Motor Circuit Protection Tables

Motor Circuit Protection Tables
NEC® Article 430 and Tables Explanation
Columns 1 & 2
Motor horsepower ratings are listed in Column 1. Full load amps from Tables
430.247 through 430.250 are provided in Column 2.
Column 3
Various fuse types are listed in Column 3. The LPJ_SP is a 600Vac, 0 - 600 amp,
time-delay, Class J, “Low-Peak fuse, with a 300,000 amp interrupting rating. The
TCF is a 600Vac, 1 - 100 amp dual-element, time-delay, IP-20 finger-safe fuse with
Class J performance. The LP-CC is a 600Vac, 0 - 30 amp, time-delay, Class CC,
Low-Peak fuse with a 200,000 amp interrupting rating. The LPS-RK_SP and LPNRK_SP are 600 and 250Vac, 0 - 600 amp, time-delay, Class RK1, Low-Peak fuses
with interrupting ratings of 300,000 amps. FRS-R and FRN-R are 600 and 250Vac,
0 - 600 amp, time-delay, Class RK5, Fusetron Dual-Element fuses with interrupting
ratings of 200,000 amps. The KRP-C_SP is a 600Vac, 601 - 6000 amp, time-delay,
Class L, Low-Peak fuse, with a 300,000 amp AC interrupting rating. The DC listed
ratings for these fuses are:
LPJ
TCF
LP-CC
LP-CC
LP-CC
1 to 600SP
1 to 100
1
⁄2 to 2 8⁄10
3 to 15
20 to 30
300Vdc
300Vdc
300Vdc
150Vdc
300Vdc
LPN-RK
LPN-RK
LPS-RK
FRN-R
FRS-R
0 to 60SP
70 to 600SP
0 to 600SP
0 to 600
0 to 600
125Vdc
250Vdc
300Vdc
125Vdc
300Vdc
Column 4 - Optimal Branch Circuit Protection
There are two distinct levels of protection philosophy provided in this Column. LPSRK_SP, LPN-RK_SP, FRS-R and FRN-R fuses are sized for motor running
“back-up” protection and provide superb short circuit protection at the same time.
LPJ_SP, TCF, and LP-CC fuses are sized a little larger but are even more current
limiting, providing an even greater degree of short circuit protection for the motor
circuit.
All the fuses selected from this column provide short circuit and ground-fault protection for motor branch circuits (430.52), but typically are not the maximum
allowed. Fuses sized in accordance with Column 4 must be used in conjunction
with properly sized motor overload protection such as overload relays or solid state
motor controllers (430.32). This fuse sizing is normally large enough to allow the
overload protective device to operate on overloads without opening the fuse. Yet
for many cases, this fuse amp rating selection is smaller than the maximums
allowed per Columns 5 or 6 (430.52). In some cases, this smaller amp rating
selection may provide the benefits of a smaller size disconnect and better short circuit protection. If a motor has a long starting time, high starting current profile or is
cycled frequently, it may be necessary to use Column 5 or 6.
The LPS-RK_SP, LPN-RK_SP, FRS-R and FRN-R fuses sized per this column provide short circuit and ground-fault protection for motor branch circuits (430.52) as
discussed in the previous paragraph. In addition, these dual-element fuses exhibit
longer time-delay characteristics and can therefore be sized to provide back-up
motor overload protection. The fuse sizing in Column 4 for LPS-RK_SP, LPNRK_SP, FRS-R and FRN-R fuses provides a degree of motor and circuit overload
protection to back-up the normal motor overload protective device. Note: This level
of protection requires a well-designed, true dual-element fuse. The Fusetron
Fuses, FRS-R and FRN-R, and Low-Peak Fuses, LPS-RK_SP and LPN-RK_SP,
are the industry leading dual-element fuses with excellent over-load time-delay
characteristics and current-limiting short circuit ability. The Low-Peak Dual-Element
Fuses have better current-limiting ability than Fusetron Dual-Element Fuses.
The amp ratings in Column 4 are determined by using Column 2 motor ampacity
values and the following:
LPJ_SP & TCF: 150% or the next larger Cooper Bussmann amp rating if 150% does
not correspond to a Cooper Bussmann fuse amp rating.
LP-CC 1⁄2 to 15A: 200% (150% for DC) or the next larger Cooper Bussmann size if
200% (150% for DC) does not correspond to a Cooper Bussmann fuse amp
rating.
©2005 Cooper Bussmann
LP-CC 20 to 30A: 300% (150% for DC) or the next larger Cooper Bussmann size if
300% (150% for DC) does not correspond to a Cooper Bussmann fuse amp
rating.
LPS-RK_SP and LPN-RK_SP: 130% or the next larger Cooper Bussmann amp rating if 130% does not correspond to a Cooper Bussmann fuse amp rating.
FRS-R and FRN-R: 125% or the next larger Cooper Bussmann amp rating if 125%
does not correspond to a Cooper Bussmann fuse amp rating.
Column 5 - Branch Circuit Protection, Max. General
Applications
Fuses selected from this column are intended to provide short circuit and groundfault protection for motor branch circuits. Fuses sized in accordance with Column 5
must be used in conjunction with properly sized motor overload protection such as
overload relays or solid state motor controllers (430.32). Column 5 fuse sizing
provides the maximum NEC® Table 430.52 amp ratings for general purpose
applications. It takes into account 430.52(C)(1) Exception No. 1, which allows the
next standard amp rating fuse (per standard fuse amp ratings in 240.6) to be used
if the maximum percentage in Table 430.52 does not correspond to a standard fuse
amp rating. If this Column 5 fuse sizing does not allow the motor to start, then
Column 6 may provide a larger amp rating.
The amp ratings in Column 5 are deter-mined by using Column 2 motor ampacity
values and the following:
LPJ_SP, TCF, LPS-RK_SP, LPN-RK_SP, FRS-R, FRN-R and KRP-C_SP: 175%
(150% for DC motors) or the next larger 240.6 standard fuse amp rating if 175%
(150% for DC motors) does not correspond to a standard fuse amp rating.
LP-CC: 300% (150% for DC motors) or the next larger 240.6 standard fuse amp
rating if 300% (150% for DC motors) does not correspond to a standard fuse amp
rating.
Sizes shown for the LP-CC can also be used for non-time delay fuses such as JKS,
KTN-R, KTS-R, JJN, JJS, and KTK-R.
Column 6 - Branch Circuit Protection, Max. Heavy Start
When the amp rating shown in Column 5 is not sufficient to start a motor, a larger
amp rating is often available by utilizing 430.52(C)(1) Exception No. 2. The amp
ratings in Column 6 are the larger of the amp rating allowed by 430.52(C)(1)
Exception No. 1, or 430.52(C)(1) Exception No. 2. These amp ratings will often be
required when acceleration times are greater than 5 seconds, when plugging or
jogging applications exist, or where there are high inrush currents (such as Design
E or energy efficient Design B motors). (In a few cases, the amp rating in Column 6
may be smaller than the maximum permitted due to the limitation of the fuse type,
such as LP-CC, Class CC fuses that are only available in ratings up to 30 amps. In
these cases, if the amp rating shown is not sufficient to start the motor, select a different family of fuses that meet the requirements.) The amp ratings in Column 6
are determined by using Column 2 motor ampacity values and the following:
LPJ_SP, TCF, LPS-RK_SP, LPN-RK_SP, FRS-R, and FRN-R: 225% or the next
smaller Cooper Bussmann amp rating if 225% does not correspond to a Cooper
Bussmann fuse amp rating.
LP-CC: 400% or the next smaller Cooper Bussmann amp rating if 400% does not correspond to a Cooper Bussmann fuse amp rating.
KRP-C_SP: 300% or the next smaller Cooper Bussmann amp rating, if 300% does
not correspond to a Cooper Bussmann amp rating.
Sizes shown for the LP-CC can also be used for non-time delay fuses such as
JKS, KTN-R, KTS-R, JJN, JJS, AND KTK-R.
Column 7
Horsepower-rated switch sizes given in Column 7 are based on 115% (430.110) of
Column 2. Switch sizes need to be increased when, because of starting requirements, the fuses are sized above the rating of the switch shown in this column.
Column 8
Sizes listed are for general-purpose magnetic controllers (single speed, fullvolt-age for limited plugging and jogging-duty) as shown in NEMA Standards
Publication ICS-2-2000.
145
Motor Circuit Protection Tables
NEC® Article 430 and Tables Explanation
Column 9
Column 10
Copper wire sizes are based upon 125% (430.22) of values shown in Column 2
and ampacities listed in Table 310.16 for 75°C terminals. Although the NEC®
allows 60°C terminations for equipment rated 100 amp or less, most
equipment terminations have been rated for 75°C conductors. If equipment terminations are rated for 60°C conductors only, the 60°C ampacities must be utilized
and therefore larger conductor sizes may be required than those shown in this column. See 110.14(C) (1)(a)(4).
These rigid metallic conduit sizes are based upon copper conductors with THWN
or THHN insulation, Table C8 of Annex C, and 75°C equipment terminals.
200Vac Three-Phase Motors & Circuits
1
Motor
Size
Table
430.250
HP
2
Motor
FLA
Table
430.250
AMPS
⁄2
2.5
3
⁄4
3.7
1
4.8
1 1⁄2
6.9
2
7.8
3
11
5
17.5
7 1⁄2
25.3
10
32.2
15
48.3
20
62.1
1
3
Fuse
4
Optimal
Branch Ckt
Protection
Type
Class
LPJ_SP
TCF
LP-CC
LPN-RK_SP
FRN-R
LPJ_SP
TCF
LP-CC
LPN-RK_SP
FRN-R
LPJ_SP
TCF
LP-CC
LPN-RK_SP
FRN-R
LPJ_SP
TCF
LP-CC
LPN-RK_SP
FRN-R
LPJ_SP
TCF
LP-CC
LPN-RK_SP
FRN-R
LPJ_SP
TCF
LP-CC
LPN-RK_SP
FRN-R
LPJ_SP
TCF
LPN-RK_SP
FRN-R
LPJ_SP
TCF
LPN-RK_SP
FRN-R
LPJ_SP
TCF
LPN-RK_SP
FRN-R
LPJ_SP
TCF
LPN-RK_SP
FRN-R
LPJ_SP
TCF
LPN-RK_SP
FRN-R
J
Jƒ
CC
RK1
RK5
J
Jƒ
CC
RK1
RK5
J
Jƒ
CC
RK1
RK5
J
Jƒ
CC
RK1
RK5
J
Jƒ
CC
RK1
RK5
J
Jƒ
CC
RK1
RK5
J
Jƒ
RK1
RK5
J
Jƒ
RK1
RK5
J
Jƒ
RK1
RK5
J
Jƒ
RK1
RK5
J
Jƒ
RK1
RK5
AMPS1
4
6
5
3 1⁄2
3 2⁄10
5 6⁄10
6
7 1⁄2
5
5
8
10
10
6 1⁄4
6
12
15
15
9
9
12
15
25
12
10
17 1⁄2
17 1⁄2
25
15
15
30
30
25
25
40
40
35
35
50
50
45
45
80
80
70
70
100
100
90
80
5
NEC®
Max for
Gen. Applic
430.52(C)(1)
Exc. No. 1
AMPS1
6
6
10
6
6
10
10
15
10
10
10
10
15
10
10
15
15
25
15
15
15
15
25
15
15
20
20
–
20
20
35
35
35
35
45
45
45
45
60
60
60
60
90
90
90
90
110
–
110
110
Conduit sizes are for three conductors per circuit for three phase motors and two
conductors per circuit for single phase and DC motors. Conduit sizes may need to
be increased if equipment grounding conductors or neutrals are also installed in
the conduit.
