Electrical system terms

Typical Defects. Switches:

(8) 3-way and 4-way switches do not function properly in all switch positions, (9) dimmer switches do not function properly, (10) switch is installed where not allowed, e.g. above bathtub, (11) switch operates intermittently, (12) switch is unusually warm, (13) switch appears to control a load greater than its ampacity rating, (14) switch is installed upside down, (15) switch is located behind a door or in another inconvenient location.

Typical Defects. Receptacles

(8) receptacle is improperly wired, e.g., reverse polarity, not grounded, open neutral, (9) receptacle has no power, (10) receptacle ampacity rating not compatible with branch circuit, (11) receptacle is not installed where required, e.g., kitchen countertop receptacles too far apart, (12) receptacle is installed where not allowed, e.g. above bathtub, (13) receptacles are not AFCI or GFCI protected where required.

Armored cabel - AC

AC is a factory-made assembly of insulated conductors in a flexible interlocking metallic covering. Common sizes used in house wiring are around 1/2 inch diameter.AC is limited to interior dry locations, such as in walls and in masonry cells that are not exposed to dampness or below grade

AWG:

AWG: the abbreviation for American Wire Gauge, a system for identifying the diameter of electrical wires; larger numbers identify smaller diameter wires; #14 (pronounced number 14 or 14 gauge) is the smallest wire used in house wiring and 4/0 (pronounced four-oh) is usually the largest.

Absent or improper handle ties on 240 volt or multiwire branch circuit breakers

Absent or improper handle ties on 240 volt or multiwire branch circuit breakers: both conductors of these circuits must shut off together; only approved handle ties may be used; wires, nails, and other improvised handle ties are not permitted.

Absent tabs and knockouts

Absent tabs and knockouts: this is an electrical shock hazard; tabs and knockouts must be replaced with material similar to the original; tape, cardboard, and similar improvised materials are not permitted.

Ampacity:

Ampacity: the maximum current that a conductor or device may carry continuously without exceeding its temperature rating.

Bonding

Bonding: the process of connecting, both physically and electrically, metal components of the electrical system that are not intended to carry electrical current to provide a low resistance return path to the circuit breaker or fuse to clear ground faults; bonding is an electrical safety system.

Bonding:

Bonding: the process of connecting, both physically and electrically, metal components of the electrical system that are not intended to carry electrical current to provide a low resistance return path to the circuit breaker or fuse to clear ground faults; bonding is an electrical safety system.

Branch circuit, multiwire

Branch circuit, multiwire: a branch circuit in which two energized conductors share one neutral conductor; examples can include clothes dryers, ranges and other cooking appliances, and split-wire receptacle circuits; 240 volt water heaters and condensers for air conditioners and heat pumps are not usually multiwire branch circuits.

Branch circuit

Branch circuit: conductors that begin at a circuit breaker or fuse and serve one or more outlets

Branch circuits not labeled

Branch circuits not labeled: branch circuits should be labeled with a permanent marking in sufficient detail to distinguish the branch circuit from other branch circuits; identification by a reference to occupant specific room uses is not acceptable.

Bus (buss, busbar):

Bus (buss, busbar): the heavy, rigid metal part of a panelboard on which circuit breakers or fuses are mounted; sometimes used to describe metal terminals to which the neutral and equipment grounding conductors (EGCs) are connected.

Cable

Cable: two or more conductors encased in sheathing; examples include non-metallic sheathed cable (often referred to by the brand name Romex) and armored cable (often referred to by the brand name BX).

Cables and conduit not secured to enclosure:

Cables and conduit not secured to enclosure: each cable should enter an enclosure through a cable clamp or within conduit; metal conduit should be connected to the enclosure with a metal fitting or should have a bonding jumper.

Circuit breaker manufacturer different from panelboard manufacturer

Circuit breaker manufacturer different from panelboard manufacturer: panelboards and circuit breakers are made to work as a system; a device from a different manufacturer may not be used even if it seems to fit.

Circuit breaker:

Circuit breaker: see Overcurrent protection device (OPD).

Conductor:

Conductor: a material, such as copper or aluminum, that permits electricity to flow with low resistance; wires are conductors.

Conductors not inserted straight into terminals

Conductors not inserted straight into terminals: conductors should be installed so that the conductor is substantially straight as it enters a terminal; conductors that are substantially skewed may not be securely fastened in the terminal.

Contaminants such as paint and dry wall joint compound in the enclosure:

Contaminants such as paint and dry wall joint compound in the enclosure: this could increase resistance and cause an electrical fire.

Current

Current: the amount of electricity in a circuit; (similar to water gallons per minute; water flow in a pipe); unit of measure is the Ampere (Amp).

Damaged conductors and insulation:

Damaged conductors and insulation: conductors and insulation should be intact; nicked conductors and insulation and multi-strand conductors with absent strands should be cut back to intact material or should be replaced.

