Industrial Electrical

Safety

John Newquist

Draft 3 14 2015

Dec 2013

Oct 2013

June 2014

• 42-year-old Lynden Endress was washing

cattle on his farm.

• That's when the power washer he was using

short-circuited, electrocuting him.

November 2014

• Dietrich believes the man was

electrocuted by his wedding

ring after it made contact with a

copper wire in the back of the

machine.

• Albert Washington, his brother-

in-law, told officers that he

turned the power off to the

room. He asked for the power

to be put back on to test the

machine – and then when a

fault was noticed he tried to fix

it without turning the electricity

off again, at which point he was

electrocuted, according to the

Daily Mail.

March 2014

Top 10 Most Cited Standards

(General Industry Only)

1. Hazard Communication

2. Respiratory Protection

3. Lockout/Tagout

4. Powered Industrial Trucks

5. Electrical, Wiring Methods

6. Machine Guarding

7. Electrical, Systems Design

8. Powered Transmission Apparatus

9. Personal Protective Equipment

10. Abrasive Wheel Machinery

March 2015

• Issues?

Who needs

training?• 1910.332(a)

• Employees in occupations listed

in Table S-4 face such a risk

and are required to be trained.

Other employees who also may

reasonably be expected to face

comparable risk of injury due to

electric shock or other electrical

hazards must also be trained.

• At a minimum, be trained in

and familiar with the following:

• The skills and techniques

necessary to distinguish

exposed live parts from other

parts of electric equipment.

• The skills and techniques

necessary to determine the

nominal voltage of exposed live

parts, and

• The clearance distances

specified in 1910.333(c) and the

corresponding voltages to

which the qualified person will

be exposed.

Table S4

• Typical Occupational

Categories of Employees

Facing a Higher Than Normal

Risk of Electrical Accident

• Blue collar supervisors

• Electrical and electronic

engineers

• Electrical and electronic

equipment assemblers

• Electrical and electronic

technicians

• Electricians

• Industrial machine operators

• Material handling equipment

operators

• Mechanics and repairers

• Painters

• Riggers and roustabouts

• Stationary engineers

• Welders

Ohm’s Law

• The equations of Ohm’s Law

are:

• Voltage = Current times

Resistance

• Current equals Voltage divided

by Resistance,

• Resistance equals Voltage

divided by Current.

• 13,800 Volts / 1000 Ohms =

13.8 Amps

• 480 Volts / 0.1 Ohms = 4,800

Amps

• 480 Volts / 0.01 Ohms = 48,000

Amps

Determine the Current

• Voltage is 120 volts. Resistance is 12 ohms.

Current, then, is _______ amps.

• Voltage is 480, resistance is 1 Ohm =

_____ amps

• Voltage is 220 resistance is 2200 Ohm =

_____ amps

Electrical Current Effect

• 1 mA threshold for feeling

• 10-20 mA voluntary let-go of circuit

impossible

• 25 mA onset of muscular contractions

50-200 mA ventricular fibrillation or

cardiac arrest • E. A. Lacy, Handbook of Electronic Safety Procedures, Prentice- Hall: Englewood Cliffs,

New Jersey (1977)

Electricity and Conductors

• To flow, electricity must have a complete

path back to earth

• Electricity flows through conductors

• Water, Metal, the human body can be

conductors

• Insulators are not conductors

Ventricular Fibrillation

• When the heart is in ventricular fibrillation, the musculature of the ventricles undergoes irregular, uncoordinated twitching resulting in no net blood flow. The condition proves fatal if not corrected in a very short space of time.

120 Volts on the body

• If your body resistance

is 100,000 ohms, then

the current which

would flow would be:

• I = 120 volts/100,000

ohm or 1.2 mA – able

to feel it

• Current =

Volts/Resistance

• But if you are sweaty

and barefoot, then

your resistance to

ground might be as

low as 1000 ohms.

Then the current

would be:

• I = 120 V/1000 ohm

or 120 mA –

ventricular fibrillation

National Electric Code

• The National Fire Protection Code, got its first electrical section in 1897

• Concern about many electrical fires and conflicting codes

Knob & Tube

• 1881 NY Board of fire underwriters

• When it becomes necessary to carry wires through partitions and floors, they must be secured against contact with metal, or other conducting substance, in a manner approved by the Inspector of the Board.

