FRED# 296
TD00301003E
MOLDED CASE CIRCUIT BREAKER
APPLICATION ON GROUNDED
B-PHASE SYSTEMS
Occasionally you may have an application that is a delta voltage source with a grounded
“B” phase, also known as corner grounded. Eaton Corporation literature states “for all 3
phase delta grounded B phase applications, refer to Eaton Corporation.” Following are
sketches of what the voltage source looks like with a breaker applied.
Std. 2 Pole Breaker (Fig 1) 2 or 3 Pole breaker with
Unprotected Ground Phase.
Protected
Single
Phase
Load
(Fig 2)
2 Phases
Protected
3 Phase
Load
Std 3 Pole Breaker (Fig 3) Std 3 Pole Breaker (Fig 4)
Protected
Single
Phase
Load
(Use outside poles when 2 poles of a 3 pole breaker are used)
Sizing a breaker for application in a Grounded B-Phase Delta system is different from
sizing a breaker for application in a solidly grounded or low-resistance grounded wye
system because the phase to ground interrupting duty requirement of an individual
breaker pole is different for each case.
A) In a grounded B-Phase System case, a single-line-to-ground fault occurring
downstream of the breaker must be interrupted by a single pole of the breaker
with full line-to-line voltage across that single interrupting pole.
B) In a neutral-grounded wye system, solidly-grounded or low-resistance
grounded; a downstream single-line-to-ground fault must likewise be
interrupted by a single pole of the breaker, but in this case with only line-toneutral voltage across that single interrupting pole.
This is the difference which determines the values of the following application data table:
Protected
3 Phase
Load
1 6/22/2009
PHASE TO GROUND INTERRUPTING RATINGS
MOLDED CASE CIRCUIT BREAKERS IN GROUNDED B-PHASE SYSTEMS
INTERRUPTION RATING,
CLASSIC
EB 5
EHB 18 10
FB 18 10 8.6
HFB 65 10 8.6
CA, CAH, HCA * 10
JA, KA 25 15 10
HKA 65 15 10
JB, KB, HKB 18 10
LB, LBB, HLB 25 10
DA 25
LA, LAB, HLA 400A 42 15 10
LA, LAB, HLA 600A 30 10 8.6
LC, HLC 30 10 8.6
LCL 65
MA, HMA 42 12 10
MA, HMA W/CERAMIC ARC
CHUTES
MC, HMC 42 12 10
NB, HNB 25 12
NB TRI-PAC 75
NC, HNC 25 12
PB, PC 65 25 20
PB TRI-PAC 100
Series C
GHB, GHC 14
GD 22 8.6
ED, EDH, EDC 10
EHD 14 10
FDB 14 10 10
FD, JD, JDB, KD,LD, LDB, CLD 35 10 10
HFD, HJD, HKD, HLD, CHLD 65 10 10
FDC, JDC, KDC, LDC, CLDC 100 10 10
MDL, CMDL 50 10 10
HMDL, CHMDL 65 10 10
ND, CND 50 14 14
HND, CHND 65 14 14
NDC, CNDC 100 14 14
NDU 150 14 14
240 VAC
42 15 10
kA
480
VAC
600
VAC
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PHASE TO GROUND INTERRUPTING RATINGS (Continued)
MOLDED CASE CIRCUIT BREAKERS IN GROUNDED B-PHASE SYSTEMS
INTERRUPTION RATING,
240
RD, CRD 1600, 2000 65 14 14
RDC, CRDC 1600, 2000 100 14 14
RD 2500 65 20 20
RDC 2500 100 20 20
Series G
EGB 18 10
EGE 25 10
EGS 35 10
EGH 65 10
EGC 100 10
JGE 25 10 10
JGS, LGE 35 10 10
LGS 50 10 10
JGH, LGH 65 10 10
JGC, LGC 100 10 10
JGU, LGU 150 10 10
JGX, LGX 200 10 10
NGS 800,1200 50 14 14
NGH 800,1200 65 14 14
NGC 800,1200 100 14 14
NGU 800 150 14 14
RGH 1600, 2000 65 14 14
RGC 1600, 2000 100 14 14
RGH 2500 65 20 20
RGC 2500 100 20 20
VAC
kA
480
VAC
600
VAC
• These breakers are U.L. listed for 240 VAC corner grounded applications. All others are Eaton
Corporation certified, but based on U.L. test requirements.
3 pole breakers may be used for 3 phase loads with the grounded phase connected through a breaker
pole. See Figure 4. In this configuration, the standard interruption values apply for phase to phase
interruption, but the reduced values apply for phase-to-ground interruption.
3 pole breakers may be also be used for single phase loads connected through the outside poles. –See
Figure 3.
Where permitted by the electrical code, 2 or 3 pole breakers may be used in the unprotected neutral
configuration, Figure 2. In this configuration, the reduced interruption values apply for all
interruptions
.
3 6/22/2009
The following corner grounded delta application ratings are Eaton Corporation certified,
but based on U.L. test requirements. Those interruption ratings are applicable to all
breakers not stated on the previous table.
CORNER GROUNDED CIRCUIT BREAKER I.C. RATING
DELTA SYSTEM VOLTS AMPERE RATING (AMPERES)
-------------------------------- ------------------------ ---------------240 with 240V Breaker 100 AND BELOW 4,330 FOR 240V
RATED BREAKER
240 with 240V Breaker 101-800 8,660 FOR 240V
RATED BREAKER
240 with 480V or 600V Breaker ALL USE 480V MARKED
480 OR 600 800 AND BELOW 8,660
480 OR 600 801-1200 12,120
480 OR 600 1201-2000 14,000
480 OR 600 2001-2500 20,000
480 OR 600 2501-3000 25,000
480 OR 600 3001-4000 30,000
All 480VAC or 600VAC rated breakers are suit a bl e fo r use on 24 0 VAC corner grounded delta
systems, but the short circuit rating must be reduced to the 480VAC short circuit current rating
marked on the breaker.
No 120/240VAC circuit breakers may be used on any corner grounded delta system.
3 pole breakers may be used for 3 phase loads with grounded phase connected through a breaker
pole. –See Figure 4.
3 pole breakers may also be used for single phase loads which will be connected through the
outside poles. See Figure 4. In this configuration, the standard interruption values apply for phase
to phase interruption, but the reduced values apply for phase-to-ground interruption.
Where permitted by the electrical code, 2 or 3 pole breakers may be used in the unprotected
neutral configuration, Figure 2. In this configuration, the reduced interruption values apply for all
interruptions.
Panel boards must be built as 3 phase 3 wire.
Series ratings do not apply for phase-to-gr ou nd inte r ru pt ion or for protected phase-to-unprotected
phase interruption.
RATING ON BREAKER
The protected phase-to-protected phase interruption values are not affected by the corner
grounded configuration.
Notice – Positive identification of the grounded phase through the entire system must be
made per the NEC Code.
4 6/22/2009
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