electrical safety for non-electrical workers (unqualified)

North Slope Training Cooperative

© North Slope Training Cooperative—revised May 2012. All rights reserved.

Electrical Safety for Non-Electrical Workers (Unqualified)

NSTC-10

© North Slope Training Cooperative—May 2012. All rights reserved.

Course Overview

2


Administration and Safety

Emergency Procedures

Restrooms/Breaks/Smoking

Safety Minute

3


Introductions

Name

Company and/or position

Experience working in areas where there are potential hazards from energized equipment, or power tools.

4


Goal

To provide non-electrical (unqualified) employees with the knowledge to recognize electrical hazards and take appropriate measures to protect themselves against injury or death.

5


Objectives

Distinguish between an affected person, unqualified person, and qualified person as it pertains to electrical safety.

List the potential electrical injuries/hazards related to using power tools and working around energized equipment.

Explain basic electrical concepts that are important to understanding why electricity is dangerous.

6


Objectives

Explain safe work practices for using power tools/equipment and working around energized equipment.

Explain the general rules for responding to an electrical emergency.

7


Standards and Terms

8


Electrical Standards

OSHA 29 CFR 1910.331-333: Subpart S: Safety Related Work Practices for Qualified and Unqualified Persons

OSHA 29 CFR 1926 Subparts I and K

National Electrical Code (NFPA 70)

Alaska Safety Handbooks (ASH & BP ASH)

ASH, pages 22-24; 28-29; BP ASH, pages 59-61; 214

9


Key Terms

What are the correct definitions of the following terms and why are they important? Which of these definitions fit your job responsibilities?

Affected Employee

Unqualified Person

Qualified Person

ASH, page 189, 195; BP ASH, page 237, 244

OSHA 29 CFR 1910.331(a)

10


Basic Electrical Concepts

11


How Electricity Works

When you turn on a light switch, current flows from the generating source through a conductive material (wires) to the area of demand or load (light bulb).

Current will only flow if a complete path or circuit is provided from the source, through the load, and back to the source.

The electrical pressure that causes current to flow is voltage. A conductor connected to a power (voltage) source is said to be energized.

12


Electricity Flow 13


Simple Electrical Circuit Open 14


Simple Electrical Circuit Closed 15


Ohm’s Law V= IR

For electrons to move in a particular direction, a potential difference must exist between two points within the circuit. This difference is measured in volts (V).

Current (I), the continuous movement of electrons past a given point, is measured in amperes.

All conductors resist the flow of current, some more than others. Resistance (R) is measured in ohms.

16


Types of Current

Direct current (DC) flows in one direction with constant pressure (voltage).

Examples: battery-operated tools or equipment; motors used in special process applications

Alternating current (AC) periodically reverses it’s direction of flow according to a cycle. In the U.S., AC current is 60 cycles per second.

Examples: circuits for lights, appliances, tools and equipment

17


Conductors

Electrical conductors are low resistance materials which readily allow electrons to pass through.

Examples are copper, aluminum, iron, steel, water with impurities, electrolytes, and concrete.

Because all conductors resist electron flow to some extent, when the current overcomes the resistance, it creates heat.

The photo above shows copper wires covered by a glass insulator.

18


Insulators

Because conductors get hot, they need to be insulated to prevent fires.

Materials such as glass, ceramics, plastics, rubber-like polymers, and porcelain have a natural resistance to electrical flow and make good insulators.

Copper wires sheathed in plastic and enclosed in an aluminum cable

Copper wires sheathed in plastic

19


Electrical Safety Devices

Circuit breakers and fuses: Automatic tripping devices which control the amount of current flowing in the circuit and prevent overloaded circuits which could cause fires. They are designed to protect the equipment from damage.

Ground fault circuit interrupter (GFCI): A safety device which detects current leakage from a circuit to ground (ground fault) and shuts off the current. It is designed to protect the person not the equipment.

20


Bonding

Bonding is the process of connecting two or more conductive objects to each other by means of a conductor to minimize potential differences between conductive objects. Bonding equalizes the potential between objects.

BP ASH, pages 198-199; 238

21


Grounding

Grounding is the process of connecting one or more conductive objects to the ground to minimize potential differences between objects and the ground. Grounding dissipates an electric charge to ground.

BP ASH, pages 198-199; 241

22


Bonding and Grounding

This is an example of grounding two objects with the earth and bonding them to each other.

BP ASH, pages 198-199; 238; 241

23


Electrical Hazards and Injuries

24


Potential Electrical Hazards

Contact with overhead transmission lines

Defective insulation – exposed wiring or electrical parts

Overloaded circuits

Ungrounded or improperly grounded circuits

Wet conditions

Defective tools and equipment

Flammable atmosphere

Inadequate wiring

25


Electrical Shock

Electrical shock occurs when a person’s body completes an electrical circuit by touching:

an energized wire and an electrical ground.

an energized wire and another wire of a different voltage.

a metallic part that is “hot” because it’s touching an energized wire and is in contact with the ground.

A energized wire while perspiring or standing on wet ground.

26


Electrical Shock

Electrical shock can cause:

a slight tingling or total immobility

severe burns

internal bleeding, tissue, and muscle damage

cardiac arrest and death (electrocution)

Electrical shock is often the beginning of a chain of events which may include falls, cuts, broken bones.