Electrical Grounding

• 1928 NEC "Grounding required in conductive locations such as in basements or in walls containing metal lath, even if the equipment was fed by Knob and Tube wiring, nonmetallic cable lacking a grounding conductor.

• Current travels both paths. Grounding involves providing

a conductor to carry most of

the current into the ground

rather than into a body.

GFCI’s –1971 NEC

The GFCI operates by sensing the difference between the currents in the Hot and Neutral conductors. Under normal conditions, these should be equal. Will shut off at 5 mA in 1/40th of a second.

Double Insulated

• Insulated from shock

• Square with square

• Watch out for no lab

testing

Power Taps

• 29 CFR 1910.305(g)(1)(iii)

reads as follows:

• "Unless specifically permitted

in paragraph (g)(1)(i) of this

section, flexible cords and

cables may not be used:

• (A) As a substitute for the

fixed wiring of a structure.

Fluorescent Lighting

• Most common cause of electrical death among electricians

• Changing ballast while live.

• Worker not de-energizing circuit nor wearing any PPE.

Working Live

• Shall be de-energized before the employee works on or near them, unless the employer can demonstrate that de-energizing introduces additional or increased hazards or is infeasible due to equipment design or operational limitations.

• Testing live to find fault or short is common reason.

Insulated leads alones are not safe. Wear rated gloves.

#1 - Boxes with unused

openings

• 1910.305(b)(1)

Knockout Missing Missing Dead Fronts

Note: Circuit breakers are designed to

protect property not people.

#2 – Exposed live parts over 50 Volts

• 1910.303(g)(2)(i)

Exposed wiring Missing electrical housing

#3 – Missing covers

• 1910.305(b)(2)

Missing cover Receptacle w/o cover

#4 - Hanging pendant boxes

• 1910.305(g)(1)(iii)

Box has strain relief and no knockouts Knockout can get pushed

into box

#5 – Missing Grounding

Conductor

• 1910.304(f)(4)

Missing ground prongMissing ground prong

#6 – Disconnects not labeled

• 1910.303(f)

Label is tattered No labels on disconnects

#7 – Strain relief

• 1910.305(g)(2)(iii)

Wire pulled out of shredder Missing on strain relief

#8 – Equipment not used per listing

• 1910.303(b)(2)

Box used as an extension cord Receptacle box not mounted

Nov 2013

• Citation 2 Item 1 Type of Violation: Willful

• 29 CFR 1910.303(b)(2): Listed or labeled electrical equipment was not

used or installed in accordance with instructions included in the listing

or labeling:

• On or about May 24, 2013, and at times prior thereto, Spiral "final"

department, employees are allowed to use foreign material to operate

control panels.

• Employees are using makeshift instruments, including but not limited

to clip binders and welding wire bent in the shape of shepherd's hooks

to override the "forward" limit switch on the pipe conveyor console

panel, so that the pipe can continue horizontally down the conveyor

and the incoming pipe can immediately be worked on to reduce

workload buildup.

• The practice of overriding the limit switch on the console panel

exposes employee(s) to hazards associated with being struck by and

caught-in between conveyed piping, stopping blocks and other

stationary or transported objects.

#9 – 3’ Clear spaces

• 1910.303(g)(1)(ii)

Panel box blocked Storage in front of

panel box

#10 – Electrical Free of Hazards

• 1910.303(b)(1)

Ground prong stuck in

receptacle

Open wiring spliced out of box

Receptacles

• Receptacles will have

hot, neutral, and a

grounding conductor

Voltage Detectors

• A Voltage detector

will sense the

magnetic field around

an extension cord.

Insulated Gloves

Electrical gloves can protect the worker who must test circuits live.

Gloves can be bought for work with voltages under 500 volts. These are Class

00 gloves.

Gloves must be sized for each employee.

Test every six months.

Fuse Pulling

Worker died when shocked pulling out barrel fuse with pliers

Electrical circuits must be locked out before doing any work on the

circuits if possible.

