In a cable, burried in the Earth, or in open air. This is typically in a raceway (cable-tray or conduit), Installation - Choose the installation method for the circuit. Common conductors are copper and aluminum. Insulation - Select the thermal rating of the insulation on the wire.Ĭonductor - Choose the material used as a conductor in the wire. To calculate ground wire size, use the Ground Wire Size Calculator. For three-phase circuits, four wires are required. Single-phase circuits, three wires are required. This is typically single-phase or three-phase. Phases - Select the number of phases in the circuit. To multiply the nameplate FLA by 1.25 for wire sizing. While three-phase voltages are typically 208V, 230V or 480V.Īmperes - Enter the maximum current in amps that will flow through the circuit. Single-phase voltages are usually 115V or 120V, There are many devices that measure units in terms of milliamperes such as galvanometers and ammeters, though these devices do not exclusively measure milliamperes.Voltage - Enter the voltage at the source of the circuit. The ampere can be preceded by any of the metric prefixes in order to report units in the desired magnitude.Ĭurrent use: As a submultiple of an SI unit, the milliampere is used worldwide, often for smaller measurements of electrical current.
The prefix "milli" indicates one thousandth of the base unit it precedes, in this case the ampere. History/origin: The milliampere has its origins in the ampere. It is defined as one thousandth of an ampere. Milliampereĭefinition: A milliampere (symbol: mA) is a submultiple of the SI base unit of electrical current, the ampere. An ampere can be expressed in the form of watts/volts, or W/V, such that an ampere equals 1 W/V, since power is defined as a product of current and voltage.
#Amp to volt conversion calculator free#
One potential drawback of the redefinition is that vacuum permeability, vacuum permittivity, and impedance of free space were exact before the redefinition, but will now be subject to experimental error.Ĭurrent use: As the SI base unit of electric current, the ampere is used worldwide for almost all applications involving electric current.
Now, it is only dependent on the definition of the second. Previously, since the definition included a reference to force, the SI kg, meter, and second needed to be defined before the ampere could be defined. This definition was difficult to realize with high precision, and as such was changed to be more intuitive, and easier to realize. In terms of the SI unit of charge, the coulomb, one ampere is defined as one coulomb of charge passing through a given point in one second. Before 2019, the ampere was defined formally as the constant current at which a force of 2 × 10 -7 newtons per meter length would be produced between two conductors, where the conductors are parallel, have infinite length, are placed in a vacuum, and have negligible circular cross-sections. The size of the unit was chosen such that it would fit conveniently within the metre-kilogram-second system of units. In the centimeter-gram-second system of units, the ampere was defined as one tenth of the unit of electrical current of the time, which is now known as the abampere. History/origin: The ampere is named after Andre-Marie Ampere, a French mathematician and physicist.
This definition is effective since 2019, and is a significant change from the previous definition of the ampere. The second is defined based on the cesium frequency, Δ νCs. The ampere is defined formally based on a fixed value for the elementary charge, e, of 1.602176634 × 10 -19 when expressed in the unit C, which is equal to A Definition: The ampere (symbol: A), often referred to as simply amp, is the base unit of electric current in the International System of Units (SI).
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