Utilization Equipment Overview

Utilization Equipment

• Utilization equipment consists of electrical or electronic machines designed for specific purposes.
• Examples include motors, air conditioning units, refrigeration systems, heating units, signs, industrial machinery, cranes, hoists, elevators, and escalators.
• Appliances are a type of utilization equipment designed for specific functions like cooking, cleaning, cooling, or heating.
• Seven main categories of appliances include: Fixed, Stationary, IT, Movable, Portable, Cables & Charges, and Hand Held.
• Fixed Appliances are permanently attached, such as built-in cooktops or ovens.
• Stationary Appliances are situated and used at a specific location but can be moved, like refrigerators, washing machines, or dryers.
• Portable Appliances are easily carried or moved, such as hair dryers or toasters.
• An Electrical Device is a component in an electrical system designed to carry, but not use, electricity. Examples include switches, receptacles, and relays.

Outlets, Receptacles, and Plugs

• An outlet is the location in a branch circuit where electricity is used.
• A receptacle is a female connecting device with slotted contacts installed at an outlet.
• A plug is a male connecting device inserted into a receptacle to connect to an electrical circuit.
• Plugs are typically connected to flexible cords attached to portable appliances, lights, or equipment.
• NEMA designates the different types of receptacles and plugs based on their specifications.
• Receptacle screw terminals are color-coded:
  • Brass-colored screws: Undergrounded conductor
  • Silver-colored screws: Grounded or neutral conductor
  • Green-colored screws: Equipment grounding conductor
• Receptacles marked "CO/ALR" can connect to copper, aluminum, or copper-clad aluminum conductors.
• Receptacles marked "CU/AL" were formerly allowed for use with copper or aluminum conductors but can now only connect to copper conductors.

Switches

• A switch is a device between electrical conductors that opens or closes a circuit to safely and intentionally control electrical flow.
• Switches are rated by purpose, voltage, amperage, and classified for AC or DC.
• Safety switches are designed to reduce contact with bare electrical conductors and have current interrupting capability.
• Two main categories of safety switches are:
  • Heavy-duty safety switches: For heavy industrial, commercial, and institutional applications requiring safety, performance, and continuity. These are enclosed and may be fused or unfused.
  • General duty safety switches: For industrial, general commercial, and residential applications where economy is important. They are used on lighting, heating, appliance, and intermittent motor loads.

Switching Terminology

• POLE: Refers to the number of conductors the switch controls.
• THROW: Refers to the number of operations the switch can perform.
• Single-pole, single-throw (SPST) switch: A simple on/off switch controlling a single undergrounded conductor in a circuit.
• Single-pole, double-throw (SPDT) switch: Diverts current from one conductor path to another.
• Three-way switch (S3): A special SPDT switch allowing control of an installation from two locations.
• Double-pole, single-throw (DPST) switch: Opens and closes two conductors in a circuit. Equivalent to two SPST switches controlled by a single mechanism.

Conductors

• An electrical conductor is any material that conducts electrical current.
• Wire is a common conductor and is classified by a wire gauge standard based on cross-sectional area in circular mils (cmil).
  • 1 mil = 1/1000 inch
  • 1 cmil = cross-sectional area of a 0.001 inch diameter circle
• Electrical conductors can be solid or stranded:
  • Solid conductors: A single solid wire.
  • Stranded conductors: Consist of smaller wire strands.

Buses

• A bus (also called a bus bar) is an electrical conductor, typically copper or aluminum, that serves as a common connection for two or more electrical circuits.
• Buses are commonly found in panel boards, switchboards, and other power distribution equipment.

Conductor Material

• Silver is the best electrical conductor material, having the least resistance, though superconductors are an exception.
• Copper and aluminum conductors are widely used in building wiring installations, providing a balance between good conductivity and cost effectiveness.