If equipment terminations are rated for 60°C conductors only, the 60°C ampacities
must be utilized and therefore larger conductor sizes and conduit sizes may be
required.
Conductors operated in a high ambient temperature may need to be derated.
(See correction factor table at the bottom of Table 310.16.)
6
NEC® Max
for Heavy
Start
430.52(C)(1)
Exc. No. 2
AMPS1
6
6
10
6
6
10
10
15
10
10
10
10
15
10
10
15
15
25
15
15
17 1⁄2
17 1⁄2
30
17 1⁄2
17 1⁄2
20
20
–
20
20
35
35
35
35
50
50
50
50
70
–
70
70
100
100
100
100
125
–
125
125
7
Minimum
Switch
Size
430.110
AMPS
8
Minimum
NEMA
Starter
NEMA ICS 22000
Size
9
Minimum
Copper Wire
THWN or THHN AWG
or KCMIL
Table 310.16
Size
10
Minimum
Rigid Metallic
Conduit
Annex C
Table C8
Inches
30
00
14
1
30
00
14
1
30
00
14
1
30
00
14
1
30
0
14
1
30
0
14
1
30*
1
12
1
60
1
10**
1
60*
2
8**
1
100
3
6**
3
100*
3
4**
⁄2
⁄2
⁄2
⁄2
⁄2
⁄2
⁄2
⁄2**
⁄2**
⁄4**
1
* Switch size must be increased if the amp rating of the fuse exceeds the amp rating of the switch.
1 Per 430.52(C)(2), if the motor controller manufacturer’s overload relay tables state a maximum branch circuit protective device of a lower rating, that lower rating must be used in lieu of the sizes shown in Columns 4, 5, or 6.
** If equipment terminations are rated for 60°C conductors only, the 60°C conductor ampacities must be utilized and therefore larger conductor sizes or conduit sizes may be required.
ƒ
Class J performance, special finger-safe dimensions.
146
©2005 Cooper Bussmann
Motor Circuit Protection Tables
200Vac Three-Phase Motors & Circuits continued
1
Motor
Size
Table
430.250
HP
2
Motor
FLA
Table
430.250
AMPS
25
78.2
30
92
40
120
50
150
60
177
75
221
100
285
125
359
150
414
200
552
*
1
**
2
3
Fuse
4
Optimal
Branch Ckt
Protection
Type
Class
LPJ_SP
LPN-RK_SP
FRN-R
LPJ_SP
LPN-RK_SP
FRN-R
LPJ_SP
LPN-RK_SP
FRN-R
LPJ_SP
LPN-RK_SP
FRN-R
LPJ_SP
LPN-RK_SP
FRN-R
LPJ_SP
LPN-RK_SP
FRN-R
KRP-C_SP
LPJ_SP
LPN-RK_SP
FRN-R
KRP-C_SP
LPJ_SP
LPN-RK_SP
FRN-R
KRP-C_SP
LPN-RK_SP
FRN-R
KRP-C_SP
KRP-C_SP
J
RK1
RK5
J
RK1
RK5
J
RK1
RK5
J
RK1
RK5
J
RK1
RK5
J
RK1
RK5
L
J
RK1
RK5
L
J
RK1
RK5
L
RK1
RK5
L
L
AMPS 1
125
110
100
150
125
125
200
175
150
225
200
200
300
250
225
350
300
300
–
450
400
400
–
600
500
450
–
600
600
–
–
5
NEC®
Max for
Gen. Applic
430.52(C)(1)
Exc. No. 1
AMPS 1
150
150
150
175
175
175
225
225
225
300
300
300
350
350
350
400
400
400
–
500
500
500
–
–
–
–
700
–
–
800
1000
6
NEC® Max
for Heavy
Start
430.52(C)(1)
Exc. No. 2
AMPS 1
175
175
175
200
200
200
250
250
250
300
300
300
350
350
350
450
450
450
650
600
600
600
800
–
–
–
1000
–
–
1200
1600
7
Minimum
Switch
Size
430.110
AMPS
8
Minimum
NEMA
Starter
NEMA ICS 22000
Size
9
Minimum
Copper Wire
THWN or THHN AWG
or KCMIL
Table 310.16
Size
10
Minimum
Rigid Metallic
Conduit
Annex C
Table C8
Inches
100*
3
3**
1**
200
4
2**
1**
200*
4
1/0
1 1⁄4
200*
5
3/0
1 1⁄2
400
5
4/0
2
400*
5
300
2
400*
6
500
3
600*
6
4/0 2/PHASE
(2)2
600*
6
300 2/PHASE
(2)2
1200
72
500 2/PHASE
(2)3
Switch size must be increased if the amp rating of the fuse exceeds the amp rating of the switch.
Per 430.52(C)(2), if the motor controller manufacturer’s overload relay tables state a maximum branch circuit protective device of a lower rating, that lower rating must be used in lieu of the sizes shown in Columns 4, 5, or 6.
If equipment terminations are rated for 60°C conductors only, the 60°C conductor ampacities must be utilized and therefore larger conductor sizes or conduit sizes may be required.
These sizes are typical. They are not shown in NEMA ICS 2-2000.
208Vac Three-Phase Motors & Circuits
1
Motor
Size
Table
430.250
HP
2
Motor
FLA
Table
430.250
AMPS
⁄2
2.4
3
⁄4
3.5
1
4.6
1 1⁄2
6.6
1
3
Fuse
4
Optimal
Branch Ckt
Protection
Type
Class
LPJ_SP
TCF
LP-CC
LPN-RK_SP
FRN-R
LPJ_SP
TCF
LP-CC
LPN-RK_SP
FRN-R
LPJ_SP
TCF
LP-CC
LPN-RK_SP
FRN-R
LPJ_SP
TCF
LP-CC
LPN-RK_SP
FRN-R
J
Jƒ
CC
RK1
RK5
J
Jƒ
CC
RK1
RK5
J
Jƒ
CC
RK1
RK5
J
Jƒ
CC
RK1
RK5
AMPS1
4
6
5
3 1⁄2
3
5 6⁄10
6
7
5
4 1⁄2
7
10
10
6
6
10
10
15
9
9
5
NEC®
Max for
Gen. Applic
430.52(C)(1)
Exc. No. 1
AMPS1
6
6
10
6
6
10
10
15
10
10
10
10
15
10
10
15
15
20
15
15
6
NEC® Max
for Heavy
Start
430.52(C)(1)
Exc. No. 2
AMPS1
6
6
10
6
6
10
10
15
10
10
10
10
15
10
10
15
15
25
15
15
7
Minimum
Switch
Size
430.110
AMPS
8
Minimum
NEMA
Starter
NEMA ICS 22000
Size2
9
Minimum
Copper Wire
THWN or THHN AWG
or KCMIL
Table 310.16
Size
10
Minimum
Rigid Metallic
Conduit
Annex C
Table C8
Inches
30
00
14
1
30
00
14
1
30
00
14
1
30
00
14
1
⁄2
⁄2
⁄2
⁄2
*Switch size must be increased if the amp rating of the fuse exceeds the amp rating of the switch.
1 Per 430.52(C)(2), if the motor controller manufacturer’s overload relay tables state a maximum branch circuit protective device of a lower rating, that lower rating must be used in lieu of the sizes shown in Columns 4, 5, or 6.
**If equipment terminations are rated for 60°C conductors only, the 60°C conductor ampacities must be utilized and therefore larger conductor sizes or conduit sizes may be required.
2 These sizes are typical. They are not shown in NEMA ICS 2-2000.
ƒ
Class J performance, special finger-safe dimensions.
