Hazards and Riskswhen working with
Electricity
What is the best way to
prevent the hazards of
electricity?
Avoiding energized circuits is the safest way!
STOP
Think before taking
Action
THINK
About the
Risks and Hazards
OPTIONSDo you have options like:
LOTO (Lockout/Tagout)
PROTECTIONAre you wearing PPE?
(Personal Protective Equipment)
What are the
Hazards and Risks?
1. Shock
2. Arc Flash & Arc Blast
3. Fire Ignition
SHOCK
Shock and its EffectsImmediate:
1. Muscle contraction
2. Vital organs damaged
3. Tingling
4. Pain
5. Breathing
6. Disorientation
7. Dizziness
8. Possible death
Shock and its Effects
Long Term:
1. Memory Loss
2. Nervous disorders
3. Chemical imbalances
4. Damage to vital organs
5. Sometimes fatal
Effect of Current on the BodyMEN
• Perception Threshold
0.001 Amps (1 mA)• Painful Shock
0.009 Amps (9 mA)• Cannot Let-Go Level
0.010 Amps (10 mA)• Ventricular Fibrillation
.100 Amps (100 mA)• Heart Failure
0.5 Amps (500 mA)• Organ Burn
1.5 Amps (1500 mA)
WOMEN• Perception Threshold
0.0007 Amps (0.7 mA)• Painful Shock
0.006 Amps (6 mA)• Cannot Let-Go Level
0.010 Amps (10 mA)• Ventricular Fibrillation
.100 Amps (100 mA)• Heart Failure
0.5 Amps (500 mA)• Organ Burn
1.5 Amps (1500 mA)
Two Types of burns from Shock
Surface Burns:
Caused by entrance and exit of electrical currents through the body
Can be caused by a very small amount of current
1st degree to 3rd degree
Two Types of burns from Shock
Internal Tissue Burns:
Caused by current flowing through organs of the body
Caused by currents in excess of 1.5 amps
4th degree (internal) Internal organs Typically Fatal
How to prevent Shock
1. Place circuits in an Electrically Safe
Working Condition by Locking Out and
Tagging Out all sources.
2. Verifying that no electrical energy is
present.
NFPA 70 - NEC
1. The original and primary mission of the
NFPA 70 – NEC covered installation of
electrical systems.
2. The NFPA 70 – NEC does NOT
address the other hazards of electricity.
Exposure to Danger
1. The NEC protects individuals from shock
hazards under normal conditions.
2. It is NOT designed to protect us from
abnormal conditions.
3. We need additional policies to protect
from abnormal conditions.
Normal Conditions
1. Panel covers in place.
2. Equipment plugged in normally.
3. Normal designed protection in place.
Abnormal Conditions
1. Panel covers removed.
2. Equipment temporarily wired.
3. Normal designed protection such as
guards, limits switches, etc. NOT in
place.
Protection from
Abnormal Conditions
The Company
NFPA 70E
OSHA
Electrical Safety Procedures Manual
Electrical Safety Training
Protection from
Abnormal Conditions
YOU
The first line of defense.
Only you can truly keep you safe.
Implement Safety Procedures Outlined in the Safety Manual.
Only you can ensure that you go home at night.
Arc Flash
&
Arc Blast
Arc Flashis a high intensity flash which
will also create a very loud
noise (blast).
The Arc Flash produces:
Electric arc that produces the highest
temperatures on earth – up to 35,000oF (4 x
temp. of the sun).
The intense heat causes the sudden
expansion of air that results in a blast.
All known materials are vaporized at this
temperature (copper expands 67,000 times,
water 1,670 times).
Arc Flash & Blast
Relative to the human body:
A 2nd degree burn threshold, or a ‘just curable
burn threshold,’ is skin temperature raised to
175oF for 0.1 second.
A 3rd degree burn threshold, or ‘incurable burn
threshold,’ is skin temperature raised to 200oF
for 0.1 second.
Eardrum damage > 720 psf
Lung damage > 1728 psf
Arc Flash & Blast
Relative to the human body:
The hazard may be small for systems of
less than 300 volts with limited fault current.
Any system over 300 volts probably has the
capability to have significant arc flash
event.
Circuit Breaker Trips
When a circuit has been de-energized by a
protective device, DO NOT manually re-
energize the circuit without first
investigating the cause. Do not perform
repetitive manual re-closing of breakers or
replacing of fuses.
