Electrical Basics

Wiring a house or a basement in a house is something many do-it-yourselfers can tackle.  It does require some basic electrical understanding and knowledge of electrical codes but if you have a little of this background you can make it happen.  This website is indented to give some guidance for your wiring projects starting with some basic electrical theory as well as an overview of the types of electrical cable you'll be using when wiring a house.


Voltage or Volts(V)

The voltage between two points is a short name for the electrical force that would drive an electric current (measured in Amps) between those points. For beginners, an analogy easier to understand, would be "pressure" in a water pipe.  The higher the pressure, the more water you can deliver through a given size pipe.  Likewise, a #12 copper wire at 240V and 10Amps can deliver twice the energy or Watts than that same conductor at 120V and 10Amps.

Amperage or Amps(A)

Amps are a measure of the flow of "electrical current".  This is analogous to the flow of water in a pipe.  Amps are very important when it comes to sizing the wires or conductors in your project.  Conductors are generally rated in terms of amperage.  Running too many amps through a wire will cause the wire to overheat can cause a fire.  This is why circuit breakers are also rated in terms of Amps.  If you look in your home electrical panel you will see a bunch of 15A and 20A circuit breakers (unless you have a really old home with fuses).  Circuit breakers are matched to the size of conductors tied to them and are designed to trip to protect those wires.

Resistance (R)

Electrical resistance measures opposition to the passage of electric current.  Resistance in measured in ohms.   If thinking about the flow of electricity like the flow of water in a pipe, the resistance is similar to resistance in a water pipe.  The smaller the diameter of the pipe, the more resistance you have, and in turn the less water you can deliver with a given amount of pressure. Likewise, the smaller the diameter of copper wire you use, the less energy you can safely carry down the wire.


Watts are a measurement of electrical energy.  Watts are directly related to Volts and Amps (Watts = Volts x Amps).  Utility companies bill you for the number of kwh (kilowatt hours or 1000 Watts for an hr) used each month.

Ohm's Law

Ohm's law states that the current through a conductor between two points is directly proportional to the potential difference (voltag) across the two points, and inversely proportional to the resistance between them. The mathematical equation that describes this relationship is as follows:


where I is the current through the conductor in amps, V is the potential difference measured across the conductor in volts, and R is the resistance of the conductor in units of ohms.

Voltage-Current-Resistance-Power Calculator

Enter any two of the following values and press calculate button.

Voltage (Volts):
Current (Amps):
Resistance (Ohms):
Power (Watts):


Common Electrical Wiring Diagrams

Frequently Asked Electrical Questions

Wire Gauge and Voltage Drop Calculator

NEC Reference Tables (2011, 2008, 2005, 2002, and 1999)

Electrical - The Basics

Residential Electrical Guidelines and Codes

Rough-In Electrical and Pulling Cable

Breakers and Fuses

Wire Types and Sizing

Sizing Your Electrical Service

Electrical - Main Service Line Installation

Fire/Smoke Alarm Installation

Doorbell Wiring

Phone Wiring

Low-Voltage Wiring

Cable Pinouts

Click the icons below to get our NEC® compliant Electrical Calc Elite or Electric Toolkit for Android and iOS.  The Electrical Calc Elite is designed to solve many of your common code-based electrical calculations like wire sizes, voltage drop, conduit sizing, etc.  The Electric Toolkit provides some basic electrical calculations, wiring diagrams (similar to those found on this website), and other electrical reference data. 

 electric-toolkit-android     Electrical Calc Elite