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Basic Electricity

Electrical Voltages

Low Voltage

Electrical Definitions

Ohm’s Law

Electrical Circuits

Multi-wire Branch Circuits

Circuit Current Ratings

NM Cable (Romex®)

Wire Connectors (Wire-nuts)

Basic Electricity

Insulator atomConductor Atom

Conductor Atom

Insulator atom

Single electron in outer orbit

120 V Sine Wave Diagram

Current flows in both directions. 120 VAC household power is an example of AC current. The current in 120 VAC changes direction 120 times per second as shown below.

Direct and Alternating Current

At 0 degrees the voltage is at 0 volts and starts to rise to a peak voltage of 170 volts at 90 degrees. At 90 degrees the voltage goes back down to 0 volts at 180 degrees. The current then reverses direction and rises to a peak voltage of -170 volts at 270 degrees. To complete the cycle the current goes back to 0 volts at 360 degrees and the cycle starts over.

For detailed information about electrical circuits see All About Circuits

 Conductor and Insulator Properties

An electrical current (the movement of electrons) happens when there is a potential difference (voltage) between the ends of a conductor.

Multiple electrons in outer orbit

Direct current (DC) Diagram Alternating current (AC)  Diagram 120 V Sine Wave

Current flows in one direction. A battery operated flashlight is a very common example of direct current.

Alternating current (AC)

Direct current (DC)