Circuit Breaker Operation With Covers
on and voltages less than 600V ac rms
Safety Glasses
Natural Fiber Long
Sleeve Shirt
Natural Fiber Long Pants
Stand to the side
Fused Switch Operation With Covers
on and voltages less than 600V ac rms
Safety Glasses
Natural Fiber Long
Sleeve Shirt
Natural Fiber Long Pants
Stand to the side
FIRE IGNITION
Clothing can be ignited several feet away
unless flame resistant (FR) or arc rated
(AR) clothing is worn.
Note: Synthetics burn ‘into’ the skin when
ignited.
Clothing
There is FR (flame resistant) clothing and
AR (arc rated) clothing.
ALL clothing with an arc rating (AR) is flame
resistant (FR), but not all flame resistant
clothing has an arc rating.
Clothing
Prior to 2015, untreated cotton was
considered a safe fabric to wear.
Beginning with the change to NFPA – 70E
in 2015, arc rated (AR) clothing is required
as you will see later in this presentation.
Now that you are aware of:
shock, arc flash and arc blast,
and fire ignition, what do you do
about it?
Protect Yourself
Protect Yourself Against
1. Shock Hazard
2. Arc Flash and Arc Blast Hazard
3. Fire Ignition
SHOCK Hazard
What is required?
1. Determine the Operating Voltage of the
System.
2. Determine Shock Protection Boundaries.
3. Determine the Personal Protective
Equipment.
SHOCK Hazard
1.Determine the Operating Voltage of the
System.
SHOCK Hazard2.Determine Shock Protection Boundaries.
a. Limited Approach Boundary –
b. Restricted Approach Boundary –
Approach Boundaries
Limited Approach Boundary –
An approach limit at a distance from an
exposed energized electrical conductor or
circuit part within which a shock hazard exists.
Approach Boundaries
Restricted Approach Boundary –
An approach limit at a distance from an
exposed energized electrical conductor or
circuit part within which there is an increased
likelihood of electric shock, due to electrical
arc-over combined with inadvertent movement,
for personnel working in close proximity to the
energized electrical conductor or circuit part.
Approach Boundaries for Alternating Current Systems
Phase-to-Phase
Voltage
LimitedApproachBoundary
Fixed
RestrictedApproachBoundary
Lessthan50
Notspecified
Notspecified
50 – 150 3 ft. 6 in. Avoidcontact
151 – 750 3 ft. 6 in. 1 ft. 0 in.
Qualified Person
One who has demonstrated skills and
knowledge related to the construction and
operation of electrical equipment and
installations and has received safety
training to identify and avoid the hazards
involved.
SHOCK Hazard
3. Determine the Personal Protective
Equipment.
a. Use Voltage Rated (VR) Gloves rated
greater or equal to the voltage of the
system.
b. Use Voltage Rated (VR) Tools rated
greater or equal to the voltage of the system.
OSHA and NFPA 70E both state that
qualified electrical workers shall not be
asked to work on equipment that is ‘hot’
or ‘live’ except for two demonstrable
reasons:
1. De-energizing introduces additional
or increased hazards, like an
emergency alarm system or a ventilation
system.
2. Infeasible due to equipment design
or operational limitations, like voltage
testing for diagnostics or start up
testing. Note: This is the HVACR
trade.
Conclusion
When you work on ‘live’ circuits, you are
open to the hazards and risks of electricity.
Therefore, you need to take on the
responsibility of protecting yourself. So,
how can this be done?
NFPA 70E Hazard/Risk Categories
• Prior to 2015, NFPA 70E classified
electrical hazards and risks from 0 to 4.
• In 2015, Category 0 was eliminated.
• The name ‘Hazard/Risk’ was changed to
‘Arc Flash PPE.’
Arc Flash PPE
or
Incident Energy Analysis
Methods
How do you select the PPE?
• Prior to 2015, selection of PPE was
based on Hazard/Risk Categories 0 – 4.
• In 2015, selection of PPE is based on
either the Incident Energy Analysis
Method or Arc Flash PPE Category
Method, but not both.
How do you select the PPE?
• The Arc Flash PPE Category Method is
the simpler of the two and that is what
this program will focus on.
• Before we look at the actual categories,
let’s take a look at some tasks and find
where Arc Flash PPE is required.
Table 130.7(C)(15)(A)(a) Arc Flash Identification forAlternating Current (ac) and Direct Current (dc) Systems
Task Equipment ConditionArc Flash
PPERequired
Reading a panelmeter operatinga meter switch.