27


Electrical Shock

The severity of injury from electrical shock depends on the:

amount of current flowing through the body.

amount of voltage.

path of the current through the body.

length of time the body is part of the circuit.

resistance of the skin.

28


Arc Flash or Blast

Fire or explosion can occur if the atmosphere contains a flammable or explosive mixture.

An arc flash or blast can result in burns, blindness, hearing loss, and shrapnel wounds.

Arc flashes and/or blasts occur when high amperage currents jump from one conductor to another through air, generally during opening or closing circuits or when static electricity is present.

29


Safe Work Practices

30


Equipment Inspections

Inspect all equipment, appliances, extension cords or plug-connected hand tools for any sign of damage or missing parts prior to use.

Tag defective appliances, tools, and extension cords, and turn them in for repair.

When electric-driven equipment becomes unsafe to operate, it shall be locked and tagged out immediately.

ASH, page 22BP ASH, page 59

31


Equipment Repairs

Only qualified and authorized personnel shall:

repair, adjust, or install electrical equipment and wiring systems.

make repairs to extension cords and cords on electrical tools.

ASH, page 22BP ASH, page 59

32


Extension Cords

Use only three-wire, grounded, extension cords.

Electrical cables and/or extension cords should be run overhead and not laid on the ground or deck (ASH, page 24; BP ASH, page 60).

High current equipment or appliances should be plugged directly into a wall outlet whenever possible.

33


Extension Cords

All extension cords should be plugged into:

a GFCI outlet,

a GFCI built into the cord, or

a GFCI adapter used between the wall outlet

and the cord plug.

34


Power Tools

All electrical equipment and tools must have an on and off switch and may not be turned on or off by plugging or unplugging the supply cord at the power outlet.

All portable electric tools shall be used with ground fault circuit interrupters (GCFI) or be included in an assured grounding program.

Avoid contact between two connections on a battery.

ASH, page 22 BP ASH, page 59

35


Power Tools and Equipment

Motor overloads may be reset once after an Operator has checked the motor for any unusual conditions such as hot bearings or motor. Notify facility electrician of the trip.

Motor starts per hour shall not exceed the manufacturer’s specifications.

Any feeder or branch circuit breaker trips shall be brought to the attention of the Supervisor or facility electrician.


36


Lighting

A Hot Work Permit is required to install or use non-explosion proof temporary lighting in a classified area.

All portable lights shall be used with ground fault circuit interrupters (GCFI) or be included in an assured grounding program.

Low voltage lights (50 volts or less) may be used in lieu of lights with GCFI.

Use approved lighting in wet and classified areas ASH, page 22

BP ASH, page 59

37


Working Near Energized Equipment

Portable ladders, used for electrical work, shall have non-conductive side rails.

Equipment operating within 15 feet of any un-insulated power distribution system line, structure, guywire or switch yard requires prior clearance by the appropriate Company Supervisor.

ASH, pages 23-24 BP ASH, pages 60-61

38


Working Near Energized Equipment

Maintain minimum 4 foot NEC required clearances in front of all switchgear and motor control centers for access.

If these clearances are not present, the switchgear must be appropriately marked with warning labels.

These spaces are not intended for storage areas and must be kept clear.


39


Avoiding Other Electrical Hazards

Avoid overloading circuits by plugging in multiple appliances (microwave ovens, toasters, space heaters, coffeepots) into the same outlet.

Remove jewelry and other conductive objects before starting work.

ASH, pages 6, 11 BP ASH, pages 30, 38

40


Electrical Lockout Tagout

If an employee can be exposed to contact with energized electrical equipment, the circuits energizing the parts shall be isolated by lockout tagout procedures (OSHA 1910.333(b)(2) ).

Only authorized personnel may perform lockout and tagout work on electrical equipment.

Affected employees will be notified when lockout and/or tagout activities are being performed in their work area.

ASH, page 189 BP ASH, pages 237

41


Personnel Restrictions

Only authorized personnel shall be permitted in electrical distribution switchgear rooms and enclosures.

Equipment operating within 15 feet of any un-insulated power distribution system line, structure, guy wire, or switch yards requires prior clearance by the appropriate Company Supervisor.


42


Personnel Restrictions

Only a qualified electrician may bring a conductive object closer than 15 feet to unguarded, energized overhead lines.

Power distribution switchgear shall be operated only by qualified personnel.

Review the electrical safety procedures in the Alaska Safety Handbooks.


43


Responding to an Electrical Emergency

44


Follow the Emergency Action Plan

Remain calm and keep your distance.

Turn off the power.

Call for help immediately.

Do not touch the victim.

Trained personnel may administer First Aid or CPR when it is safe to touch the victim.

45


Fire Extinguishers

Approved fire extinguishers should be provided near electrical breaker panels and distribution centers.

Water-type extinguishers are not intended for use on electrical fires and shall not be located closer than 50 feet from electrical equipment.

Do not use a fire extinguisher unless you are trained to do so.


46


Summary

Standards and Terms

How Electricity Works

Electrical Hazards and Injuries

Safe Work Practices

Responding to Electrical Emergencies

47

electrical safety for non-electrical workers (unqualified)

Documents