Damaged enclosure:

Damaged enclosure: enclosures should be intact with all manufacturer approved parts and be free from physical damage; covers and doors should operate smoothly and open at least 90° to allow safe access to interior components.

Dead front cover

Dead front cover: a panel that is removed to gain access to the energized components inside an enclosure; the dead front cover is usually behind a door that must be swung or lifted to gain access to the dead front cover.

EGC:

EGC: see Grounding conductor, equipment (EGC).

Electrical Metallic Tubing (EMT):

EMT, sometimes called thin wall, is a round pipe designed for routing and protection of conductors and cables. made from steel, aluminum common sizes 1/2 to 4 inches comes in 10 foot sections most locations buried, embedded in concrete supported every 10 feet and 3 feet from boxes and terminations

Electrical Nonmetallic Tubing (ENT):

ENT is a flexible corrugated tube designed for routing and protection of conductors and cables. It is usually made from PVC. common sizes 1/2 to 2 inches supported every 3 feet and 3 feet from boxes and termination

Enclosure (electrical):

Enclosure (electrical): a case or cabinet intended to prevent accidental contact with energized parts; a panelboard is housed inside an enclosure.

Energized neutral conductors not marked as energized

Energized neutral conductors not marked as energized: neutral conductors may be used as energized conductors but they must be permanently marked in the enclosure and at all accessible points; this is usually done with electrical tape or a black marker.

Excess uninsulated conductor at circuit breaker lug:

Excess uninsulated conductor at circuit breaker lug: no uninsulated conductor should extend past the circuit breaker case; this is a possible electric shock hazard.

flexible metal conduit

FMC is a flexible tube made of helically wound interlocking metal designed for routing and protection of conductors and cables. made from steel, aluminum including galvanized, stainless steel common sizes 1/2 to 4 inches

Feeder conductors

Feeder conductors: conductors from the service equipment or from a panelboard that supply electricity to another panelboard such as a subpanel.

Fuse:

Fuse: see Overcurrent protection device (OPD).

Fused neutral:

Fused neutral: neutral conductors should not be connected to OPDs because in the unlikely event that the OPD opens the neutral conductor, current flow will stop but the circuit will remain energized; this is usually an issue for very old electrical systems.

Ground fault:

Ground fault: an event that occurs when metal that should not conduct electricity (such as a metal water pipe) becomes energized; if the metal is properly bonded, current flow should increase in the circuit and trip the circuit breaker or fuse.

Grounded:

Grounded: a conductor that is intentionally connected to the earth; this describes what is often called the neutral conductor.

Grounding conductor, equipment (EGC):

Grounding conductor, equipment (EGC): a bare or green insulated conductor that provides a ground fault current path (a bonding connection) for equipment with metal cases and parts; these have been installed in most house branch circuit wiring since around 1960.

Grounding electrode conductor (GEC):

Grounding electrode conductor (GEC): a conductor that runs between the grounding electrode and an accessible point downstream from where the grounded service entrance conductor connects to the service drop or lateral; the GEC connection is usually at the service equipment.

Grounding electrode:

Grounding electrode: metal that is in direct contact with the earth and serves as the electrical system grounding connection; examples include copper rods, galvanized steel pipes, water service and well pipes, and reinforcing steel encased in the footings.

Grounding:

Grounding: providing an alternate path for current to return to its source; in an electrical power system, the source is the utility's transformer and ultimately the power plant, ee Grounding electrode and Grounding electrode conductor (GEC).

Knockouts

Knockouts: stamped openings in an enclosure where conduit or cable clamps are installed to secure conductors or cables. See Tabs (twistouts).

Load center

Load center: see Panel (panelboard, load center).

Low voltage components inside enclosure and conduit

Low voltage components inside enclosure and conduit: components such as door bell transformers and telephone and coaxial cable may not be inside enclosures, and conduit containing high voltage components unless the low and high voltage components are physically separated by non-conductive guards.

Lug

Lug: a connection point where conductors are inserted and secured; examples include the connection points on panelboards for service entrance and feeder conductors, on terminal bars for neutral and EGCs, and on circuit breakers for branch circuit conductors.

Metale-clad cable

MC

Melted insulation and charred conductors:

Melted insulation and charred conductors: this indicates a loose connection at the lug or overcurrent that was not interrupted by the OPD.

Ohm's law and Watt's law

Ohm's law and Watt's law: expressions of the relationship between current, voltage, power, and resistance; expressed as Power = Volts X Amps and Resistance = Volts/Amps.

Outlet:

Outlet: a place where current is taken for use; examples include receptacles, light fixtures, and connections at electric appliances such as water heaters.