©2005 Cooper Bussmann
147
Motor Circuit Protection Tables
208Vac Three-Phase Motors & Circuits continued
1
Motor
Size
Table
430.250
HP
2
Motor
FLA
Table
430.250
AMPS
2
7.5
3
10.6
5
16.7
7 1⁄2
24.2
10
30.8
15
46.2
20
59.4
25
74.8
30
88
40
114
50
143
60
169
75
211
100
273
125
343
150
396
200
528
3
Fuse
4
Optimal
Branch Ckt
Protection
Type
Class
LPJ_SP
TCF
LP-CC
LPN-RK_SP
FRN-R
LPJ_SP
TCF
LPN-RK_SP
FRN-R
LPJ_SP
TCF
LPN-RK_SP
FRN-R
LPJ_SP
TCF
LPN-RK_SP
FRN-R
LPJ_SP
TCF
LPN-RK_SP
FRN-R
LPJ_SP
TCF
LPN-RK_SP
FRN-R
LPJ_SP
TCF
LPN-RK_SP
FRN-R
LPJ_SP
LPN-RK_SP
FRN-R
LPJ_SP
LPN-RK_SP
FRN-R
LPJ_SP
LPN-RK_SP
FRN-R
LPJ_SP
LPN-RK_SP
FRN-R
LPJ_SP
LPN-RK_SP
FRN-R
LPJ_SP
LPN-RK_SP
FRN-R
KRP-C_SP
LPJ_SP
LPN-RK_SP
FRN-R
KRP-C_SP
LPJ_SP
LPN-RK_SP
FRN-R
KRP-C_SP
LPJ_SP
LPN-RK_SP
FRN-R
KRP-C_SP
KRP-C_SP
J
Jƒ
CC
RK1
RK5
J
Jƒ
RK1
RK5
J
Jƒ
RK1
RK5
J
Jƒ
RK1
RK5
J
Jƒ
RK1
RK5
J
Jƒ
RK1
RK5
J
Jƒ
RK1
RK5
J
RK1
RK5
J
RK1
RK5
J
RK1
RK5
J
RK1
RK5
J
RK1
RK5
J
RK1
RK5
L
J
RK1
RK5
L
J
RK1
RK5
L
J
RK1
RK5
L
L
AMPS1
12
15
15
10
10
17 1⁄2
17 1⁄2
15
15
30
30
25
25
40
40
35
35
50
50
45
40
70
70
70
60
90
90
80
80
125
100
100
150
125
110
175
150
150
225
200
200
300
225
225
350
300
300
–
450
400
350
–
600
450
450
–
600
600
500
–
–
5
NEC®
Max for
Gen. Applic
430.52(C)(1)
Exc. No. 1
AMPS1
15
15
25
15
15
20
20
20
20
30
30
30
30
45
45
45
45
60
60
60
60
90
90
90
90
110
–
110
110
150
150
150
175
175
175
200
200
200
300
300
300
300
300
300
400
400
400
–
500
500
500
–
–
–
–
601
–
–
–
700
1000
6
NEC® Max
for Heavy
Start
430.52(C)(1)
Exc. No. 2
AMPS1
15
15
30
15
15
20
20
20
20
35
35
35
35
50
50
50
50
60
60
60
60
100
100
100
100
125
–
125
125
150
150
150
175
175
175
250
250
250
300
300
300
350
350
350
450
450
450
601
600
600
600
800
–
–
–
1000
–
–
–
1100
1500
7
Minimum
Switch
Size
430.110
AMPS
8
Minimum
NEMA
Starter
NEMA ICS 22000
Size2
9
Minimum
Copper Wire
THWN or THHN AWG
or KCMIL
Table 310.16
Size
10
Minimum
Rigid Metallic
Conduit
Annex C
Table C8
Inches
30
0
14
1
30
0
14
1
30*
1
12
1
60
1
10**
1
60
2
8
1
60*
3
6**
3
100*
3
4**
1
100*
3
3**
1**
200
4
2**
1**
200*
4
1/0
1 1⁄4
200*
5
3/0
1 1⁄2
400
5
4/0
2
400*
5
300
2
400*
6
500
3
600*
6
4/0 2/PHASE
(2)2
600*
6
250 2/PHASE
(2)2
1200*
7
400 2/PHASE
(2)2-2 1⁄2
⁄2
⁄2
⁄2
⁄2
⁄2**
⁄4**
*Switch size must be increased if the amp rating of the fuse exceeds the amp rating of the switch.
1 Per 430.52(C)(2), if the motor controller manufacturer’s overload relay tables state a maximum branch circuit protective device of a lower rating, that lower rating must be used in lieu of the sizes shown in Columns 4, 5, or 6.
**If equipment terminations are rated for 60°C conductors only, the 60°C conductor ampacities must be utilized and therefore larger conductor sizes or conduit sizes may be required.
2 These sizes are typical. They are not shown in NEMA ICS 2-2000.
ƒ
Class J performance, special finger-safe dimensions.
148
©2005 Cooper Bussmann
Motor Circuit Protection Tables
230Vac Three-Phase Motors & Circuits (220-240Vac Systems)
1
Motor
Size
Table
430.250
HP
2
Motor
FLA
Table
430.250
AMPS
⁄2
2.2
3
⁄4
3.2
1
4.2
1
1 1⁄2
6
2
6.8
3
9.6
5
15.2
7 1⁄2
22
10
28
15
42
20
54
25
68
30
80
40
104
50
130
60
154
3
Fuse
4
Optimal
Branch Ckt
Protection
Type
Class
LPJ_SP
TCF
LP-CC
LPN-RK_SP
FRN-R
LPJ_SP
TCF
LP-CC
LPN-RK_SP
FRN-R
LPJ_SP
TCF
LP-CC
LPN-RK_SP
FRN-R
LPJ_SP
TCF
LP-CC
LPN-RK_SP
FRN-R
LPJ_SP
TCF
LP-CC
LPN-RK_SP
FRN-R
LPJ_SP
TCF
LP-CC
LPN-RK_SP
FRN-R
LPJ_SP
TCF
LPN-RK_SP
FRN-R
LPJ_SP
TCF
LPN-RK_SP
FRN-R
LPJ_SP
TCF
LPN-RK_SP
FRN-R
LPJ_SP
TCF
LPN-RK_SP
FRN-R
LPJ_SP
TCF
LPN-RK_SP
FRN-R
LPJ_SP
LPN-RK_SP
FRN-R
LPJ_SP
LPN-RK_SP
FRN-R
LPJ_SP
LPN-RK_SP
FRN-R
LPJ_SP
LPN-RK_SP
FRN-R
LPJ_SP
LPN-RK_SP
FRN-R
J
Jƒ
CC
RK1
RK5
J
Jƒ
CC
RK1
RK5
J
Jƒ
CC
RK1
RK5
J
Jƒ
CC
RK1
RK5
J
Jƒ
CC
RK1
RK5
J
Jƒ
CC
RK1
RK5
J
Jƒ
RK1
RK5
J
Jƒ
RK1
RK5
J
Jƒ
RK1
RK5
J
Jƒ
RK1
RK5
J
Jƒ
RK1
RK5
J
RK1
RK5
J
RK1
RK5
J
RK1
RK5
J
RK1
RK5
J
RK1
RK5
AMPS1
3 1⁄2
6
4 1⁄2
3
2 8/10
5
6
7
4 1⁄2
4
7
10
9
5 6⁄10
5 8⁄10
9
10
12
8
7 1⁄2
12
15
15
9
9
15
15
30
15
12
25
25
20
20
35
34
30
30
45
45
40
35
70
70
60
60
90
90
80
70
110
90
90
125
110
100
175
150
150
200
175
175
250
225
200
5
NEC®
Max for
Gen. Applic
430.52(C)(1)
Exc. No. 1
AMPS1
6
6
10
6
6
6
6
10
6
6
10
10
15
10
10
15
15
20
15
15
15
15
25
15
15
20
20
30
20
20
30
30
30
30
40
40
40
40
50
50
50
50
80
80
80
80
100
100
100
100
125
125
125
150
150
150
200
200
200
250
250
250
300
300
300
6
NEC® Max
for Heavy
Start
430.52(C)(1)
Exc. No. 2
AMPS1
6
6
10
6
6
7
6
12
7
7
10
10
15
10
10
15
15
20
15
15
15
15
25
15
15
20
20
30
20
20
30
30
30
30
45
45
45
45
60
60
60
60
90
90
90
90
110
–
110
110
150
150
150
175
175
175
225
225
225
250
250
250
300
300
300
7
Minimum
Switch
Size
430.110
AMPS
8
Minimum
NEMA
Starter
NEMA ICS 22000
Size2
9
Minimum
Copper Wire
THWN or THHN AWG
or KCMIL
Table 310.16
Size
10
Minimum
Rigid Metallic
Conduit
Annex C
Table C8
Inches
30
00
14
1
30
00
14
1
30
00
14
1
30
00
14
1
30
0
14
1
30
0
14
1
30
1
14
1
30*
1
10
1
60
2
10**
1
60*
2
6
3
100*
3
4
1
100*
3
4**
1
100*
3
3**
1**
200*
4
1**
1 1⁄4**
200*
4
2/0
1 1⁄2
200*
5
3/0
1 1⁄2
⁄2
⁄2
⁄2
⁄2
⁄2
⁄2
⁄2
⁄2
⁄2
⁄4
*Switch size must be increased if the amp rating of the fuse exceeds the amp rating of the switch.
1 Per 430.52(C)(2), if the motor controller manufacturer’s overload relay tables state a maximum branch circuit protective device of a lower rating, that lower rating must be used in lieu of the sizes shown in Columns 4, 5, or 6.
**If equipment terminations are rated for 60°C conductors only, the 60°C conductor ampacities must be utilized and therefore larger conductor sizes or conduit sizes may be required.
2 These sizes are typical. They are not shown in NEMA ICS 2-2000.
ƒ
Class J performance, special finger-safe dimensions.
4 Limited by 600 amp being the largest amp rating for FRN-R and LPN-RK_SP.
©2005 Cooper Bussmann
149
Motor Circuit Protection Tables
230Vac Three-Phase Motors & Circuits (220-240Vac Systems) continued
1
Motor
Size
Table
430.250
HP
2
Motor
FLA
Table
430.250
AMPS
75
192
100
248
125
312
150
360
200
480
3
Fuse
4
Optimal
Branch Ckt
Protection
Type
Class
LPJ_SP
LPN-RK_SP
FRN-R
LPJ_SP
LPN-RK_SP
FRN-R
KRP-C_SP
LPJ_SP
LPN-RK_SP
FRN-R
KRP-C_SP
LPJ_SP
LPN-RK_SP
FRN-R
KRP-C_SP
FRN-R
KRP-C_SP
J
RK1
RK5
J
RK1
RK5
L
J
RK1
RK5
L
J
RK1
RK5
L
RK5
L
AMPS1
300
250
250
400
350
350
–
500
450
400
–
600
500
450
–
600
–
5
NEC®
Max for
Gen. Applic
430.52(C)(1)
Exc. No. 1
AMPS1
350
350
350
450
450
450
–
600
600
600
—
–
6004
6004
700
–
1000
6
NEC® Max
for Heavy
Start
430.52(C)(1)
Exc. No. 2
AMPS1
400
400
400
500
500
500
700
–
–
–
900
–
–
–
1000
–
1400
7
Minimum
Switch
Size
430.110
AMPS
8
Minimum
NEMA
Starter
NEMA ICS 22000
Size2
9
Minimum
Copper Wire
THWN or THHN AWG
or KCMIL
Table 310.16
Size
10
Minimum
Rigid Metallic
Conduit
Annex C
Table C8
Inches
400
5
250
2
400*
5
350
2 1⁄2
400*
6
3/0 2/PHASE
(2) 1 1⁄2
600*
6
4/0 2/PHASE
(2) 2
600*
6
350 2/PHASE
(2) 2-2 1⁄2
*Switch size must be increased if the amp rating of the fuse exceeds the amp rating of the switch.
1 Per 430.52(C)(2), if the motor controller manufacturer’s overload relay tables state a maximum branch circuit protective device of a lower rating, that lower rating must be used in lieu of the sizes shown in Columns 4, 5, or 6.
**If equipment terminations are rated for 60°C conductors only, the 60°C conductor ampacities must be utilized and therefore larger conductor sizes or conduit sizes may be required.
