PROPERTY & BUILDING INSPECTION MODULE 2 Flashcards
Electrical System
Ampacity
the maximum current that a conductor or device may carry continuously without exceeding its temperature rating.
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.
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
conductors that begin at a circuit breaker or fuse and serve one or more outlets.
Branch circuit, multi-wire
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 multi-wire branch circuits.
Bus
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
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).
Conductor
a material, such as copper or aluminum, that permits electricity to flow with low resistance; wires are conductors.
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); expressed as I in Ohm’s Law and Watt’s Law equations
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.
Enclosure (electrical)
a case or cabinet intended to prevent accidental contact with energized parts; a panelboard is housed inside an enclosure.
Feeder conductors
conductors from the service equipment or from a panelboard that supply electricity to another panelboard such as a subpanel.
Grounded
a conductor that is intentionally connected to the earth; this describes what is often called the neutral conductor.
Grounding
providing an intentional connection to the earth; grounding provides 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. See Grounding electrode and Grounding electrode conductor (GEC).
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
metal that is in direct contact with the earth and serves as the electrical system grounding connection; examples include copper-coated steel rods, galvanized steel pipes, water service and well pipes, and reinforcing steel encased in the footings.
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.
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.
Knockouts
stamped openings in an enclosure where conduit or cable clamps are installed to secure conductors or cables. See Tabs (twistouts)
Ohm’s Law and Watt’s Law
expressions of the relationship between current, volt-age, power, and resistance; expressed as Power = Volts X Amps and Resistance = Volts/ Amps.
Joules Law
a formula for calculating heat in an electrical circuit expressed as Heat = Current2 X Resistance X Time
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.
Ground fault circuit interrupter (GFCI)
a circuit breaker or receptacle that detects a ground fault by monitoring the imbalance in current flow between the energized and neutral conductors and stops current flow (opens the circuit) when a ground fault is detected.
