# ELECTRICAL BASICS

### Whether you’re starting out or a veteran contractor, understanding basic definitions and materials is the first step to working successfully with your trade partners.

## Definitions

**Alternating Current** (AC), standard house current, is delivered to homes by the local electric utility. It reverses direction 60 times per second in a residential circuit.

**Amperage** describes current flow. It’s the number of electrons per second passing a given point on the wire. To calculate the number of amps flowing through a circuit, divide the total watts by the voltage: a = w 4 v

**Circuits** are unbroken paths along which an electrical current flows. Each circuit forms a closed loop from the power source to the load and back.

**Conductors** are metal wires, usually aluminum or copper, that conduct the electricity from its source to its load.

**Derated Load** is the computed load of a given electrical circuit or group of circuits after it has been adjusted per the formulas given in the National Electric Code (NEC.)

**Direct Current** (DC) flows in one direction. Batteries supply direct current.

**Electricity** is the flow of electrons that takes place when a charge is created, raising the voltage potential of one point over another.

**Ground** is the conducting connection between an electrical circuit or an electrical device and the earth.

**Loads** are any appliances that use electricity, from a night-light to a central air conditioner.

**Ohm’s Law **is the relationship between voltage, amperage, and resistance: Voltage = Amperage x Resistance.

**Resistance** is a measure of how well a material conducts electricity. It’s measured in ohms. Conductors have low resistance, insulators have high resistance.

**Voltage **is a measure of electrical pressure or force. The greater a circuit’s voltage, the more current it will deliver to a given load. Most homes have a 240-volt service. Actual voltage fluctuates from 220 to 240 (or 110 to 120 volts).

**Wattage **is power consumption: the product of voltage and amperage. It’s used to estimate circuit capacity.

**Watt-hours** is a measure of power consumption over time. One watt-hour equals one watt of electricity used for one hour.

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