2 These sizes are typical. They are not shown in NEMA ICS 2-2000.
4 Limited by 600 amp being the largest amp rating for FRN-R and LPN-RK_SP.
460Vac Three-Phase Motors & Circuits (440-480Vac Systems)
1
Motor
Size
Table
430.250
HP
2
Motor
FLA
Table
430.250
AMPS
⁄2
1.1
3
⁄4
1.6
1
2.1
1
1 1⁄2
3
2
3.4
3
4.8
5
7.6
3
Fuse
4
Optimal
Branch Ckt
Protection
Type
Class
LPJ_SP
TCF
LP-CC
LPS-RK_SP
FRS-R
LPJ_SP
TCF
LP-CC
LPS-RK_SP
FRS-R
LPJ_SP
TCF
LP-CC
LPS-RK_SP
FRS-R
LPJ_SP
TCF
LP-CC
LPS-RK_SP
FRS-R
LPJ_SP
TCF
LP-CC
LPS-RK_SP
FRS-R
LPJ_SP
TCF
LP-CC
LPS-RK_SP
FRS-R
LPJ_SP
TCF
LP-CC
LPS-RK_SP
FRS-R
J
Jƒ
CC
RK1
RK5
J
Jƒ
CC
RK1
RK5
J
Jƒ
CC
RK1
RK5
J
Jƒ
CC
RK1
RK5
J
Jƒ
CC
RK1
RK5
J
Jƒ
CC
RK1
RK5
J
Jƒ
CC
RK1
RK5
AMPS1
1 8⁄10
3
2 1⁄4
1 11⁄2
1 4⁄10
2 1⁄2
3
3 2⁄10
2 1⁄4
2
3 2⁄10
6
4 1⁄2
2 8⁄10
2 8⁄10
4 1⁄2
6
6
4
4
5 6⁄10
6
71
4 1⁄2
4 1⁄2
8
10
10
6 1⁄4
6
12
15
25
10
10
5
NEC®
Max for
Gen. Applic
430.52(C)(1)
Exc. No. 1
AMPS1
3
3
6
3
3
3
3
6
3
3
6
6
10
6
6
6
6
10
6
6
6
6
5
6
6
10
10
15
10
10
15
15
25
15
15
6
NEC® Max
for Heavy
Start
430.52(C)(1)
Exc. No. 2
AMPS1
3
3
6
3
3
3 1⁄2
3
6 1⁄4
3 1⁄2
3 1⁄2
6
6
10
6
6
6
6
12
6 1⁄4
6 1⁄4
7
6
15
7
7 1⁄2
10
10
15
10
10
15
15
30
15
15
7
Minimum
Switch
Size
430.110
AMPS
8
Minimum
NEMA
Starter
NEMA ICS 22000
Size2
9
Minimum
Copper Wire
THWN or THHN AWG
or KCMIL
Table 310.16
Size
10
Minimum
Rigid Metallic
Conduit
Annex C
Table C8
Inches
30
00
14
1
30
00
14
1
30
00
14
1
30
00
14
1
30
00
14
1
30
0
14
1
30
0
14
1
⁄2
⁄2
⁄2
⁄2
⁄2
⁄2
⁄2
* Switch size must be increased if the amp rating of the fuse exceeds the amp rating of the switch.
1 Per 430.52(C)(2), if the motor controller manufacturer’s overload relay tables state a maximum branch circuit protective device of a lower rating, that lower rating must be used in lieu of the sizes shown in Columns 4, 5, or 6.
** If equipment terminations are rated for 60°C conductors only, the 60°C conductor ampacities must be utilized and therefore larger conductor sizes or conduit sizes may be required.
ƒ
Class J performance, special finger-safe dimensions.
150
©2005 Cooper Bussmann
Motor Circuit Protection Tables
460Vac Three-Phase Motors & Circuits (440-480Vac Systems) continued
1
Motor
Size
Table
430.250
HP
2
Motor
FLA
Table
430.250
AMPS
1
7 ⁄2
11
10
14
15
21
20
27
25
34
30
40
40
52
50
65
60
77
75
96
100
124
125
156
150
180
200
240
250
302
300
361
350
414
400
477
450
500
515
590
*
1
**
4
ƒ
3
Fuse
4
Optimal
Branch Ckt
Protection
Type
Class
LPJ_SP
TCF
LPS-RK_SP
FRS-R
LPJ_SP
TCF
LPS-RK_SP
FRS-R
LPJ_SP
TCF
LPS-RK_SP
FRS-R
LPJ_SP
TCF
LPS-RK_SP
FRS-R
LPJ_SP
TCF
LPS-RK_SP
FRS-R
LPJ_SP
TCF
LPS-RK_SP
FRS-R
LPJ_SP
TCF
LPS-RK_SP
FRS-R
LPJ_SP
TCF
LPS-RK_SP
FRS-R
LPJ_SP
LPS-RK_SP
FRS-R
LPJ_SP
LPS-RK_SP
FRS-R
LPJ_SP
LPS-RK_SP
FRS-R
LPJ_SP
LPS-RK_SP
FRS-R
LPJ_SP
LPS-RK_SP
FRS-R
LPJ_SP
LPS-RK_SP
FRS-R
KRP-C_SP
LPJ_SP
LPS-RK_SP
FRS-R
KRP-C_SP
LPJ_SP
LPS-RK_SP
FRS-R
KRP-C_SP
LPS-RK_SP
FRS-R
KRP-C_SP
KRP-C_SP
FRS-R
KRP-C_SP
KRP-C_SP
J
Jƒ
RK1
RK5
J
Jƒ
RK1
RK5
J
Jƒ
RK1
RK5
J
Jƒ
RK1
RK5
J
Jƒ
RK1
RK5
J
Jƒ
RK1
RK5
J
Jƒ
RK1
RK5
J
Jƒ
RK1
RK5
J
RK1
RK5
J
RK1
RK5
J
RK1
RK5
J
RK1
RK5
J
RK1
RK5
J
RK1
RK5
L
J
RK1
RK5
L
J
RK1
RK5
L
RK1
RK5
L
L
RK5
L
L
AMPS1
17 1⁄2
17 1⁄2
15
15
25
25
20
17 1⁄2
35
35
30
30
45
45
40
35
60
60
45
45
60
60
60
50
80
80
70
70
100
100
90
90
125
110
100
150
125
125
200
175
175
250
225
200
300
250
225
400
350
300
–
500
400
400
–
600
500
500
–
600
600
–
–
600
–
–
5
NEC®
Max for
Gen. Applic
430.52(C)(1)
Exc. No. 1
AMPS1
20
20
20
20
25
25
25
25
40
40
40
40
50
50
50
50
60
60
60
60
70
70
70
70
100
100
100
100
125
–
125
125
150
150
150
175
175
175
225
225
225
300
300
300
350
350
350
450
450
450
–
600
600
600
–
–
6004
6004
700
–
–
800
1000
–
1000
1200
6
NEC® Max
for Heavy
Start
430.52(C)(1)
Exc. No. 2
AMPS1
20
20
20
20
30
30
30
30
45
45
45
45
60
60
60
60
70
70
70
70
90
90
90
90
110
–
110
110
125
–
125
125
150
150
150
200
200
200
250
250
250
350
350
350
400
400
400
500
500
500
700
–
–
–
900
–
–
–
1000
–
–
1200
1400
–
1500
1600
7
Minimum
Switch
Size
430.110
AMPS
8
Minimum
NEMA
Starter
NEMA ICS 22000
Size2
9
Minimum
Copper Wire
THWN or THHN AWG
or KCMIL
Table 310.16
Size
10
Minimum
Rigid Metallic
Conduit
Annex C
Table C8
Inches
30
1
14
1
30
1
14
1
30*
2
10
1
60
2
10**
1
60*
2
8**
1
60*
3
8**
1
100*
3
6**
3
100*
3
4**
1
100*
4
3**
1**
200
4
1**
1 1⁄4**
200*
4
2/0
1 1⁄2
200*
5
3/0
1 1⁄2
400
5
4/0
2
400*
5
350
2 1⁄2
400*
6
3/0 2/PHASE
(2) 1 1⁄2
600*
6
4/0 2/PHASE
(2) 2
600*
6
300 2/PHASE
(2) 2
600*
6
350 2/PHASE
(2 )2 1⁄2
1200*
1200*
7
7
400 2/PHASE
500 2/PHASE
(2) 2 1⁄2
(2) 3
⁄2
⁄2
⁄2
⁄2
⁄2**
⁄2**
⁄4**
Switch size must be increased if the amp rating of the fuse exceeds the amp rating of the switch.
Per 430.52(C)(2), if the motor controller manufacturer’s overload relay tables state a maximum branch circuit protective device of a lower rating, that lower rating must be used in lieu of the sizes shown in Columns 4, 5, or 6.
If equipment terminations are rated for 60°C conductors only, the 60°C conductor ampacities must be utilized and therefore larger conductor sizes or conduit sizes may be required.
Limited by 600 amp being the largest amp rating for FRS-R and LPS-RK_SP.
Class J performance, special finger-safe dimensions.
