Download Electrical Safety-Arc Blast

Electrical Safety and
Electrical Safe Work
Practices
EHS Course #525
Reference EHS Electrical Safety
Procedure 75-44
1
Why Electrical Training?
2
What Problems Do You See
in Your work area?
• Damaged plug
• Missing ground
pin
• Shorted out – the
missing prong was
found still in the
outlet...
• Why is a missing
ground pin a
problem?
3
What Problems Do You See
in Your work area?
• Damaged GFCI
outlet
• Why didn’t the
GFCI prevent the
damage?
4
What Problems Do You See
in Your work area?
• Spliced and
taped cord on a
lamp – fire and
electrocution
hazard
5
Don’t do this at home.....
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Home Electrical Safety
• Never use lights with frayed cords, loose or bare wires, cracked or
empty sockets.
• Do not connect more than 3 light sets together & do not overload
extension cords (use an outlet strip with built-in overload protection).
• Turn off all Christmas lights prior to leaving your
home or going to bed.
• Use only equipment that is UL listed and in good repair.
• Do not use candles on or near your tree.
• Test your smoke and carbon monoxide detectors, replace batteries.
• If outdoors, use only electrical decorations certified for outdoor use &
keep clear from snow and water & use GFCI protected circuit.
• Plug lights & decorations into circuits protected by GFCIs (ground
fault circuit interrupters).
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Installations
• All installations at BD shall meet the following code
minimum requirements:
– NFPA/NEC 70 (National Electrical Code)
– NFPA 79 (Electrical Standard for Industrial Machinery)
NOTE: If you don’t know what these two codes
are, AND what they require, you have no business
working on electrical equipment or opening an
electrical cabinet…
• ONLY qualified Facilities Electricians may work on
building electrical systems…
• Only qualified Electro-mechanics and qualified
Engineers may work on production equipment electrical8
systems and components
Why Follow the Rules?
• Electrical shock
– What is the highest voltage on production
equipment here at BD – Sandy?
– When was the last electrical shock incident (other
than static electricity) at BD – Sandy?
• Arc Flash hazard
• Electrical fires
• Electrical burns
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ELECTRICAL HAZARDS
• Misnomer: Electricity flows through the path
of least resistance. (It flows through ALL
paths…)
• Electric shock occurs when the human body
becomes part of the path through which
electrical current flows.
– The direct result can be electrocution.
– Burns can result when a person touches electrical
wiring or equipment that is energized
– The indirect result can be injury resulting from a fall
or movement into machinery because of a shock.
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Arc Flash/ Arc Blast
• Occurs when high amperage current jumps a
gap (short circuit) – such as when uninsulated tools are being used on live
electrical circuits...
• Arc Flash / Arc Blast injuries was the number
one source of electrical injuries, and has been
for many years…
• An arc blast can occur when electrical
cabinets/panels are open
– Temperatures can be as high as 35,000 F
– Metal, Molten metal, or other objects
– Pressure Wave
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ELECTRICAL HAZARDS
• Explosions: Occur when electricity provides an
ignition source for an explosive mixture in the
air.
– Flammable vapors
– Dust (plastic dusts, grain dust, other organic material, metal
dusts,etc)
• Fires: Electricity is the most common cause of
fires both in the home and in the workplace.
– Defective or misused electrical equipment is a major cause.
• Electrically Classified Areas and Equipment:
Never substitute parts, never make
modifications without an Engineering Review!
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ELECTRIC SHOCK
Effects of electric
shock
depend on:
-- Current & voltage
-- Resistance
-- Path through
body
-- Duration of shock
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CURRENT &
VOLTAGE
As alternating current increases:
• Tingling gives way to muscle contractions
• Pain develops
• Control of muscles becomes increasingly
difficult
• At 15 mA, victims cannot let go of the
conductive surface
• At 70 mA, ventricular fibrillation of the heart
occurs (a typical circuit is 15 amps plus)
• Death follows in a few minutes
• Heavy current flow can also result in severe
burns (internal & external) & heart paralysis
14
BY-STANDERS AND
APPROACH DISTANCES
(AKA Electric Shock Protection Boundaries)
Limited Approach Boundary
Nominal System
Voltage Range,
Phase to Phase
Restricted
Approach
Boundary
Prohibited
Approach
Boundary
Exposed Movable
Conductor
Exposed Fixed
Circuit Part
36 in
36 in
Avoid Contact
Avoid Contact
50-300
10 ft 0 in
3 ft 6 in
Avoid contact
Avoid contact
301-750
10 ft 0 in
3 ft 6 in
1 ft 0 in
1 in
751-15 kV
10 ft 0 in
5 ft 0 in
2 ft 2 in
7 in
15.1 kV-36 kV
10 ft 0 in
6 ft 0 in
2 ft 7 in
10 in
36.1 kV-46 kV
10 ft 0 in
8 ft 0 in
2 ft 9 in
1 ft 5 in
Less than 50
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General Electrical
Concerns
• Extension cords can be made ONLY by
“Qualified Individuals” (see above…)
• Do not use gang plugs (wall mount box on
end of extension cord with 2 or more outlets
installed…)
• Do not use cords with broken ground prongs
• Do not piggy-back surge protectors
• Do not use zip cords (light weight household
type extension cords that do not have a
secondary insulation sheath)
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General Electrical
Concerns
• Keep all electrical equipment clear from
water and moisture
• Building Circuit Breakers can be reset
ONLY by Qualified Facilities Personnel
• The only persons authorized to open
and do any work in an electrical cabinet
on production equipment are:
– Qualified Electro-mechanics
– Qualified Engineers
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Don’t do this at Home....
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Did I Mention there is a
QUIZ???
• The quiz is in the following location:
S:\Safety\Training 2008\Dec - Electrical
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