Overcurrent protection device (OPD):

Overcurrent protection device (OPD): a fuse or a circuit breaker; overcurrent protection devices interrupt the flow of electricity when a set current flow is exceeded (an overload), or when a short circuit fault is detected; these devices prevent conductors and devices from overheating and causing fires.

Panel (panelboard, load center):

Panel (panelboard, load center): the equipment on which circuit breakers or fuses are mounted; panels include associated terminal bars; a panelboard is contained in an enclosure; the first and usually the largest panel is often referred to as the main panel or the service panel; however, there are no generally accepted terms to identify panels.

Panelboard ampacity less than service entrance or feeder conductor ampacity:

Panelboard ampacity less than service entrance or feeder conductor ampacity: the panelboard label states the maximum ampacity of the supply conductors that should serve the panelboard; the conductors may be less than the maximum capacity, but not greater.

Power:

Power: a measure of the work performed by electricity; unit of measure is the Watt.

Raceway:

Raceway: enclosed metallic or nonmetallic components designed and listed for holding conductors or cables between points in the electricity distribution system of the house; examples include various types of conduit and tubing.

Receptacle:

Receptacle: an outlet designed to accept a plug that supplies electricity to an appliance.

Resistance:

Resistance: the property of a material to allow or restrict the flow of electricity; materials with low resistance are conductors and materials with high resistance are insulators; unit of measure is the Ohm.

Rust

Rust: this is an indication of a possible water leak into the enclosure; this could increase resistance and cause an electrical fire.

Screws with points used to secure enclosure covers:

Screws with points used to secure enclosure covers: points could penetrate conductor insulation and energize the enclosure.

Service drop and service lateral

Service drop and service lateral: the conductors between the transformer belonging to the utility and the house; a service drop is above-ground and a service lateral is below ground

Service entrance conductors

Service entrance conductors: the conductors between the service drop or service lateral and the service equipment

Service equipment:

Service equipment: the circuit breakers, switches, or fuses that shut off power to the house; all power should be shut off using six or fewer circuit breakers, switches, or fuses; often called the main shutoff or main disconnect.

Service point:

Service point: the place where the service drop or service lateral conductors end and the house service entrance conductors begin; this is usually at the drip loops for service drops; the service point for service laterals is more difficult to distinguish, but is often at the meter.

Short circuit

Short circuit: this event occurs when current flows between conductors in an unintended manner, such as between the hot and neutral conductors.

Single phase electrical service:

Single phase electrical service: electrical service consisting of two energized 120 volt conductors and one grounded conductor; this is by far the most common residential electrical service.

Subpanel:

Subpanel: a panelboard that receives power from an upstream panelboard, usually the main panelboard; also called a downstream or a distribution panel; however, there are no generally accepted terms to identify panels.

Tabs (twistouts):

Tabs (twistouts): rectangular metal pieces on the dead front cover that are removed before installing a circuit breaker; tabs must be replaced by a filler plate if a tab has been removed and no circuit breakers is installed. See Knockouts.

Terminal bars:

Terminal bars: metal bars associated with a panelboard on which neutral and equipment grounding conductors (EGCs) are mounted; called a neutral bar when neutral conductors or neutral and EGCs are connected; called a ground bar if only EGCs are connected.

Three phase electrical service:

Three phase electrical service: electrical service consisting of three energized conductors and one grounded conductor; this service type is mostly for commercial and industrial buildings.

Too many circuit breakers on panelboard/half- height circuit breakers in wrong slots:

Too many circuit breakers on panelboard/half- height circuit breakers in wrong slots: the panelboard label states how many branch circuits the panel may serve and which, if any, slots may contain half-height circuit breakers

Typical Defects. Receptacles

Typical Defects. Receptacles: (1) receptacle is loose, (2) receptacle is damaged, scorched, aged, or painted, (3) cover plate is absent, damaged, or loose, (4) gap exists between receptacle and cover plate or between cover plate and wall, (5) damp or wet area cover is not installed where required or the cover is damaged, (6) receptacle is connected to an improper branch circuit, e.g. receptacle not in a bathroom is on the bathroom branch circuit, (7) box is inadequately supported,

Typical Defects. Switches:

Typical Defects. Switches: (1) switch is loose, (2) switch is damaged, scorched, aged, or painted, (3) cover plate is absent, damaged, or loose, (4) gap exists between switch and cover plate or between cover plate and wall, (5) damp or wet area cover is not installed where required or cover is damaged, (6) switch box is inadequately supported, (7) switch has no power,

Voltage:

Voltage: the pressure of electricity in a circuit, similar to water pressure in a pipe; unit of measure is the Volt.

Wiring methods

Wiring methods: cables and raceways approved for distributing electricity from the service point to panelboards and outlets; examples include armored cable, nonmetallic sheathed cable, and various types of conduit and tubing.