ASSESSING THE ARC FLASH RISK Causes of Electric Arcs Dust and - - PowerPoint PPT Presentation
ASSESSING THE ARC FLASH RISK Causes of Electric Arcs Dust and impurities Corrosion Condensation of vapor and water dripping Accidental touching Dropping tools Failure of Insulating Material Improper Design or
Dust and impurities Corrosion Condensation of vapor and water dripping Accidental touching Dropping tools Failure of Insulating Material Improper Design or Utilization Equipment Improper Work Procedures
Serious Burns occur when victim is several feet
from arc.
Spraying of molten metal at high pressure Blast pressure waves have thrown workers
across rooms or off ladders. Pressure on the chest can be higher than 2000 lbs./sq. ft.
Clothing can be ignited and burn more severely
than unclothed areas.
Hearing loss can occur where a blast can have a
magnitude as high as 140 dB at 2 feet from arc.
(Source: American Burn Association, 1991-1993 Study; Revised March 2002)
Past National Electric Code (NEC) and other safety
codes primarily concerned with protection from fire, electrocution, and shock hazard.
The 2005 NEC now has requirements for warning
labels in conjunction with a new standard, NFPA 70E-2004, Standard for Electrical Safety in the Workplace.
NFPA 70E-2004 is intended for use by employers,
employees, and OSHA.
NFPA 70E-2004 and IEEE Std 1584-2002 provide
guidance on implementing appropriate safety procedures and arc flash calculations.
Although OSHA doesn't directly state what to do about
arc-flash hazards, OSHA 29 CFR1910.132(d)(1) requires employers to evaluate the workplace for hazards. And based on these assessments, the employer must select and require the use of appropriate personal protective equipment (PPE) for its employees.
NFPA 70E-2004 requires a flash hazard analysis be
performed in order to determine the Flash Protection Boundary and PPE required within that boundary.
Distance from arc source where potential
An skin exposure would normally result in
Within this boundary protective clothing
Working Distance – The distance between arc
source and the worker’s face or chest.
Approach Boundary - The approach working
distance for a qualified personnel.
Limited Approach Boundary – An approach limit
at a distance from an exposed live part within which a shock hazard exists.
Restricted Approach Boundary – An approach
boundary limit at a distance from an exposed live part within which there is an increased risk
with inadvertent movement, for personnel working in close proximity to the live part.
Prohibited Approach Boundary – An approach
limit at a distance from an exposed live part within which work is considered the same as making contact with the live part.
Rubber Glove Class Color Maximum Usage 00 Beige, Red 500 VAC
Red or 1,000 VAC Blue 1 White 7,500 VAC 2 Yellow 17,000 VAC 3 Green 26,500 VAC 4 Orange 36,000 VAC Leather Protector Grove - Always worn over rubber glove to provide needed mechanical protection against cuts, abrasions and punctures and alone do not provide any protection from electrical shock.
MOM Policy is to have Arc Flash Protection
Equations used are based on test performed in
laboratory and may differ at the facility in question.
Equations based on range of test values which
should be cross-reference to the facility’s electrical system parameters.
Random nature of arcs make it difficult to model
equations are “average” values.
NFPA 70E method is believed to be generally
conservative.
IEEE 1584 method is more realistic and aims to
avoid accidents due to limitations provided by
also lead to the restriction of visibility and movement, discomfort and reduces worker productivity.
Determine the incident energy for each
Determine the level of PPE required when
Determine labeling requirements Comply with OSHA regulations through
Identification of locations/equipment Collecting Data Short Circuit Analysis Protective Device Coordination Actual Arc Flash Analysis Arcing Current Arcing Times Determine Incident Energy Determine Flash Protection Boundary Determine Personal Protective Equipment (PPE) Category Documentation
Additions or deletions to a electrical
CHANGE THE SYSTEM AND YOU MUST