Chapter 1. Symbols, circuits, and safety

wiring diagram

Diagram that shows the electrical connections of all components in a piece of equipment.

one-line diagram

Diagram that uses single lines and graphic symbols to indicate the path and components of an electrical circuit.

Flammable class I

Flammable gases and vapors

Rubber insulating matting

Floor covering that provides technicians protection from electrical shock when working on electrical circuits.

Symbol

Graphic element that represents a quantity or unit.

OSHA

Occupational Safety and Health Administration

Class B fire

Oils, grease, etc...

Line diagrams are often incorrectly referred to as...

One-line diagrams

Qualified person

Person who has special knowledge of the construction and operation of electrical equipment or specific task.

The five basic components are...

Power source, conductors, a control switch, an overcurrent protection device (OCPD), and a load.

NFPA 70e

Standard for Electrical Safety in the Workplace

Hazardous location Div. 1

Substance normally present in air

Hazardous location Div 2.

Substance not normally present in air.

Separately Derived System (SDS)

System that supplies electrical power derived from transformers, storage batteries, photovoltaic (solar) systems, and generators.

What voltage of electrostatic discharge can destroy or cause damage to a solid state device?

10 Volts

What voltage level of electrostatic discharge do people begin to feel?

3000 V

An electrostatic discharge can be... volts

35,000 or more

Grounded Conductor

A conductor that has been intentionally grounded.

Grounding Electrode Conductor (GEC)

A conductor used to connect the grounded parts of a power distribution system (equipment grounding conductors, grounded conductors and all metal parts) to the NEC- approved grounding system.

Main bonding jumper (MBJ)

A connection at the service equipment that connects the equipment grounding conductor, grounding electrode conductor, and grounded conductor (neutral conductor)

power source

A device that converts various forms of energy into electricity.

GFCI (Ground Fault Circuit Interrupter)

A device that protects against electrical shock by detecting an imbalance of current in the normal conductor pathways and opening the circuit.

schematic diagram

A diagram that shows the electrical connections and functions of a specific circuit arrangement with graphic symbols.

Line (ladder) diagram

A diagram that shows the logic of an electrical circuit or system using standard industry symbols.

Overcurrent protection device (OCPD)

A disconnect switch with the circuit breakers or fuses added to provide over current protection for the switched circuit.

Pictorial Drawing

A drawing that shows the length, height, and depth of an object in one view

Safety label

A label that indicates areas or tasks that can pose a hazard to personnel and/or equipment

abbreviation

A letter or combination of letters that represents a word that is used for a device, connection, or process.

conductor

A material that has very little resistance to current and permits electrons to move through it easily.

electrical shock

A shock that results and time a body becomes part of an electrical circuit.

control switch

A switch that controls the flow of current in a circuit.

What is needed to achieve maximum ESD protection?

All components that make up the workstation should be grounded.

static electricity

An electrical charge at rest.

IEC (International Electrotechnical Commission)

An organization that develops international safety standards for electrical equipment.

Fuse

An overcurrent protection device with a fusible link that melts and opens the circuit when an overload condition or short circuit occurs.

circuit breaker

An overcurrent protection device with a mechanical or electromechanical mechanism that manually or automatically opens a circuit when an overload condition or short circuit occurs.

load

Any device that converts electrical energy to motion, heat, light, or sound.

Class C fire

electrical equipment

protective clothing

Clothing that provides protection from contact with sharp objects, hot equipment, and harmful materials.

Flammable class II

Combustible dust

Class A fire

Common combustibles that cause ashes

Grounding

Connection of all exposed non-current-carrying metal parts to the earth.

Equipment Grounding Conductor (EGC)

Electrical conductor that provides a low impedance ground path between electrical equipment and enclosures within the distribution system.

Flammable class III

Ignitable fibers or flyings

electrical circuit

Is an assembly of conductors and electrical and/or electronic devices throught which electrons flow.

electrostatic discharge (ESD)

Movement of electrons from a source to an object across a gap.

NEC

National Electrical Code

NFPA

National Fire Protection Association

PPE (personal protective equipment)

clothing or equipment worn by a technician to reduce the possibility of injury in the work area.