Sign Shock

• Worker found unconscious taking out electric

receptacle while still energized. Breakers were

not locked out. No labels

Air Handler

Worker touched an energized horizontal heating coil

Daily Checks

• Cord and plug connected

equipment should be check

daily before use.

• 1910.334(a)(2)(i)

• Portable cord and plug

connected equipment and

flexible cord sets (extension

cords) shall be visually

inspected before use on any

shift for external defects

Reverse

Polarity

• For example, if an internal fault

should occur in the wiring as

shown in the figure below, the

equipment would not stop when

the switch is released or would

start as soon as a person plugs

the supply cord into the

improperly wired outlet. This

could result in serious injury.

On October 30, 2004,

Employee #1 was apparently

trying to use a portable electric

grinder at a work site when he

was electrocuted from

ungrounded and reverse

polarity electrical sources.

Capacitors

• Pleasant Prairie WI

• OSHA’s investigation found the temp

worker had inadvertent contact with

electrical equipment while trouble-

shooting an electrical failure on a heat-

sealing machine.

• Company failed to require personal

protective equipment for employees

working near exposed, energized

electrical parts.

• The company also did not develop

procedures to de-energize circuits and

equipment safely or ensure stored

energy capacitors were grounded.

Clear Space again

• 1926.403(i)(1)

• Sufficient access and working

space shall be provided and

maintained about all electric

equipment to permit ready and

safe operation and maintenance

of such equipment.

Classified Locations

• Combustible dust

• Exposed wiring.

Quiz

• What mA causes muscle contractions? ____

• A GFCI will shut off in ____ of a second.

• When the musculature of the ventricles undergoes

irregular, uncoordinated twitching resulting in no

net blood flow is called _______ _______

• Live parts over ___ volts need to be guarded.

• ___ feet of clear space must be maintained in front

of electrical panels

ELECTRIC ARC FACTSn TYPICALLY LASTS

LESS THAN A SECOND

n EXTREMELY HIGH

RADIANT ENERGY

n EXPLOSIVE IN NATURE

• CAN IGNITE AND/OR

MELT

CONVENTIONAL

WORK CLOTHING

Electrical Statistics• As many as 80 percent

of all electrical injuries are from an arc-flash contact and ignition of flammable clothing.

• 2,000 people are admitted to burn centers

• Source: Cooper Bussmann

Arc Flash Incidents• Estimated 5-10 arc flash

incidents per day

• Numerous fatalities per year

• Estimates as to costs of burn injury medical (skin grafts, therapy )and related costs (replacement worker, rehabilitation,) average between 1.0 and 4 million dollars.

• And then we have a social cost!!!

Now which of you has seen this

label?

New Requirement

If the marking is not there.

• The system was turned over without the appropriate hazard warnings.

• It is not in compliance with the the 2002 National Electrical Code

• If there is an Arc Blast/Flash event what is your exposure???

An arc flash is a short circuit

through the air

The temperature of an arc can

reach approximately 35,000

degrees Fahrenheit or about

four times as hot as the surface

of the sun.

Causes of Electric Arcs

• Dust and impurities

• Corrosion

• Condensation of vapor and water dripping

• Accidental touching

• Dropping tools

• Over-voltage across narrow gaps

• Failure of insulating materials

• Improperly designed or utilized equipment

• Improper work procedures

Electrical Processes Causing Flashes• Removing or installing

circuit breakers or fuses

• Voltage testing

• Working on control circuits

when energized parts

exposed

• Applying safety grounds

• Racking circuit breakers

• Racking starters

• Removing bolted covers

PPE

PPE will depend on which boundary and task you are in.

FR clothing must be work first at Category 1 work.

Power Lines

• 10 foot safe clearance.

• Avoid storing material

under the lines.

Summary

• Grounding involves

providing a conductor

to carry most of the

current into the ground

rather than into a

body.

Summary

• Water and other

liquids are good -

conductors of

electricity.

Lastly

• A three-pronged plug

should never be used

in a two pronged

outlet

Questions?

This is very unsafe!