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Fundamentals of Electricity

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What is Current

Current is a measure of the rate of electron flow through a material. Electrical current is measured in units of amperes or "amps" for short. This flow of electrical current develops when electrons are forced from one atom to another.

Electron Flow Graphic

One amp is defined as 6.28 x 10 18 electrons per second.

When current flows in a conductor, heat is produced. This happens because every conductor offers some resistance to current flowing.

That is why the amperage flow in a circuit is important, since the more amps flowing, the more heat is produced. Most people notice this heating effect when the cord of any appliance or electrical device heats up after the device has been running for an extended period.

Recognizing this heat production is important in specifying wire sizes. When a wire carries more amps than it can handle without overheating, we say it is "overloaded". Overloaded wires can melt the insulation and create shocks or even fires.

Wire Sizes Graphic

The scientific symbol for amperage is an "I", dating back to the early days of electricity. It is still used by scientists and engineers. Electricians and wiring guides use "A" as the amperage symbol. In this title, we'll use the practical symbol "A" for current flow in amps.