101 (Basic Electrical Terms and Common Voltages!)

Voltage

Similar to pressure and relates to how hard electricity is being “pushed” through a conductor. It is more related to the amount of pressure (push, force).

• Voltages you typically work on are 120, 208, 240, 277, and 480.

Nominal single-phase voltage

It is common in residential areas ranging at 120/240 volts. Actual voltages can vary from 5 to 10%.

Nominal three-phase voltage

It is common in commercial (at 120/208 volts) and industrial (at 277/480 volts) areas. Actual voltages can vary from 5 to 10%.

Rated Voltage

It is the voltage the manufacturer has chosen for a specific piece of equipment or device.

• Example: light bulb rated 100 watts at 130 volts needs to be connected to a 130-volt circuit instead of 120-volt circuit since the actual output watts will be smaller.

Ampacity

Also referred to as amperes or current, is the amount of electricity that flows through a conductor (wire) without exceeding its temperature rating. As ampacity increases, conductor size increases. It is similarly related to the amount of water or electricity.

Wattage (Watts)

Refers to the amount of work being accomplished. It solely DEPENDS on the force of the water (voltage) and the amount of water (ampacity) to have the wheel spin.

• THIS IS POWER!!!

Resistance

It is the opposition to ampacity (current). For example, rocks and other debris build up affect the water’s flow. It is basically another word for “protection.” The unit of measure is (ohms). The higher ohms. the higher the resistance.

Circuit Breakers

Found in the Panel, Panelload, Load Center, and Switchgear. They are switches that allow a certain amount of electricity (amperes/ampacity) to flow through. If the ampacity is more than the rating of the switch/fuse, it will trip or blow and turn off the circuit, protecting the wire from having too much current flow through it.

Grounded Conductor

Completes the loop and returns to the panel. It is usually white or gray.

Ungrounded Conductor

Runs from the panel to the appliance, light, or similar.

Grounding Conductor/Ground

The grounding conductor is installed for safety. Metal boxes, metal conduits, and other metallic components should NOT carry current. The ground causes a breaker or fuse to turn the circuit off so a dangerous condition does NOT exist. This will be in color green or bare.

Conduits

They provide a way for current (from the panel) to travel to the receptacle, light, appliance, and similar.

• They are raceways requiring wire (conductors) to be pulled through them.

Cables

They provide a way for current (from the panel) to travel to the receptacle, light, appliance, and similar.

• They come with conductors preinstalled.

Rigid Metallic Conduit (RMC)

Heavy gauge conduit that typically have threaded connections. It is mainly used in manufacturing facilities since it is one of the tougher conduits.

Electrical Metallic Tubing (EMT)

A lighter gauge conduit that is NOT threaded. It’s probably the most common type of conduit installed, Most likely used in commercial facilities like offices or schools. It is cheaper and takes less time to install than RMC.

Flexible Metallic Conduit (FMC)

A flexible metallic conduit that are typically used in short sections at the tail end of a conduit run where the conduit may need to be flexible, such as on a motor.

Polyvinyl Chloride (PVC)

With underground work, many times it will be used. It’s a plastic conduit that is inexpensive and installs quickly.

Metallic and Nonmetallic Liquid-Tight Conduit (LFMC and LFNC)

This type of conduit is like flex except it has an outer covering that is weatherproof. It’s often seen used outside to connect to an air conditioning unit.

THHN/THWN

Most common type of conductor used in wet locations or in high-temperature areas. They are classified by their insulation type.

Nonmetallic Sheathed Cable (NM Cable)

This cable is plastic and is seen in many residential settings. On a jobsite, it may be used to run temporary power and lighting. It is NOT often allowed in commercial or industrial jobs.

Metal-Clad Cable (MC Cable)

This flexible cable has metallic jacket instead of a plastic one. Oftentimes, they are seen in walls to supply power to receptacles and light fixtures. It is regularly used in commercial jobs.

Receptacle

It’s a common device usually located approximately 1 foot from the floor in the wall. It supplies power to lamps, TVs, appliances, cellphone chargers, vacuum cleaners, and similar.

Ground-Fault Circuit Interrupter (GFCI)

These receptacles are typically found near wet locations. It has a “test” and “reset” button to assure the device is working properly. It’s intended to de-energize a circuit or a portion of a circuit when a current to ground exceeds the values for Class A device, protecting personnel.

Single-Pole Switch

It is controlled by 1 switch near the doorway. It is used when you have a light controlled by a single switch.

Three-Way Switch

It is used at each location to control a light in 2 locations. For example, a light over a set of stairs going into a basement and there is a switch at the top and bottom of the steps.

Four-Way Switch

The installation include 2 three-way switches, but any switches required beyond 2 locations requires this installation.

Arc-Fault Circuit Interrupter (AFCI)

It provides protection from the effects of arc faults. This device recognizes the characteristics or an arc fault and will de-energize the circuit when an arc fault is detected.

Conductor

Allows electrical current to flow in 1 or more directions like metal wire, copper, and aluminum. 3 Types of conductors are bare, covered, and insulated.

Equipment Grounding Conductor (EGC)

It’s the conductive path that provides a ground-fault current path and connects normally noncurrent-carrying metal parts of equipment together and to the system grounded conductor, to the grounded electrode conductor, or both.

National Fire Protection Association (NFPA)

Producers of codes for many safety concerns. This code is designed to protect workers from hazards of working on or near energized conductors and circuit parts.

Globally Harmonized System (GHS)

An international system of safety information for chemicals and other hazardous items.