Residential Electrical Lesson 2 – electrical systems fundamentals, wiring methods, and safety
concepts
American Wire Gauge (AWG) - ✔✔a scale of specified diameters and cross sections for wire
sizing that is the standard wire-sizing scale in the United States
ampacity - ✔✔The current, in amperes, that a conductor can carry continuously under the
conditions of use without exceeding its temperature rating.
antioxidant - ✔✔A special compound that is applied to exposed aluminum conductors; its
purpose is to inhibit oxidation
approved - ✔✔when a piece of electrical equipment is approved, it means that it is acceptable
to the authority having jurisdiction (AHJ)
bimetallic strip - ✔✔a part of a circuit breaker that is made from two different metals with
unequal thermal expansion rates; as the strip heats up, it will tend to bend
cabinet - ✔✔an enclosure for a panelboard that is designed for either flush or surface
mounting; a swinging door is provided
cable - ✔✔a factory assembly of two or more insulated conductors that have an outer
sheathing that holds everything together; the outside sheathing can be metallic or nonmetallic
circuit breaker - ✔✔a device designed to open and close a circuit manually and to open the
circuit automatically on a predetermined overcurrent without damage to itself when properly
applied within its rating
circular mils - ✔✔the diameter of a conductor in mils (thousandths of inches) squared; the
number of circular mils is the cross-sectional area of a conductor
, connector - ✔✔a fitting that is designed to secure a cable or length of conduit to an electrical
box
copper-clad aluminum - ✔✔an aluminum conductor with an outer coating of copper that is
bonded to the aluminum core
device - ✔✔a piece of electrical equipment that is intended to carry but not use electrical
energy; examples include switches, lamp holders, and receptacles
device box - ✔✔an electrical device that is designed to hold devices such as switches and
receptacles
disconnecting means - ✔✔a switch that is able to de-energize an electrical circuit or piece of
electrical equipment; sometimes referred to as the "disconnect"
fitting - ✔✔an electrical accessory, such as a locknut, that is used to perform a mechanical
rather than an electrical function
fuse - ✔✔an overcurrent protection device that opens a circuit when the fusible link is melted
away by the extreme heat caused by an overcurrent
ganging - ✔✔joining two or more device boxes together for the purpose of holding more than
one device
ground fault - ✔✔an unintended low-resistance path in an electrical circuit through which
some current flows to ground using a pathway other than the intended pathway; it results when
an ungrounded "hot" conductor unintentionally touches a grounded surface or grounded
conductor
concepts
American Wire Gauge (AWG) - ✔✔a scale of specified diameters and cross sections for wire
sizing that is the standard wire-sizing scale in the United States
ampacity - ✔✔The current, in amperes, that a conductor can carry continuously under the
conditions of use without exceeding its temperature rating.
antioxidant - ✔✔A special compound that is applied to exposed aluminum conductors; its
purpose is to inhibit oxidation
approved - ✔✔when a piece of electrical equipment is approved, it means that it is acceptable
to the authority having jurisdiction (AHJ)
bimetallic strip - ✔✔a part of a circuit breaker that is made from two different metals with
unequal thermal expansion rates; as the strip heats up, it will tend to bend
cabinet - ✔✔an enclosure for a panelboard that is designed for either flush or surface
mounting; a swinging door is provided
cable - ✔✔a factory assembly of two or more insulated conductors that have an outer
sheathing that holds everything together; the outside sheathing can be metallic or nonmetallic
circuit breaker - ✔✔a device designed to open and close a circuit manually and to open the
circuit automatically on a predetermined overcurrent without damage to itself when properly
applied within its rating
circular mils - ✔✔the diameter of a conductor in mils (thousandths of inches) squared; the
number of circular mils is the cross-sectional area of a conductor
, connector - ✔✔a fitting that is designed to secure a cable or length of conduit to an electrical
box
copper-clad aluminum - ✔✔an aluminum conductor with an outer coating of copper that is
bonded to the aluminum core
device - ✔✔a piece of electrical equipment that is intended to carry but not use electrical
energy; examples include switches, lamp holders, and receptacles
device box - ✔✔an electrical device that is designed to hold devices such as switches and
receptacles
disconnecting means - ✔✔a switch that is able to de-energize an electrical circuit or piece of
electrical equipment; sometimes referred to as the "disconnect"
fitting - ✔✔an electrical accessory, such as a locknut, that is used to perform a mechanical
rather than an electrical function
fuse - ✔✔an overcurrent protection device that opens a circuit when the fusible link is melted
away by the extreme heat caused by an overcurrent
ganging - ✔✔joining two or more device boxes together for the purpose of holding more than
one device
ground fault - ✔✔an unintended low-resistance path in an electrical circuit through which
some current flows to ground using a pathway other than the intended pathway; it results when
an ungrounded "hot" conductor unintentionally touches a grounded surface or grounded
conductor