©2005 Cooper Bussmann
151
Motor Circuit Protection Tables
575Vac Three-Phase Motors & Circuits (550-600Vac Systems)
1
Motor
Size
Table
430.250
HP
2
Motor
FLA
Table
430.250
AMPS
⁄2
0.9
3
⁄4
1.3
1
1.7
1 1⁄2
2.4
2
2.7
3
3.9
5
6.1
1
7 1⁄2
9
10
11
15
17
20
22
25
27
30
32
40
41
50
52
3
Fuse
4
Optimal
Branch Ckt
Protection
Type
Class
LPJ_SP
TCF
LP-CC
LPS-RK_SP
FRS-R
LPJ_SP
TCF
LP-CC
LPS-RK_SP
FRS-R
LPJ_SP
TCF
LP-CC
LPS-RK_SP
FRS-R
LPJ_SP
TCF
LP-CC
LPS-RK_SP
FRS-R
LPJ_SP
TCF
LP-CC
LPS-RK_SP
FRS-R
LPJ_SP
TCF
LP-CC
LPS-RK_SP
FRS-R
LPJ_SP
TCF
LP-CC
LPS-RK_SP
FRS-R
LPJ_SP
TCF
LP-CC
LPS-RK_SP
FRS-R
LPJ_SP
TCF
LPS-RK_SP
FRS-R
LPJ_SP
TCF
LPS-RK_SP
FRS-R
LPJ_SP
TCF
LPS-RK_SP
FRS-R
LPJ_SP
TCF
LPS-RK_SP
FRS-R
LPJ_SP
TCF
LPS-RK_SP
FRS-R
LPJ_SP
TCF
LPS-RK_SP
FRS-R
LPJ_SP
TCF
LPS-RK_SP
FRS-R
J
Jƒ
CC
RK1
RK5
J
Jƒ
CC
RK1
RK5
J
Jƒ
CC
RK1
RK5
J
Jƒ
CC
RK1
RK5
J
Jƒ
CC
RK1
RK5
J
Jƒ
CC
RK1
RK5
J
Jƒ
CC
RK1
RK5
J
Jƒ
CC
RK1
RK5
J
Jƒ
RK1
RK5
J
Jƒ
RK1
RK5
J
Jƒ
RK1
RK5
J
Jƒ
RK1
RK5
J
Jƒ
RK1
RK5
J
Jƒ
RK1
RK5
J
Jƒ
RK1
RK5
AMPS1
1 4⁄10
3
1 8⁄10
1 1⁄4
1 1⁄8
2
3
2 8⁄10
1 8⁄10
1 8⁄10
2 8⁄10
3
3 1⁄2
2 1⁄4
2 1⁄4
4
6
5
3 2⁄10
3
4 1⁄2
6
5 6⁄10
4
3 1⁄2
6
6
5
5 6⁄10
5
10
10
15
8
8
15
15
30
12
12
17 1⁄2
17 1⁄2
15
15
30
30
25
25
35
35
30
30
45
45
40
35
50
50
45
40
70
70
60
60
80
80
70
70
5
NEC®
Max for
Gen. Applic
430.52(C)(1)
Exc. No. 1
AMPS1
3
3
3
3
3
3
3
6
3
3
3
3
6
3
3
6
6
10
6
6
6
6
10
6
6
10
10
15
10
10
15
15
20
15
15
20
20
30
20
20
20
20
20
20
30
30
30
30
40
40
40
40
50
50
50
50
60
60
60
60
80
80
80
80
100
100
100
100
6
NEC® Max
for Heavy
Start
430.52(C)(1)
Exc. No. 2
AMPS1
3
3
3 1⁄2
3
3
3
3
6
3
3
3 1⁄2
3
6 1⁄4
3 1⁄2
3 1⁄2
6
6
10
6
6
6
6
10
6
6
10
10
15
10
10
15
15
20
15
15
20
20
30
20
20
20
20
20
20
35
35
35
35
45
45
45
45
60
60
60
60
70
70
70
70
90
90
90
90
110
–
110
110
7
Minimum
Switch
Size
430.110
AMPS
8
Minimum
NEMA
Starter
NEMA ICS 22000
Size2
9
Minimum
Copper Wire
THWN or THHN AWG
or KCMIL
Table 310.16
Size
10
Minimum
Rigid Metallic
Conduit
Annex C
Table C8
Inches
30
0
14
1
30
0
14
1
30
0
14
1
30
0
14
1
30
0
14
1
30
0
14
1
30
0
14
1
30
1
14
1
30
1
14
1
30*
2
12
1
30*
2
10
1
60
2
10**
60*
3
8
1
60*
3
6
3
100*
3
6**
⁄2
⁄2
⁄2
⁄2
⁄2
⁄2
⁄2
⁄2
⁄2
⁄2
⁄2
⁄2**
1
⁄2
⁄4
⁄4**
3
*Switch size must be increased if the amp rating of the fuse exceeds the amp rating of the switch.
1 Per 430.52(C)(2), if the motor controller manufacturer’s overload relay tables state a maximum branch circuit protective device of a lower rating, that lower rating must be used in lieu of the sizes shown in Columns 4, 5, or 6.
**If equipment terminations are rated for 60°C conductors only, the 60°C conductor ampacities must be utilized and therefore larger conductor sizes or conduit sizes may be required.
2 These sizes are typical. They are not shown in NEMA ICS 2-2000.
ƒ
Class J performance, special finger-safe dimensions.
152
©2005 Cooper Bussmann
Motor Circuit Protection Tables
575Vac Three-Phase Motors & Circuits (550-600Vac Systems) continued
1
Motor
Size
Table
430.250
HP
2
Motor
FLA
Table
430.250
AMPS
60
62
75
77
100
99
125
125
150
144
200
192
250
242
300
289
350
336
400
382
450
412
500
472
*
1
**
2
3
Fuse
4
Optimal
Branch Ckt
Protection
Type
Class
LPJ_SP
LPS-RK_SP
FRS-R
LPJ_SP
LPS-RK_SP
FRS-R
LPJ_SP
LPS-RK_SP
FRS-R
LPJ_SP
LPS-RK_SP
FRS-R
LPJ_SP
LPS-RK_SP
FRS-R
LPJ_SP
LPS-RK_SP
FRS-R
LPJ_SP
LPS-RK_SP
FRS-R
KRP-C_SP
LPJ_SP
LPS-RK_SP
FRS-R
KRP-C_SP
LPJ_SP
LPS-RK_SP
FRS-R
KRP-C_SP
LPJ_SP
LPS-RK_SP
FRS-R
KRP-C_SP
LPS-RK_SP
FRS-R
KRP-C_SP
FRS-R
KRP-C_SP
J
RK1
RK5
J
RK1
RK5
J
RK1
RK5
J
RK1
RK5
J
RK1
RK5
J
RK1
RK5
J
RK1
RK5
L
J
RK1
RK5
L
J
RK1
RK5
L
J
RK1
RK5
L
RK1
RK5
L
RK5
L
AMPS1
100
90
80
125
110
100
150
150
125
200
175
175
225
200
200
300
250
250
400
350
350
–
450
400
400
–
600
450
450
–
600
500
500
–
600
600
–
600
–
5
NEC®
Max for
Gen. Applic
430.52(C)(1)
Exc. No. 1
AMPS1
110
110
110
150
150
150
175
175
175
225
225
225
300
300
300
350
350
350
450
450
450
–
600
600
600
–
600
600
600
601
–
–
–
700
–
–
800
–
1000
6
NEC® Max
for Heavy
Start
430.52(C)(1)
Exc. No. 2
AMPS1
125
125
125
150
150
150
200
200
200
250
250
250
300
300
300
400
400
400
500
500
500
700
600
600
600
800
–
–
–
1000
–
–
–
1100
–
–
1200
–
1400
7
Minimum
Switch
Size
430.110
AMPS
8
Minimum
NEMA
Starter
NEMA ICS 22000
Size2
9
Minimum
Copper Wire
THWN or THHN AWG
or KCMIL
Table 310.16
Size
10
Minimum
Rigid Metallic
Conduit
Annex C
Table C8
Inches
100*
4
4**
1
100*
4
3**
1**
200
4
1**
1 1⁄4**
200*
5
2/0
1 1⁄2
200*
5
3/0
1 1⁄2
400
5
250
2
400*
6
350
2 1⁄2
400*
6
500
3
600*
6
4/0 2/PHASE
(2) 2
600*
6
250 2/PHASE
(2) 2
600*
7
300 2/PHASE
(2) 2
600*
7
350 2/PHASE
(2) 2 1⁄2
Switch size must be increased if the amp rating of the fuse exceeds the amp rating of the switch.
Per 430.52(C)(2), if the motor controller manufacturer’s overload relay tables state a maximum branch circuit protective device of a lower rating, that lower rating must be used in lieu of the sizes shown in Columns 4, 5, or 6.
If equipment terminations are rated for 60°C conductors only, the 60°C conductor ampacities must be utilized and therefore larger conductor sizes or conduit sizes may be required.
These sizes are typical. They are not shown in NEMA ICS 2-2000.
©2005 Cooper Bussmann
153
Motor Circuit Protection Tables
115Vac Single-Phase Motors & Circuits (110-120Vac Systems)
1
Motor
Size
Table
430.248
HP
2
Motor
FLA
Table
430.248
AMPS
⁄6
4.4
⁄4
5.8
⁄3
7.2
⁄2
9.8
3
⁄4
13.8
1
16
1 1⁄2
20
2
24
3
34
5
56
7 1⁄2
80
10
100
1
1
1
1
*
1
**
2
ƒ
3
Fuse
4
Optimal
Branch Ckt
Protection
Type
Class
LPJ_SP
TCF
LP-CC
LPN-RK_SP
FRN-R
LPJ_SP
TCF
LP-CC
LPN-RK_SP
FRN-R
LPJ_SP
TCF
LP-CC
LPN-RK_SP
FRN-R
LPJ_SP
TCF
LP-CC
LPN-RK_SP
FRN-R
LPJ_SP
TCF
LPN-RK_SP
FRN-R
LPJ_SP
TCF
LPN-RK_SP
FRN-R
LPJ_SP
TCF
LPN-RK_SP
FRN-R
LPJ_SP
TCF
LPN-RK_SP
FRN-R
LPJ_SP
TCF
LPN-RK_SP
FRN-R
LPJ_SP
TCF
LPN-RK_SP
FRN-R
LPJ_SP
LPN-RK_SP
FRN-R
LPJ_SP
LPN-RK_SP
FRN-R
J
Jƒ
CC
RK1
RK5
J
Jƒ
CC
RK1
RK5
J
Jƒ
CC
RK1
RK5
J
Jƒ
CC
RK1
RK5
J
Jƒ
RK1
RK5
J
Jƒ
RK1
RK5
J
Jƒ
RK1
RK5
J
Jƒ
RK1
RK5
J
Jƒ
RK1
RK5
J
Jƒ
RK1
RK5
J
RK1
RK5
J
RK1
RK5
AMPS1
8
10
9
6
5 6/10
9
10
12
8
7 1⁄2
12
15
15
10
9
15
15
30
15
15
25
25
20
17 1⁄2
25
25
25
20
30
30
30
25
40
40
35
30
60
60
45
45
90
90
80
70
125
110
100
150
150
125
5
NEC®
Max for
Gen. Applic
430.52(C)(1)
Exc. No. 1
AMPS1
10
10
15
10
10
15
15
20
15
15
15
15
25
15
15
20
20
30
20
20
25
25
25
25
30
30
30
30
35
35
35
35
45
45
45
45
60
60
60
60
100
100
100
100
150
150
150
175
175
175
6
NEC® Max
for Heavy
Start
430.52(C)(1)
Exc. No. 2
AMPS1
10
10
15
10
10
15
15
20
15
15
15
15
25
15
15
20
20
30
20
20
30
30
30
30
35
35
35
35
45
45
45
45
50
50
50
50
70
70
70
70
125
–
125
125
175
175
175
225
225
225
7
Minimum
Switch
Size
430.110
AMPS
8
Minimum
NEMA
Starter
NEMA ICS 22000
Size2
9
Minimum
Copper Wire
THWN or THHN AWG
or KCMIL
Table 310.16
Size
10
Minimum
Rigid Metallic
Conduit
Annex C
Table C8
Inches
30
00
14
1
30
00
14
1
30
00
14
1
30
0
14
1
30
0
14
1
30*
0
14
1
30*
1
12
1
30*
1
10
1
60*
2
8**
1
100*
3
4
3
100*
3
3**
1**
200*
42
1
1 1⁄4
⁄2
⁄2
⁄2
⁄2
⁄2
⁄2
⁄2
⁄2
⁄2**
⁄4**
Switch size must be increased if the amp rating of the fuse exceeds the amp rating of the switch.