Any No
Table 130.7(C)(15)(A)(a) Arc Flash Identification forAlternating Current (ac) and Direct Current (dc) Systems
Task Equipment ConditionArc Flash
PPERequired
Normal operation of acircuit breaker (CB),switch, contactor, or
starter
All of the following:
The equipment is properly installed.The equipment is properly maintained.All equipment doors are closed and secured.All equipment covers are in place and secured.There is no evidence of impending failure.
No
One or more of the following:
The equipment is NOT properly installed.The equipment is NOT properly maintained.Equipment doors are open or NOT secured.Equipment covers are off or NOT secured.There is evidence of impending failure.
Yes
Table 130.7(C)(15)(A)(a) Arc Flash Identification forAlternating Current (ac) and Direct Current (dc) Systems
Task Equipment ConditionArc Flash
PPERequired
For Alternating Currentsystems: work on
energized electricalconductors and circuit
parts, includingvoltage testing.
Any
Yes
Any
Yes
Removal orinstallation of
CBs or switches.
Table 130.7(C)(15)(A)(a) Arc Flash Identification forAlternating Current (ac) and Direct Current (dc) Systems
Task Equipment ConditionArc Flash
PPERequired
Removal or installationof covers for equipment
such as wireways,junction boxes, and
cable trays that does not expose bare
energized electricalconductors and
circuit parts.
All of the following:
The equipment is properly installed.The equipment is properly maintained.There is no evidence of impending failure.
No
Any of the following:
The equipment is NOT properly installed.The equipment is NOT properly maintained.There is evidence of impending failure.
Yes
Table 130.7(C)(15)(A)(a) Arc Flash Identification forAlternating Current (ac) and Direct Current (dc) Systems
Task Equipment ConditionArc Flash
PPERequired
Removal of boltedcovers (to expose bare
energized electricalconductors and circuit
parts.)
Any
Yes
Yes
Opening hinged door(s)or cover(s) to expose
bare energizedelectrical conductors
and circuit parts.
Any
Table 130.7(C)(15)(A)(a) Arc Flash Identification forAlternating Current (ac) and Direct Current (dc) Systems
Task Equipment ConditionArc Flash
PPERequired
Work on control circuitswith exposed energized
electrical conductorsand circuit parts, 120 volts or belowwithout any other
exposed energizedequipment over 120 Vincluding opening of
hinged covers to gain access.
Any
No
Table 130.7(C)(15)(A)(a) Arc Flash Identification forAlternating Current (ac) and Direct Current (dc) Systems
Task Equipment ConditionArc Flash
PPERequired
Work on control circuitswith exposed energized
electrical conductorsand circuit parts,
greater than 120 V.
Any
Yes
Work on exposedenergized electrical
conductors and circuit parts of
equipment directly supplied by a
panelboard or motor control center.
AnyYes
Table 130.7(C)(15)(A)(b) Arc-Flash Hazard PPE Categories
(Panelboards or other equipment rated 240 v and below)
Parameters:
Maximum of 25 kA short-circuit current available
Maximum of 0.03 sec (2 cycles) fault clearing time
Working distance: 18 inches
Arc Flash PPE Category: 1
Arc Flash Boundary: 19 inches
Table 130.7(C)(15)(A)(b) Arc-Flash Hazard PPE Categories
(Panelboards or other equipment rated >240 v and up to 600V)
Parameters:
Maximum of 25 kA short-circuit current available
Maximum of 0.03 sec (2 cycles) fault clearing time
Working distance: 18 inches
Arc Flash PPE Category: 2
Arc Flash Boundary: 3 feet
ARC FLASH BOUNDARY
The arc flash boundary shall be the distance at which the
incident energy equals 1.2 cal/cm2
Arc Flash PPE Category 1 has a boundary of 19 inches.
Arc Flash PPE Category 2 has a boundary of 3 feet.
What does this mean?
Incident Energy
cal/cm2
Degree Burn
1.2 2nd degree burn to bare skin
Arc Flash Boundary is related to Incident Energy.
4 Ignite a cotton shirt
8 3rd degree burn to skin
Incident
Energy
cal/cm2
Degree Burn
1.2 2nd degree burnto bare skin
Arc Flash Boundary is related to Incident Energy.
