ensures electrical continuity between metal parts that must be electrically connected, such as around a water meter or across a removable fitting. It keeps all bonded metal at the same potential to prevent shock and arcing.

A fuse or circuit breaker that opens a circuit automatically when current exceeds its rating for a set time. It protects conductors and equipment from overheating and must be coordinated with conductor ampacity.

Unintended current flow from an energized conductor to ground through a path such as a person, water, or damaged insulation. A ground-fault circuit interrupter detects small imbalances and opens the circuit to prevent shock.

A device that compares current leaving and returning on a circuit and trips when the difference reaches a threshold, typically 4 to 6 milliamperes for personnel protection. It is required in bathrooms, kitchens, outdoors, and other wet or damp locations.

A device that senses the characteristic current and voltage patterns of a dangerous electrical arc and de-energizes the circuit. It is required for many dwelling-unit branch circuits to reduce the risk of fire from damaged or loose wiring.

An accidental low-resistance connection between two energized conductors or between an energized conductor and ground, allowing abnormally high current to flow. The resulting magnetic and thermal forces can damage equipment unless protection operates quickly.

The maximum current that a supply system can deliver into a short circuit at a given point. Equipment such as breakers and panelboards must have an interrupting or short-circuit current rating at least equal to this value.

The equipment at the supply end of a premises wiring system that contains the main disconnecting means, overcurrent protection, and metering provisions. It is the point where the utility supply connects to the building's electrical system.

The conductors that carry power from the utility service point to the service equipment of a building. Overhead and underground service drops, plus the service lateral, are sized according to calculated load and minimum code requirements.

All circuit conductors between the service equipment or source of a separately derived system and the final branch-circuit overcurrent devices. Feeders supply panelboards and subpanels and are sized from the load they carry.

The circuit conductors between the final overcurrent device protecting the circuit and the outlets or utilization equipment it serves. Branch circuits are classified by rating and by the types of loads they are permitted to supply.

A single panel or group of panel units containing buses and automatic overcurrent devices, arranged for installation in a cabinet. It distributes power to branch circuits or feeders and provides a place to terminate and identify them.

An enclosed channel designed expressly for holding wires, cables, or busbars, such as conduit, electrical metallic tubing, or wireway. Raceways provide mechanical protection and a path for conductors, and their fill is limited by code.

The percentage of a raceway's internal cross-sectional area occupied by conductors. Limits depend on the number of conductors, and exceeding them makes pulling difficult and traps heat that shortens insulation life.

The calculation of required cubic-inch volume for a box based on the number and size of conductors, devices, clamps, and grounding conductors entering it. An undersized box can damage insulation and cause overheating or arcing.

The reduction applied to a conductor's base ampacity when several current-carrying conductors share a raceway or cable, or when ambient temperature differs from the rating basis. Both factors are applied before comparing to the overcurrent device.

A multiplier applied to a conductor's ampacity when the surrounding air or earth is hotter than the temperature basis of the insulation rating. Hot locations such as attics and rooftops often require larger conductors.

A material, usually copper or aluminum, that carries electric current. Conductors are identified by size in American wire gauge or circular mils, by insulation type, and by the number of strands.

The nonconductive covering on a wire that confines current to its intended path and protects against shock and short circuits. Its material and thickness determine the maximum voltage and temperature the conductor can withstand.

An enclosure where conductors are spliced, connected to devices, or pulled through. It must be accessible, properly supported, closed with a cover, and sized by box-fill rules to contain all conductors and fittings safely.

A credential issued by the Delaware Board of Electrical Examiners that authorizes a person to perform electrical work in the state. Applicants must meet experience, examination, and fee requirements, and licenses require renewal.

The license level that allows a person to perform and supervise electrical work and to qualify a business for electrical contracting. It typically requires more documented experience and a passing score on the licensing examination.

A licensed electrician who performs electrical work under the direction of a master electrician or qualifying supervisor. The license requires documented field experience and a passing examination, and it is renewed periodically.

A business entity that contracts to perform electrical work and must hold a license and employ or be qualified by a licensed master electrician. The contractor is responsible for permits and code-compliant work.

A structured on-the-job training program combining paid field work with related classroom instruction under a licensed supervisor. Documented apprenticeship hours count toward the experience required for journeyperson and master license applications.

Required coursework that licensed electricians complete before renewing a license to keep current with code changes and safety practice. Hours, subject matter, and documentation rules are set by the state licensing board.

Written authorization from a local authority to install or alter electrical work, obtained before the job begins. The permit triggers required inspections and helps ensure the work meets the adopted code.

Review of electrical work by an authority having jurisdiction at stages such as rough-in, service, and final completion. Approval confirms code compliance and is needed before energizing equipment or occupying a building.

The organization, office, or individual responsible for enforcing code requirements and approving equipment, materials, and installations. Local inspectors and fire officials commonly serve in this role and may adopt stricter local amendments.

A document issued by a building official confirming that a structure complies with applicable codes and may be occupied. Final electrical inspection approval is usually required before one is issued for new or renovated buildings.

A widely adopted model code, published by the National Fire Protection Association, that sets minimum requirements for electrical installations. Delaware and its local jurisdictions enforce it, often with amendments and a specific edition in effect.

A safety procedure that isolates energy sources and applies locks and warning tags before work begins on equipment. Only the person who applied a lock removes it, preventing accidental energization and release of stored energy.

A dangerous release of energy caused by an electric arc through air, producing intense heat, light, pressure, and molten metal. Workers must use appropriate protective equipment and de-energize equipment when feasible.

Clothing and gear such as insulated gloves, eye protection, arc-rated clothing, and hard hats worn to reduce injury from shock, burns, and arc hazards. Selection depends on the task and the energy level present.

A worker who has demonstrated the skills and knowledge to safely construct, install, inspect, or maintain electrical equipment and who understands the hazards involved. Only qualified persons may work on or near exposed energized parts.

The required clear space in front of electrical equipment that allows safe operation and maintenance. Depth, width, and height depend on voltage and conditions, and the space must be kept free of storage.

The conductor of a circuit that is intentionally grounded at the source and returns current from line-to-neutral loads. It must never be bonded to ground again downstream of the service disconnect.

A delta-connected system with one winding center-tapped to provide a grounded neutral, giving two 120-volt legs and one leg at about 208 volts to neutral. The high leg must be identified and typically connects only to line-to-line loads.