Per 430.52(C)(2), if the motor controller manufacturer’s overload relay tables state a maximum branch circuit protective device of a lower rating, that lower rating must be used in lieu of the sizes shown in Columns 4, 5, or 6.
If equipment terminations are rated for 60°C conductors only, the 60°C conductor ampacities must be utilized and therefore larger conductor sizes or conduit sizes may be required.
These sizes are typical. They are not shown in NEMA ICS 2-2000.
Class J performance, special finger-safe dimensions.
154
©2005 Cooper Bussmann
Motor Circuit Protection Tables
230Vac Single-Phase Motors & Circuits (220-240Vac Systems)
1
Motor
Size
Table
430.248
HP
2
Motor
FLA
Table
430.248
AMPS
⁄6
2.2
⁄4
2.9
⁄3
3.6
⁄2
4.9
3
⁄4
6.9
1
8
1 1⁄2
10
2
12
3
17
5
28
7 1⁄2
40
10
50
1
1
1
1
3
Fuse
4
Optimal
Branch Ckt
Protection
Type
Class
LPJ_SP
TCF
LP-CC
LPN-RK_SP
FRN-R
LPJ_SP
TCF
LP-CC
LPN-RK_SP
FRN-R
LPJ_SP
TCF
LP-CC
LPN-RK_SP
FRN-R
LPJ_SP
TCF
LP-CC
LPN-RK_SP
FRN-R
LPJ_SP
TCF
LP-CC
LPN-RK_SP
FRN-R
LPJ_SP
TCF
LP-CC
LPN-RK_SP
FRN-R
LPJ_SP
TCF
LP-CC
LPN-RK_SP
FRN-R
LPJ_SP
TCF
LP-CC
LPN-RK_SP
FRN-R
LPJ_SP
TCF
LPN-RK_SP
FRN-R
LPJ_SP
TCF
LPN-RK_SP
FRN-R
LPJ_SP
TCF
LPN-RK_SP
FRN-R
LPJ_SP
TCF
LPN-RK_SP
FRN-R
J
Jƒ
CC
RK1
RK5
J
Jƒ
CC
RK1
RK5
J
Jƒ
CC
RK1
RK5
J
Jƒ
CC
RK1
RK5
J
Jƒ
CC
RK1
RK5
J
Jƒ
CC
RK1
RK5
J
Jƒ
CC
RK1
RK5
J
Jƒ
CC
RK1
RK5
J
Jƒ
RK1
RK5
J
Jƒ
RK1
RK5
J
Jƒ
RK1
RK5
J
Jƒ
RK1
RK5
AMPS1
3 1⁄2
6
4 1⁄2
3
2 8⁄10
4 1⁄2
6
6
4
4
5 6⁄10
6
7
5
4 1⁄2
8
10
10
8
6 1⁄4
12
15
15
9
9
12
15
25
12
10
15
15
30
15
15
20
20
25
17 1⁄2
15
30
30
25
25
45
45
40
35
60
60
60
50
80
80
70
70
5
NEC®
Max for
Gen. Applic
430.52(C)(1)
Exc. No. 1
AMPS1
6
6
10
6
6
6
6
10
6
6
10
10
15
10
10
10
10
15
10
10
15
15
25
15
15
15
15
25
15
15
20
20
30
20
20
25
25
–
25
25
30
30
30
30
50
50
50
50
70
70
70
70
90
90
90
90
6
NEC® Max
for Heavy
Start
430.52(C)(1)
Exc. No. 2
AMPS1
6
6
10
6
6
6
6
10
6 1⁄4
6 1⁄4
10
10
15
10
10
10
10
15
10
10
15
15
25
15
15
17 1⁄2
17 1⁄2
30
17 1⁄2
17 1⁄2
20
20
30
20
20
25
25
–
25
25
35
35
35
35
60
60
60
60
90
90
90
90
110
–
110
110
7
Minimum
Switch
Size
430.110
AMPS
8
Minimum
NEMA
Starter
NEMA ICS 22000
Size2
9
Minimum
Copper Wire
THWN or THHN AWG
or KCMIL
Table 310.16
Size
10
Minimum
Rigid Metallic
Conduit
Annex C
Table C8
Inches
30
00
14
1
30
00
14
1
30
00
14
1
30
00
14
1
30
00
14
1
30
00
14
1
30
0
14
1
30
0
14
1
30*
1
12
1
60
2
10**
1
60*
2
8**
1
100*
3
6**
1
⁄2
⁄2
⁄2
⁄2
⁄2
⁄2
⁄2
⁄2
⁄2
⁄2
⁄2**
⁄2**
* Switch size must be increased if the amp rating of the fuse exceeds the amp rating of the switch.
1 Per 430.52(C)(2), if the motor controller manufacturer’s overload relay tables state a maximum branch circuit protective device of a lower rating, that lower rating must be used in lieu of the sizes shown in Columns 4, 5, or 6.
** If equipment terminations are rated for 60°C conductors only, the 60°C conductor ampacities must be utilized and therefore larger conductor sizes or conduit sizes may be required.
ƒ
Class J performance, special finger-safe dimensions.
©2005 Cooper Bussmann
155
Motor Circuit Protection Tables
90Vdc3 Motors & Circuits
1
Motor
Size
Table
430.257
HP
2
Motor
FLA
Table
430.257
AMPS
⁄4
4.0
⁄3
5.2
⁄2
6.8
⁄4
9.6
1
1
1
3
1
**
2
3
ƒ
3
Fuse
4
Optimal
Branch Ckt
Protection
Type
Class
LPJ_SP
TCF
LPC_CC
LPN-RK_SP
FRN-R
LPJ_SP
TCF
LP-CC
LPN-RK_SP
FRN-R
LPJ_SP
TCF
LP-CC
LPN-RK_SP
FRN-R
LPJ_SP
TCF
LP-CC
LPN-RK_SP
FRN-R
J
Jƒ
CC
RK1
RK5
J
Jƒ
CC
RK1
RK5
J
Jƒ
CC
RK1
RK5
J
Jƒ
CC
RK1
RK5
AMPS1
6
6
6
6
5
8
10
10
8
7
12
15
15
9
9
15
15
15
15
12
5
NEC®
Max for
Gen. Applic
430.52(C)(1)
Exc. No. 1
AMPS1
6
6
6
6
6
10
10
10
10
10
15
15
15
15
15
15
15
15
15
15
6
NEC® Max
for Heavy
Start
430.52(C)(1)
Exc. No. 2
AMPS1
6
6
15
9
9
10
10
20
10
10
15
15
25
15
15
20
20
30
20
20
7
Minimum
Switch
Size
430.110
AMPS
8
Minimum
NEMA
Starter
NEMA ICS 22000
Size2
9
Minimum
Copper Wire
THWN or THHN AWG
or KCMIL
Table 310.16
Size
10
Minimum
Rigid Metallic
Conduit
Annex C
Table C8
Inches
30
1
14
1
30
1
14
1
30
1
14
1
30
1
14
1
⁄2
⁄2
⁄2
⁄2
Per 430.52(C)(2), if the motor controller manufacturer’s overload relay tables state a maximum branch circuit protective device of a lower rating, that lower rating must be used in lieu of the sizes shown in Columns 4, 5, or 6.
If equipment terminations are rated for 60°C conductors only, the 60°C conductor ampacities must be utilized and therefore larger conductor sizes or conduit sizes may be required.
These sizes are typical. They are not shown in NEMA ICS 2-2000.
All equipment manufacturers should be consulted about DC voltage ratings of their equipment.
Class J performance, special finger-safe dimensions.
156
©2005 Cooper Bussmann
Motor Circuit Protection Tables
120Vdc3 Motors & Circuits
1
Motor
Size
Table
430.257
HP
2
Motor
FLA
Table
430.257
AMPS
⁄4
3.1
⁄3
4.1
⁄2
5.4
3
⁄4
7.6
1
9.5
1 1⁄2
13.2
1
1
1
2
17
3
25
5
40
7 1⁄2
58
10
76
*
1
**
2
3
5
ƒ
3
Fuse
4
Optimal
Branch Ckt
Protection
Type
Class
LPJ_SP
TCF
LP-CC
LPN-RK_SP
FRN-R
LPJ_SP
TCF
LP-CC
LPN-RK_SP
FRN-R
LPJ_SP
TCF
LP-CC
LPN-RK_SP
FRN-R
LPJ_SP
TCF
LP-CC
LPN-RK_SP
FRN-R
LPJ_SP
TCF
LP-CC
LPN-RK_SP
FRN-R
LPJ_SP
TCF
LP-CC
LPN-RK_SP
FRN-R
LPJ_SP
TCF
LP-CC
LPN-RK_SP
FRN-R
LPJ_SP
TCF
LPN-RK_SP
FRN-R
LPJ_SP
TCF
LPN-RK_SP
FRN-R
LPJ_SP
TCF
LPN-RK_SP
FRN-R
LPJ_SP
LPN-RK_SP
FRN-R
J
Jƒ
CC
RK1
RK5
J
Jƒ
CC
RK1
RK5
J
Jƒ
CC
RK1
RK5
J
Jƒ
CC
RK1
RK5
J
Jƒ
CC
RK1
RK5
J
Jƒ
CC
RK1
RK5
J
Jƒ
CC
RK1
RK5
J
Jƒ
RK1
RK5
J
Jƒ
RK1
RK5
J
Jƒ
RK1
RK5
J
RK1
RK5
AMPS1
5
6
6
4 1⁄2
4
7
10
9
5 6⁄10
5 6⁄10
9
10
10
7 1⁄2
7
12
15
15
10
10
15
15
15
15
12
20
20
20
17 1⁄2
17 1⁄2
30
30
30
25
25
40
40
35
35
60
60
60
50
90
90
80
80
125
100
100
5
NEC®
Max for
Gen. Applic
430.52(C)(1)
Exc. No. 1
AMPS1
6
6
6
6
6
10
10
10
10
10
10
10
10
10
10
15
15
15
15
15
15
15
15
15
15
20
20
20
20
20
30
30
30
30
30
40
40
40
40
60
60
60
60
90
90
90
90
125
125
125
6
NEC® Max
for Heavy
Start
430.52(C)(1)
Exc. No. 2
AMPS1
6
6
12
6 1⁄4
6 1⁄4
10
10
15
10
10
12
10
20
12
12
15
15
30
15
15
20
20
305
20
20
25
25
305
25
25
35
35
305
35
35
50
50
50
35
90
60
90
90
125
–
125
125
150
150
150
7
Minimum
Switch
Size
430.110
AMPS
8
Minimum
NEMA
Starter
NEMA ICS 22000
Size2
9
Minimum
Copper Wire
THWN or THHN AWG
or KCMIL
Table 310.16
Size
10
Minimum
Rigid Metallic
Conduit
Annex C
Table C8
Inches
30
1
14
1
30
1
14
1
30
1
14
1
30
1
14
1
30
1
14
1
30
1
14
1
30*
1
12
1
60
1
10**
1
60*
2
8**
1
100*
3
4**
3
100*
3
3**
⁄2
⁄2
⁄2
⁄2
⁄2
⁄2
⁄2
⁄2
⁄2**
⁄4**
1
Switch size must be increased if the amp rating of the fuse exceeds the amp rating of the switch.