CONCLUSION
PPECategory 1
PPECategory 2
19 inches 3 feet
PPE Category 1Arc Rated Clothing, Minimum Arc Rating of 4 cal/cm2
•Arc rated long sleeve shirt and pants or arc rated coverall•Arc rated face shield or arc flash suit hood•Arc rated jacket, parka, rainwear, or hard hat liner (AN)
Protective Equipment•Hard hat (for Industrial Workers)•Safety glasses or safety goggles•Hearing protection (ear canal inserts)•Heavy duty leather gloves or combination of rubber insulating gloves with leather protectors•Leather footwear (AN)
PPE Category 2Arc Rated Clothing, Minimum Arc Rating of 8 cal/cm2
•Arc rated long sleeve shirt and pants or arc rated coverall•Arc rated face shield or arc flash suit hood and arc rated balaclava•Arc rated jacket, parka, rainwear, or hard hat liner (AN)
Protective Equipment•Hard hat (for Industrial Workers)•Safety glasses or safety goggles•Hearing protection (ear canal inserts)•Heavy duty leather gloves or combination of rubber insulating gloves with leather protectors•Leather footwear (AN)
Equipment Labeling
Equipment Labeling
Equipment Labeling
GLOVES
Class of Equipment
Maximum Use
Voltage (AC)
Proof Tested (VAC)
Proof Tested (VDC)
00 500 2,500 10,000
0 1,000 5,000 20,000
1 7,500 10,000 40,000
2 17,000 20,000 50,000
3 26,500 30,000 60,000
4 36,000 40,000 70,000
Meter Requirements
CAT III or CAT IV
Who is Responsible for Electrical Safety?
Employers are required to:
Select appropriate PPE based on the hazards present or
likely to be present in the workplace.
Prohibit the use of defective or damaged PPE.
Require that employees be trained so that each affected
employee can properly use the assigned PPE.
NFPA 70E Enforcement
The practical result of complying with the safe work
practices defined in NFPA 70E is, in most cases,
complying also with the applicable OSHA
regulations.
NFPA 70E Enforcement
Compliance is not mandatory, so OSHA safety and health
compliance officers do not enforce NFPA 70E per se. But
you can be cited for not complying with the standard.
There is a growing tendency for them to rely on NFPA 70E
under the so-called ‘general duty’ clause.
NFPA 70E Enforcement
The OSHA ‘general duty’ clause as found in
Section 5 (a)(1) of the Occupational Safety and
Health Act requires employers to furnish safe
workplaces that are free from recognized hazards
that are causing, or are likely to cause, death or
serious physical harm to employees.
Response
to an
Electrical Accident
Response to an Electrical Accident
1. The first step must be to ‘TURN THE
POWER OFF’
2. Remember that Speed is Essential
3. Extinguish flames
4. Call for Help (911)
5. Begin CPR & First Aid
Response to an Electrical Accident
First Aid
a. Cool the burn with water.
b. Do not attempt to remove burned clothing.
c. Elevate burned limbs.
d. Handle the victim with care.
e. Treat for shock.
Conclusion
When you work on ‘live’ circuits, you are
open to the hazards and risks of electricity.
Therefore, you need to take on the
responsibility of protecting yourself.
VIDEOS
SHORTED
20kA circuit
100 Amp
Disconnect
Switch Gear
ExplosionPlease watch carefully as to when
the worker puts his face shield
down and the explosion.
Switch Gear
ExplosionThere are 3 workers. Watch for
the one that is squatting between
the other 2 during the explosion.
The camera on the roof saw it all.
Breaker
Disconnect
on Roof
What are some things he could have
done to better protect himself?
Tech Electrocuted Changing Air Filter
1. Heat Pump Service Call.
2. Checked out the equipment in the attic and
outside.
3. Went under the house to change the air filter.
4. Touched the air handler cabinet, became locked
and grounded by a wire that was shorted to the
air handler’s metal cabinet.
5. He was LOCKED to the air handler and after
some 15 minutes the homeowner called him.
6.When he did not answer, the owner went under
and found him and was able to knock him off the
unit and freed him.
7.The owner dragged him out and started CPR.
8.EMS arrived and continued CPR on the way to
the Medical Center, where medical staff continued
CPR, but a doctor pronounced him dead.
Tech Electrocuted Changing Air Filter
What are some things he could have
done to better protect himself?
Tech Electrocuted Changing Air Filter
A novel way of taking
a selfie that ended
badly.
YOU need to
RESPECT
electricity and
BE SAFE.
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