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Frequently
Asked
Questions
FAQAnswers from
Arc flashPhone: 503 655-5059Fax: 503
[email protected]
Q.
Q.
What are some of
the causes of anelectrical arc flash?
What are the
hazards from an arcflash?
Accidents, such as droppedtools, accidental contact
withelectrical systems and the buildup of conductive dust,
dirt,corrosion and particles.
Electrical Equipment andInsulation Failure
Improperly designed or utilizedequipment
Improper work procedures
An arc is produced by flow ofelectrical current throughionized
air after an initialflashover or short circuit.
Arcing faults release dangerouslevels of radiant heat
energy,capable of causing severe
burns. Fatal burns can occur upto five feet from the arc,
withsevere burns up to ten feet
away. Arcs produce some ofthe highest temperatures knownto occur
on earth; up to 35,000degrees Fahrenheit.
Clothing can be ignited severalfeet away. Blast shrapnel can
be distributed over a wide area.
This is 4times the surface temperatureof the sun.
Arcs spray droplets of moltenmetal with the
explosiondistributing the molten metal
produced by the arc over a largearea.
The vaporization of metal andheating of the air produces
blast
pressure waves that have thrownworkers across rooms andknocked
them off ladders.
Hearing loss from sound blast
Cost of treatment can exceed$1,000,000/case.
Potential Litigation fees
Potential Loss of Process
Potential Fines:Escalation of Insurance.
Q. What is the impactof an arc flash?
Treatment can require years ofskin grafting and
rehabilitation
Victim may never return towork or regain quality of life.
Victim may DIE.
Q
Q.
. What is the potentialexposure to an arcflash?
What is the
electrical industry doingto address the arc flashIssue?
Bureau of Labor Statistics datafor 1994 show 11,153 cases
ofreported days away from workdue to electrical
burns,electrocution/electrical shockinjuries, fires and
explosions.
The Census of Fatal Injuriesnoted 548 employees died fromthe
causes of electrical currentexposure, fires and explosions outof
6,588 work related fatalitiesnationwide.
In the US Chemical Industry,56% of the fatalities that
occurredover a 5-year period were
attributable to burns, fires andexplosions, with many of
theignition sources being related toelectrical activity.
Historically, the NationalElectrical Code (NEC) and othersafety
codes have been primarilyconcerned with protection fromfire,
electrocution, and shockhazard. Arc flash hazards werenot
addressed.
This is changing. The 2002 NECcontains requirements for
warning
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FAQ
labels and the National FireProtection Association (NFPA)70E and
Institute of Electricaland Electronics Engineers(IEEE) 1584,
provide guidanceon implementing appropriate
safety procedures.
NEC Article 110.16 requiresfield markingof potential arcflash
hazard for panels likely to
be serviced or examined inenergized condition. Thisarticle also
contains a FinePrint Note (FPN) regarding
proper signage and an FPNreferencing NFPA 70E. TheseFPNs are not
technically part of
the NEC.
OSHA has NOT specificallyaddressed Arc Flash, howeverexisting
and new provisionsimpact how it is addressed:
OSHA 1910.132(d), and1926.28(a). The employer isresponsible to
assess thehazards in the work place,
select, have, and use the correctPersonal Protective
Equipment(PPE) and document theassessment.
OSHA has tasked the NFPAwith addressing both shock andarc flash
hazards in detail forOSHA adoption (discussionsPCIC 2003).
Q. What Does NFPA-70E do to address arcflash hazards?
It defines a series ofrelated to electrical
safety when working onenergized equipment:
may be based on, available
and.
boundaries
Determining Flash ProtectionBoundariesvoltage
short-circuitcurrent predicted faultduration
Flash Protection BoundaryLimited Approach Boundary
BoundaryBoundary
Restricted ApproachProhibited Approach
NFPA 70E provides THREEacceptable methods of
determining flash protectionBoundary:
1. Simplified Table 220.2(B)(2),220.6(B) (9)
2. Analysis based on NFPA70E Annex B
3. Analysis based onIEEE-1584 Standards
Landmark agreementforged between OSHA,
IBEW and NECAcontractors to use
NFPA-70E to protectelectricians in Columbus,Ohio could set trend
for
the Nation.
Category Energy Level Typical Personal Protective Equipment
required (NFPA-70E)
1 4 cal/cm Fire Resistant (FR) shirt and FR pants
2 8 cal/cm FR shirt, FR pants, cotton underwear3 25 cal/cm Two
layers FR clothing, cotton underwear
4 40 cal/cm FR shirt, FR pants, multilayer flash suit,
cotton underwear
2
2
2
2
Other:
Face Protection Face Shield and/or safety glasses
Hand Protection Leather over rubber for arc flash protection
Leather work boots above 4 cal/cm2
Q. Are theredifferences betweenNFPA 70E and IEEE1584
calculations?
Both calculation methodsattempt to compute the expectedarc flash
energy that would becreated by an arcing fault. This isa worst-case
calculation based onexpected fault current, arc lengthand fault
duration.
Differences do exist between the
two calculation methods. It issuggested that you review
bothmethods to help determine theapproach that is appropriate
foryour facility.
NFPA-70E 2004 Equipment Requirements (Proposed)
Q. Are there
advantages of doingdetailed arc flashcalculations withEasyPower
software?
Recently, the PCIC safetyCommittee recommendedthat Arc Flash
Calculations becompleted in conjunction withShort Circuit
Calculations and
0 2 cal/cm Non-melting flammable materials