Per 430.52(C)(2), if the motor controller manufacturer’s overload relay tables state a maximum branch circuit protective device of a lower rating, that lower rating must be used in lieu of the sizes shown in Columns 4, 5, or 6.
If equipment terminations are rated for 60°C conductors only, the 60°C conductor ampacities must be utilized and therefore larger conductor sizes or conduit sizes may be required.
Reduced voltage magnetic controller ratings
All equipment manufacturers should be consulted about DC voltage ratings of their equipment.
Largest LP-CC Fuse 30 amp. With other type fuse, could use larger amp rating in this application.
Class J performance, special finger-safe dimensions.
©2005 Cooper Bussmann
157
Motor Circuit Protection Tables
180Vdc3 Motors & Circuits
1
Motor
Size
Table
430.257
HP
2
Motor
FLA
Table
430.257
AMPS
⁄4
2.0
⁄3
2.6
⁄2
3.4
3
⁄4
4.8
1
6.1
1 1⁄2
8.3
2
10.8
3
16
5
27
1
1
1
*
1
**
2
3
ƒ
3
Fuse
4
Optimal
Branch Ckt
Protection
Type
Class
LPJ_SP
TCF
LPS-RK_SP
FRS-R
LPJ_SP
TCF
LPS-RK_SP
FRS-R
LPJ_SP
TCF
LPS-RK_SP
FRS-R
LPJ_SP
TCF
LPS-RK_SP
FRS-R
LPJ_SP
TCF
LPS-RK_SP
FRS-R
LPJ_SP
TCF
LP-CC
LPS-RK_SP
FRS-R
LPJ_SP
TCF
LP-CC
LPS-RK_SP
FRS-R
LPJ_SP
TCF
LP-CC
LPS-RK_SP
FRS-R
LPJ_SP
TCF
LPS-RK_SP
FRS-R
J
Jƒ
RK1
RK5
J
Jƒ
RK1
RK5
J
Jƒ
RK1
RK5
J
Jƒ
RK1
RK5
J
Jƒ
RK1
RK5
J
Jƒ
CC
RK1
RK5
J
Jƒ
CC
RK1
RK5
J
Jƒ
CC
RK1
RK5
J
Jƒ
RK1
RK5
AMPS1
3
3
2 8⁄10
2 1⁄2
4
6
3 1⁄2
3 1⁄2
5 6⁄10
6
4 1⁄2
4 1⁄2
8
10
6 1⁄4
6
10
10
8
8
15
15
–
12
12
15
15
20
15
15
25
25
25
20
20
40
40
40
35
5
NEC®
Max for
Gen. Applic
430.52(C)(1)
Exc. No. 1
AMPS1
3
3
3
3
6
6
6
6
6
6
6
6
10
10
10
10
10
10
10
10
15
15
–
15
15
20
20
20
20
20
25
25
25
25
25
45
45
45
45
6
NEC® Max
for Heavy
Start
430.52(C)(1)
Exc. No. 2
AMPS1
4 1⁄2
3
4 1⁄2
4 1⁄2
6
6
6
6
6
6
6 1⁄4
7 1⁄2
10
10
10
10
12
10
12
12
17 1⁄2
15
30
17 1⁄2
17 1⁄2
20
20
30
20
20
35
35
30
35
35
60
60
60
60
7
Minimum
Switch
Size
430.110
AMPS
8
Minimum
NEMA
Starter
NEMA ICS 22000
Size2
9
Minimum
Copper Wire
THWN or THHN AWG
or KCMIL
Table 310.16
Size
10
Minimum
Rigid Metallic
Conduit
Annex C
Table C8
Inches
30
1
14
1
30
1
14
1
30
1
14
1
30
1
14
1
30
1
14
1
30
1
14
1
30
1
14
1
30*
1
14
1
60
2
10**
1
⁄2
⁄2
⁄2
⁄2
⁄2
⁄2
⁄2
⁄2
⁄2
Switch size must be increased if the amp rating of the fuse exceeds the amp rating of the switch.
Per 430.52(C)(2), if the motor controller manufacturer’s overload relay tables state a maximum branch circuit protective device of a lower rating, that lower rating must be used in lieu of the sizes shown in Columns 4, 5, or 6.
If equipment terminations are rated for 60°C conductors only, the 60°C conductor ampacities must be utilized and therefore larger conductor sizes or conduit sizes may be required.
These sizes are typical. They are not shown in NEMA ICS 2-2000.
All equipment manufacturers should be consulted about DC voltage ratings of their equipment.
Class J performance, special finger-safe dimensions.
240Vdc3 Motors & Circuits
1
Motor
Size
Table
430.257
HP
2
Motor
FLA
Table
430.257
AMPS
⁄4
1.6
⁄3
2.0
1
1
*
1
**
2
3
ƒ
3
Fuse
4
Optimal
Branch Ckt
Protection
Type
Class
LPJ_SP
TCF
LPN-RK_SP
FRS-R
LPJ_SP
TCF
LPS-RK_SP
FRS-R
J
Jƒ
RK1
RK5
J
Jƒ
RK1
RK5
AMPS1
2 1⁄2
3
2 1⁄4
2
3
3
2 8⁄10
2 1⁄2
5
NEC®
Max for
Gen. Applic
430.52(C)(1)
Exc. No. 1
AMPS1
3
3
3
3
3
3
3
3
6
NEC® Max
for Heavy
Start
430.52(C)(1)
Exc. No. 2
AMPS1
3 1⁄2
3
3 1⁄2
3 1⁄2
4 1⁄2
3
4 1⁄2
4 1⁄2
7
Minimum
Switch
Size
430.110
AMPS
8
Minimum
NEMA
Starter
NEMA ICS 22000
Size2
9
Minimum
Copper Wire
THWN or THHN AWG
or KCMIL
Table 310.16
Size
10
Minimum
Rigid Metallic
Conduit
Annex C
Table C8
Inches
30
1
14
1
30
1
14
1
⁄2
⁄2
Switch size must be increased if the amp rating of the fuse exceeds the amp rating of the switch.
Per 430.52(C)(2), if the motor controller manufacturer’s overload relay tables state a maximum branch circuit protective device of a lower rating, that lower rating must be used in lieu of the sizes shown in Columns 4, 5, or 6.
If equipment terminations are rated for 60°C conductors only, the 60°C conductor ampacities must be utilized and therefore larger conductor sizes or conduit sizes may be required.
Reduced voltage magnetic DC controller ratings.
All equipment manufacturers should be consulted about DC voltage ratings of their equipment.
Class J performance, special finger-safe dimensions.
158
©2005 Cooper Bussmann
Motor Circuit Protection Tables
240Vdc3 Motors & Circuits continued
1
Motor
Size
Table
430.257
HP
2
Motor
FLA
Table
430.257
AMPS
⁄2
2.7
3
⁄4
3.8
1
4.7
1 1⁄2
6.6
2
8.5
3
12.2
5
20
7 1⁄2
29
10
38
15
55
20
72
25
89
30
106
40
140
50
173
60
206
75
255
100
341
1
*
1
**
2
3
ƒ
3
Fuse
4
Optimal
Branch Ckt
Protection
Type
Class
LPJ_SP
TCF
LPS-RK_SP
FRS-R
LPJ_SP
TCF
LP-CC
LPS-RK_SP
FRS-R
LPJ_SP
TCF
LPS-RK_SP
FRS-R
LPJ_SP
TCF
LPS-RK_SP
FRS-R
LPJ_SP
TCF
LPS-RK_SP
FRS-R
LPJ_SP
TCF
LP-CC
LPS-RK_SP
FRS-R
LPJ_SP
TCF
LP-CC
LPS-RK_SP
FRS-R
LPJ_SP
TCF
LPS-RK_SP
FRS-R
LPJ_SP
TCF
LPS-RK_SP
FRS-R
LPJ_SP
TCF
LPN-RK_SP
FRS-R
LPJ_SP
LPN-RK_SP
FRS-R
LPJ_SP
LPN-RK_SP
FRS-R
LPJ_SP
LPN-RK_SP
FRS-R
LPJ_SP
LPN-RK_SP
FRS-R
LPJ_SP
LPN-RK_SP
FRS-R
LPJ_SP
LPN-RK_SP
FRS-R
LPJ_SP
LPN-RK_SP
FRS-R
LPJ_SP
LPN-RK_SP
FRS-R
J
Jƒ
RK1
RK5
J
Jƒ
CC
RK1
RK5
J
Jƒ
RK1
RK5
J
Jƒ
RK1
RK5
J
Jƒ
RK1
RK5
J
Jƒ
CC
RK1
RK5
J
Jƒ
CC
RK1
RK5
J
Jƒ
RK1
RK5
J
Jƒ
RK1
RK5
J
Jƒ
RK1
RK5
J
RK1
RK5
J
RK1
RK5
J
RK1
RK5
J
RK1
RK5
J
RK1
RK5
J
RK1
RK5
J
RK1
RK5
J
RK1
RK5
AMPS1
4 1⁄2
6
4
3 1⁄2
6
6
—
5
5
8
10
6 1⁄4
6
10
10
9
9
15
15
12
12
20
20
20
17 1⁄2
17 1⁄2
30
30
30
30
25
45
45
40
40
60
60
50
50
90
90
80
70
110
100
90
150
125
125
175
150
150
225
200
175
300
225
225
350
300
300
400
350
350
600
450
450
5
NEC®
Max for
Gen. Applic
430.52(C)(1)
Exc. No. 1
AMPS1
6
6
6
6
6
6
—
6
6
10
10
10
10
10
10
10
10
15
15
15
15
20
20
20
20
20
30
30
30
30
30
45
45
45
45
60
60
60
60
90
90
90
90
110
110
110
150
150
150
175
175
175
225
225
225
300
300
300
350
350
350
400
400
400
600
600
600
6
NEC® Max
for Heavy
Start
430.52(C)(1)
Exc. No. 2
AMPS1
6
6
6
6
8
6
15
8
8
10
10
10
10
12
10
12
12
17 1⁄2
15
17 1⁄2
17 1⁄2
25
25
30
25
25
45
45
30
45
45
60
60
60
60
80
60
80
80
110
–
110
110
150
150
150
200
200
200
225
225
225
300
300
300
350
350
350
450
450
450
500
500
500
–
–
–
7
Minimum
Switch
Size
430.110
AMPS
8
Minimum
NEMA
Starter
NEMA ICS 22000
Size2
9
Minimum
Copper Wire
THWN or THHN AWG
or KCMIL
Table 310.16
Size
10
Minimum
Rigid Metallic
Conduit
Annex C
Table C8
Inches
30
1
14
1
30
1
14
1
30
1
14
1
30
1
14
1
30
1
14
1
30
1
14
1
30*
1
12
1
60
2
8
1
60*
2
8**
100*
3
4
3/4**
100*
3
3**
1
200
3
2**
1**
200*
4
1/0**
1 1⁄4
200*
4
2/0**
1 1⁄4**
400
5
4/0**
1 1⁄2**
400*
5
300**
2**
400*
5
400**
2**
600
6
4/0 2/PHASE
(2) 1 1⁄2**
⁄2
⁄2
⁄2
⁄2
⁄2
⁄2
⁄2
⁄2
⁄2**
1
Switch size must be increased if the amp rating of the fuse exceeds the amp rating of the switch.
