three-wire system

(noun)

a modern wiring system with safety precautions; contains live, neutral, and ground wires

Related Terms

Examples of three-wire system in the following topics:

  • Safety Precautions in the Household

    • Modern household and industrial wiring requires the three-wire system, which has several safety features .
    • The three-wire system is connected to an appliance through a three-prong plug .
    • The three-wire system replaced the older two-wire system, which lacks an earth/ground wire .
    • The standard three-prong plug can only be inserted one way to ensure the proper function of the three-wire system.
    • The three-wire system connects the neutral wire to the earth at the voltage source and the user location.

  • Electric Currents and Magnetic Fields

    • For a long straight wire where I is the current, r is the shortest distance to the wire, and the constant 0=4π10−7 T⋅m/A is the permeability of free space.
    • (μ0 is one of the basic constants in nature, related to the speed of light. ) Since the wire is very long, the magnitude of the field depends only on distance from the wire r, not on position along the wire.
    • The curve C in turn bounds both a surface S through which the electric current passes through (again arbitrary but not closed—since no three-dimensional volume is enclosed by S), and encloses the current.
    • The force on a current carrying wire (as in ) is similar to that of a moving charge as expected since a charge carrying wire is a collection of moving charges.
    • (a) Compasses placed near a long straight current-carrying wire indicate that field lines form circular loops centered on the wire.

  • Getting over the hurdles

    • Yes, adding more insulation, installing rainwater collectors, fitting higher-quality windows, placing solar panels on roofs and putting passive shading structures over windows can incur extra expenses, but when these improvements eliminate the need for a heating and cooling system the extra costs can be negated.
    • Under-floor ventilation and wiring and super-efficient windows and daylighting are also incorporated.
    • Construction expenses remain virtually unchanged (mostly because of a reduction in heating, ventilation and air-conditioning needs) with subsequent energy costs reduced by one-half to three-fourths.

  • Length

    • For example: it is possible to cut a length of a wire which is shorter than wire thickness.
    • Length is a measure of one dimension, whereas area is a measure of two dimensions (length squared) and volume is a measure of three dimensions (length cubed).
    • In most systems of measurement, the unit of length is a fundamental unit, from which other units are defined.
    • Units of length may be based on lengths of human body parts, the distance traveled in a number of paces, the distance between landmarks or places on the Earth, or arbitrarily on the length of some fixed object.In the International System of Units (SI), the basic unit of length is the meter and is now defined in terms of the speed of light.
    • In U.S. customary units, English or Imperial system of units, commonly used units of length are the inch, the foot, the yard, and the mile.

  • Cylindrical and Spherical Coordinates

    • A cylindrical coordinate system is a three-dimensional coordinate system that specifies point positions by the distance from a chosen reference axis, the direction from the axis relative to a chosen reference direction, and the distance from a chosen reference plane perpendicular to the axis.
    • Cylindrical coordinates are useful in connection with objects and phenomena that have some rotational symmetry about the longitudinal axis, such as water flow in a straight pipe with a round cross-section, heat distribution in a metal cylinder, electromagnetic fields produced by an electric current in a long, straight wire, and so on.
    • Then the $z$ coordinate is the same in both systems, and the correspondence between cylindrical $(\rho,\varphi)$ and Cartesian $(x,y)$ are the same as for polar coordinates, namely $x = \rho \cos \varphi; \, y = \rho \sin \varphi$.
    • A spherical coordinate system is a coordinate system for three-dimensional space where the position of a point is specified by three numbers: the radial distance of that point from a fixed origin, its polar angle measured from a fixed zenith direction, and the azimuth angle of its orthogonal projection on a reference plane that passes through the origin and is orthogonal to the zenith, measured from a fixed reference direction on that plane.
    • A cylindrical coordinate system with origin $O$, polar axis $A$, and longitudinal axis $L$.

  • Other Neurological Disorders

    • Epilepsy and stroke are examples of neurological disorders that arise from malfunctions in the nervous system.
    • These include chronic pain conditions, cancers of the nervous system, epilepsy disorders, and stroke.
    • Estimates suggest that up to three percent of people in the United States will be diagnosed with epilepsy in their lifetime.
    • For example, people who have intellectual disability or autism spectrum disorder can experience seizures, presumably because the developmental wiring malfunctions that caused their disorders also put them at risk for epilepsy.

  • Orthodontics

    • For comprehensive orthodontic treatment, metal wires may be inserted into orthodontic brackets (dental braces), which can be made from stainless steel or a more aesthetic ceramic material .
    • The wires interact with the brackets to move teeth into the desired positions.
    • Many countries have their own systems for training and registering orthodontic specialists.
    • A two-to-three-year period of full-time post-graduate study is required for a dentist to qualify as an orthodontist.

  • Combination Circuits

    • This is commonly encountered, especially when wire resistances is considered.
    • In that case, wire resistance is in series with other resistances that are in parallel.
    • In the figure, the total resistance can be calculated by relating the three resistors to each other as in series or in parallel.
    • Essentially, wire resistance is a series with the resistor.
    • If a large current is drawn, the IR drop in the wires can also be significant.

  • Artificial Pacemakers

    • The primary purpose of a pacemaker is to maintain an adequate heart rate, either because of the heart's native pacemaker is not fast enough, or there is a block in the heart's electrical conduction system.
    • A pacemaker is composed to two parts, the pacing electrodes, or leads, which are wires that are inserted directly into the heart, and a pacemaker generator.
    • There are three basic types of permanent pacemakers, classified according to the number of chambers involved and their basic operating mechanism:
    • Here, wires are placed in two chambers of the heart.
    • This chest x-ray shows an installed artificial pacemaker with wire routing used to contact the heart to regulate beating.

  • Vision: The Visual System, the Eye, and Color Vision

    • The human visual system gives our bodies the ability to see our physical environment.
    • The system requires communication between its major sensory organ (the eye) and the core of the central nervous system (the brain) to interpret external stimuli (light waves) as  images.
    • The eye has three major layers:
    • The optic chiasm is a complicated crossover of optic nerve fibers behind the eyes at the bottom of the brain, allowing the right eye to "wire" to the left neural hemisphere and the left eye to "wire" to the right hemisphere.
    • Depth perception refers to our ability to see the world in three dimensions.