Industrial electrical safety

Industrial Electrical Safety
John Newquist

1. Industrial Electrical
Safety
John Newquist
Draft 3 14 2015

2. Dec 2013

3. Oct 2013

4. June 2014
•42-year-old Lynden Endresswas washing
cattle on his farm.
•That's when the power washer he was using
short-circuited, electrocuting him.

5. 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.

6. March 2014

7. 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

8. March 2015
•Issues?

9. 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.

10. 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

11. 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

12. 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

13. 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)

14. 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

15. 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.

16. 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

17. National Electric Code
•The National Fire
Protection Code,
got its first
electrical section
in 1897
•Concern about
many electrical
fires and
conflicting codes

18. 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.

19. 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.

20. 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.

22. Double Insulated
•Insulated from shock
•Square with square
•Watch out for no lab
testing

23. 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.

24. Fluorescent Lighting
•Most common cause
of electrical death
among electricians
•Changing ballast while
live.
•Worker not de-
energizing circuit nor
wearing any PPE.

25. 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.

26. #1 -Boxes with unused
openings
•1910.305(b)(1)
Knockout Missing
Missing Dead Fronts
Note: Circuit breakers are designed to
protect property not people.

27. #2 –Exposed live parts over 50 Volts
•1910.303(g)(2)(i)
Exposed wiring Missing electrical housing

28. #3 –Missing covers
•1910.305(b)(2)
Missing cover
Receptacle w/o cover

29. #4 -Hanging pendant boxes
•1910.305(g)(1)(iii)
Box has strain relief and no knockouts
Knockout can get pushed
into box

30. #5 –Missing Grounding
Conductor
•1910.304(f)(4)
Missing ground prong
Missing ground prong

31. #6 –Disconnects not labeled
•1910.303(f)
Label is tattered No labels on disconnects

32. #7 –Strain relief
•1910.305(g)(2)(iii)
Wire pulled out of shredder
Missing on strain relief

33. #8 –Equipment not used per listing
•1910.303(b)(2)
Box used as an extension cord
Receptacle box not mounted

34. Nov 2013
•Citation 2 Item 1Type 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.

35. #9 –3’Clear spaces
•1910.303(g)(1)(ii)
Panel box blocked
Storage in front of
panel box

36. #10 –Electrical Free of Hazards
•1910.303(b)(1)
Ground prong stuck in
receptacle
Open wiring spliced out of box

37. Receptacles
•Receptacles will have
hot, neutral, and a
groundingconductor

38. Voltage Detectors
•A Voltagedetector
will sense the
magnetic field around
an extension cord.

39. Insulated Gloves
Electrical glovescan 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.

40. Fuse Pulling
Worker died when shocked pulling out barrel fuse with pliers
Electrical circuits must be lockedout before doing any work on the
circuits if possible.

41. Sign Shock
•Worker found unconscious taking out electric
receptacle while still energized. Breakers were
not locked out. No labels

42. Air Handler
Worker touched an energized horizontal heating coil

43. Daily Checks
•Cord and plug connected
equipment should be check
dailybefore 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

44. 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.

45. 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.

46. 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.

47. Classified Locations
•Combustible dust
•Exposed wiring.

48. 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

49. ELECTRIC ARC FACTS
nTYPICALLY LASTS
LESS THAN A SECOND
nEXTREMELY HIGH
RADIANTENERGY
nEXPLOSIVE IN NATURE
•CAN IGNITE AND/OR
MELT
CONVENTIONAL
WORK CLOTHING

50. 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

51. Arc Flash Incidents
•Estimated 5-10arc 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!!!

52. Now which of you has seen this
label?

53. New Requirement

54. 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???

55. 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.

56. Causes of ElectricArcs
•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

57. 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

58. PPE

59. PPE will depend on which boundary and task you are in.
FR clothing must be work first at Category1 work.

60. Power Lines
•10 foot safe clearance.
•Avoid storing material
under the lines.

61. Summary
•Grounding involves
providing a conductor
to carry most of the
currentinto the ground
rather than into a
body.

62. Summary
•Water and other
liquids are good -
conductors of
electricity.

63. Lastly
•A three-pronged plug
should never be used
in a two pronged
outlet

64. Questions?
This is very unsafe!