Per 430.52(C)(2), if the motor controller manufacturer’s overload relay tables state a maximum branch circuit protective device of a lower rating, that lower rating must be used in lieu of the sizes shown in Columns 4, 5, or 6.
If equipment terminations are rated for 60°C conductors only, the 60°C conductor ampacities must be utilized and therefore larger conductor sizes or conduit sizes may be required.
Reduced voltage magnetic DC controller ratings.
All equipment manufacturers should be consulted about DC voltage ratings of their equipment.
Class J performance, special finger-safe dimensions.
©2005 Cooper Bussmann
159
Motor Protection
Tips For Electricians & Maintenance Crews
Recommendations for Electrician and
Maintenance Crews
Often, for various reasons, motors are oversized for applications. For instance,
a 5Hp motor is installed when the load demand is only 3Hp. In these cases a
much higher degree of protection can be obtained by sizing the overload relay
elements and/or Fusetron and Low-Peak dual-element, time-delay fuses
based on the actual full-load current draw.
460V.
5 Amperes
1. Preferable – With a clamp-on meter, determine running RMS current when the
motor is at normal full-load. (Be sure this current does not exceed nameplate
current rating.) The advantage of this method is realized when a lightly loaded
motor (especially those over 50 HP) experiences a single-phase condition. Even
though the relays and fuses may be sized correctly based on motor nameplate,
circulating currents within the motor may cause damage.
READ NAMEPLATE
5 Amperes
460V.
Alternate – if unable to meter the motor current, then take the current rating off
the nameplate.
FRS-R 61/4
460V.
2. Then size the overload relay elements and Fusetron FRS-R and FRN-R or LowPeak LPS-RK_SP and LPN-RK_SP dual-element fuses based on this current. For
optimum motor circuit protection offering a high degree of “back-up overload”
protection, use the table that follows to assist in sizing dual-element fuses. The
other fuses in the table LPJ_SP, TCF and LP-CC can provide excellent short circuit
protection when sized for Optimum Motor Circuit Protection. However, they typically
can not be sized close enough to provide motor back-up overload protection.
3. Use a labeling system to mark the type and amp rating of the fuse that should be
in the fuse clips, such as FRS-R 6 1/4. This simple step makes it easy to run spot
checks for proper fuse replacement. When installing the proper fuses in the switch
to give the desired level of protection, it often is advisable to leave spare fuses on
top of the disconnect, the starter enclosure or in a cabinet adjacent to the motor
control center. In this way, should the fuses open, the problem can be corrected
and proper size fuses easily reinstalled.
*
Abnormal installations may require Fusetron or Low-Peak dual-element fuses of a larger size than shown providing only short circuit protection. These applications include:
(a) Fusetron or Low-Peak dual-element fuses in high ambient temperature environments.
(b) A motor started frequently or rapidly reversed.
Selection of Fusetron or Low-Peak Dual-Element
Fuses based upon Motor FLA for Optimum Motor
Circuit Protection*
Fusetron or
Low-Peak
DualElement
Fuse Size
1
⁄10
1
⁄8
15
⁄100
2
⁄10
1
⁄4
3
⁄10
4
⁄10
1
⁄2
6
⁄10
8
⁄10
1
1 1⁄8
1 1⁄4
1 4⁄10
1 1⁄2
1 6⁄10
1 8⁄10
2
2 1⁄4
2 1⁄2
2 8⁄10
3
3 2⁄10
3 1⁄2
4
4 1⁄2
5
5 6⁄10
6
6 1⁄4
7
7 1⁄2
8
9
10
12
15
17 1⁄2
20
25
30
35
40
45
50
60
70
75
80
90
100
110
125
150
175
200
225
250
300
350
400
450
500
600
FRN-R
FRS-R
Class RK5
0-0.08
0.09-0.10
0.11-0.12
0.13-0.16
0.17-0.20
0.21-0.24
0.25-0.32
0.33-0.40
0.41-0.48
0.49-0.64
0.65-0.80
0.81-0.90
0.91-1.00
1.01-1.12
1.13-1.20
1.21-1.28
1.29-1.44
1.45-1.60
1.61-1.80
1.81-2.00
2.01-2.24
2.25-2.40
2.41-2.56
2.57-2.80
3.81-3.20
3.21-3.60
3.61-4.00
4.01-4.48
4.49-4.80
4.81-5.00
5.01-5.60
5.61-6.00
6.01-6.40
6.41-7.20
7.21-8.00
8.01-9.60
9.61-12.00
12.01-14.00
14.01-16.00
16.01-20.00
20.01-24.00
24.01-28.00
28.01-32.00
32.01-36.00
36.01-40.00
40.01-48.00
48.01-56.00
56.01-60.00
60.01-64.00
64.01-72.00
72.01-80.00
80.01-88.00
88.01-100.00
100.01-120.00
120.01-140.00
140.01-160.00
160.01-180.00
180.01-200.00
200.01-240.00
240.01-280.00
280.01-320.00
320.01-360.00
360.01-400.00
400.01-480.00
Motor Current
LPN-RK_SP
LPS-RK_SP
LPJ_SP
Class RK1
Class J
0.0000-0.0769
—
0.0770-0.0961
—
0.0962-0.1153
—
0.1154-0.1538
—
0.1539-0.1923
—
0.1924-0.2307
—
0.2308-0.3076
—
0.3077-0.3846
—
0.3847-0.4615
—
0.4616-0.6153
—
0.6154-0.7692
0.0-0.6666
0.7693-0.8653
0.6667-0.7500
0.8654-0.9615
0.7501-0.8333
0.9616-1.076
0.8334-0.9333
1.077-1.153
0.9334-1.000
1.154-1.230
1.001-1.066
1.231-1.384
1.067-1.200
1.385-1.538
1.201-1.333
1.539-1.730
1.334-1.500
1.731-1.923
1.501-1.666
1.924-2.153
1.667-1.866
2.154-2.307
1.867-2.000
2.308-2.461
2.001-2.133
2.462-2.692
2.134-2.333
2.693-3.076
2.334-2.666
3.077-3.461
2.667-3.000
3.462-3.846
3.001-3.333
3.847-4.307
3.334-3.733
4.308-4.615
3.734-4.000
4.616-4.807
—
4.808-5.384
4.001-4.666
—
—
5.385-6.153
4.667-5.333
6.154-6.923
5.334-6.000
6.924-7.692
6.001-6.666
7.693-9.230
6.667-8.000
9.231-11.53
8.001-10.00
11.54-13.46
10.01-11.66
13.47-15.38
11.67-13.33
15.39-19.23
13.34-16.66
19.24-23.07
16.67-20.00
23.08-26.92
20.01-23.33
26.93-30.76
23.34-26.66
30.77-34.61
26.67-30.00
34.62-38.46
30.01-33.33
38.47-46.15
33.34-40.00
46.16-53.84
40.01-46.66
—
—
53.85-61.53
46.67-53.33
61.54-69.23
53.34-60.00
69.24-76.92
60.01-66.66
76.93-84.61
66.67-73.33
84.62-96.15
73.34-83.33
96.16-115.3
83.34-100.0
115.4-134.6
100.1-116.6
134.7-153.8
116.7-133.3
153.9-173.0
133.4-150.0
173.1-192.3
150.1-166.6
192.4-230.7
166.7-200.0
230.8-269.2
200.1-233.3
269.3-307.6
233.4-266.6
307.7-346.1
266.7-300.0
346.2-384.6
300.1-333.3
384.7-461.5
333.4-400.0
LP-CC
Class CC
—
—
—
—
—
—
—
0.0000-0.2500
0.2501-0.3000
0.3001-0.4000
0.4001-0.5000
0.5001-0.5625
0.5626-0.6250
0.6251-0.7000
0.7001-0.7500
0.7501-0.8000
0.8001-0.9000
0.9001-1.000
1.001-1.125
1.126-1.250
1.251-1.400
1.401-1.500
1.501-1.600
1.601-1.750
1.751-2.000
2.001-2.250
2.251-2.500
2.501-2.800
2.801-3.000
3.001-3.125
3.126-3.500
3.501-3.750
3.751-4.000
4.001-4.500
4.501-5.000
5.001-6.000
6.001-7.500
7.501-8.750
8.751-10.00
10.01-12.50
12.51-15.00
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
(c) Motor is directly connected to a machine that cannot be brought up to full speed
quickly (large fans, centrifugal machines such as extractors and pulverizers, machines
having large fly wheels such as large punch presses.)
(d) Motor has a high Code Letter (or possibly no Code Letter) with full voltage start.
(e) WYE delta open transition start.
(f) Motor has a large inrush current, such as a Design B.
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©2005 Cooper Bussmann