Procedure for IEEE 1584 based arc flash calculations.Normalized
incident energy can be found using the equation below:lg En = K1 +
K2 + 1.!1 " lg#a + .11 " $ (1) En % incident energy &'cm2
normalized for time and distance. (he equation abo)e is based on
data normalized for a distance from the *ossible arc *oint to the
*erson of +1 mm. and an arcing time of .2 sec.K1 = %.,-2 for o*en
configurations. and is %./// for bo0 configurations ' enclosed
equi*ment.K2 =for ungrounded and high resistance grounded systems.
and equals %.111 for grounded systems.$ % ga* between conductors in
millimeters.#a % *redicted three *hase arcing current in 23. #t is
found by using formula 2 a4 or b4 so the o*erating time for
*rotecti)e de)ices can be determined. 5or 16 and lower systems:lg#a
= K + .++2 " lg #bf + .-++ " 6 + ./2+ " $ + .//!! " 6 " lg#bf % .17
" $" lg#bf (2a) lg % is logarithm base 1 8log14.#a % arcing current
in 23.En % normalized incident energy in &'cm2 as calculated by
(1).K % equals %.1/1 for o*en configurations. and %.-, for bo0
configurations.#bf % bolted fault current for three *hase faults in
23 symmetrical rms.6 % system )oltage in 26.$ % ga* between
condactors in millimeters. 9ol)e lg#a = .72 + .-!1 " lg #bf (2b)
for a**lications with a system )oltage ranging from 1 u* to 1/26.
#ncident energy can be found using the equation below:E = 7.1!7 "
:f " En " 8t ' .24 " 8+10';04 (3) E % incident energy e0*osure in
&'cm2.:f % calculation factor equal to 1. for )oltages abo)e 1
26. and 1./ for )oltages below 126.En % normalized incident energy
in &'cm2 as calculated by (1) abo)e.t % arcing time in
seconds.; % distance from *ossible arcing *oint to the *erson in
millimeters.0 % distance e0*onent. 5or cases where )oltage is o)er
1/ 26. or ga* is outside the range of the model. the theoretically
deri)ed 7.1!7 " :f " En " 8t ' .24 " 8+10'E=4?1'0 (5) 5or the 2.172
" 1+ " 6 " #bf " 8t ' E=4?1'2(6) ;= % distance of the boundary from
the arc *oint in millimeters.:f % calculation factor equal to 1.
for )oltages abo)e 1 26. and 1./ for )oltages below 126.En %
normalized incident energy in &'cm2 as calculated by (1).E= %
incident energy in &'cm2 at the boundary distance.#bf % bolted
fault current for three *hase faults in 23 symmetrical rms.t %
arcing time in seconds.0 % distance e0*onent.#bf % bolted fault
current E= is usualy set at / &'cm2 81.2 cal'cm2 4 for bare
s2in. or at the rating of *ro*osed *ersonal *rotection equi*ment.
Arc Flash TerminologyIncident Energy Exosure (his is the amount of
thermal incident energy to which the wor2er@s face and chest could
be e0*osed at wor2ing distance during an electrical arc e)ent.
#ncident energy is measured in Aoules *er centimeter squared
8&'cm24 or calories *er centimeter squared 8cal'cm24. Minimum
reported incident energy is 0.25 cal/cm2 wic is te accuracy limit
o! te test e"uipment. Incident Energy at Arc Flash !oundary 3 )alue
in cal'cmB2 to determine arc flash boundary 835=4 distance at that
#ncident Energy. (he #ncident Energy of 1.2 cal'cmB2 for bare s"in
is used in sol)ing equation for arc flash boundary in #EEE 1/!7
#uide !or $er!orming %rc &las 'a(ard )alculations. Cowe)er. the
$uide equation for arc flash boundary can be sol)ed with other
incident energy le)els as well such as the rating of *ro*osed
*ersonal *rotecti)e equi*ment 8DDE4. (he #ncident Energy at 3rc
5lash =oundary )alue should be equal or abo)e incident energy to
second degree burn for bare s2in e0*osure. Arc Flash !oundary (he
arc flash boundary is an a**roach limit at a distance from e0*osed
li)e *arts or enclosed li)e *arts if o*eration. mani*ulation. or
testing of equi*ment creates a *otential flash hazard. within which
a *erson could recei)e a second degree burn if an electrical arc
flash were to occur. 3 wor2er entering the arc flash boundary must
be qualified and must be wearing a**ro*riate DDE. (he arc flash
boundary is required to be calculated by N5D3 ,E. #a$ard %e&el
(his is the minimum le)el of Dersonal Drotecti)e Equi*ment in
calories *er centimeter squared. as e)aluated in #EEE 9tandard
1/!7. with the intent to *rotect the wor2er fromthe thermal effects
of the arc !las at wor2ing distance from the source of the arc. 'in
IncidentEnergy( cal)cm*+'ax IncidentEnergy( cal)cm*+#a$ard
%e&el,e-uired 'in,ating of PPE(cal)cm*+ Eb Eb + .1 7 1 77.1 ! 2
!!.1 2/ 1 2/2/.1 7 7 77.1 and abo)e :onsult Not 3)ailable
,ecommended Personal Protecti&e E-uiment . PPE
/#a$ard%e&elPersonal Protecti&e E-uiment . PPE /
Entreated natural fiber long slee)e shirt F *ants with a fabric
weight of at least 7./ oz'ydB2. safety glasses. ear canal inserts.
hea)y duty leather glo)es.13rc rated 83G4 shirt and 3G *ants or 3G
co)erall. 3G face shield. 3G Aac2et. safety glasses. hard hat. ear
canal inserts. hea)y duty leather glo)es. leather footwear.23rc
rated 83G4 shirt and 3G *ants or 3G co)erall. 3G flash suit hood.
3G Aac2et. safety glasses. hard hat. ear canal inserts. hea)y duty
leather glo)es. leather footwear.13rc rated 83G4 co)erall o)er 3G
shirt and 3G *ants. 3G flash suit. 3G hood. safety glasses. hard
hat. ear canal inserts. 3G glo)es. leather footwear.7Hultilayer arc
rated 83G4 flash suit o)er 3G co)erall o)er 3G shirt and 3G *ants.
3G flash suit hood. safety glasses. hard hat. ear canal inserts. 3G
glo)es. leather wor2 shoes. E-uiment 0lass :lasses of equi*ment
included in #EEE 1/!7 and ty*ical bus ga*s are shown in table
below: 0lasses of e-uiment Tyical bus gas( mmI*en 3ir 1 % 7
