The Motor Protection Consultants
A Guide to Applying
Motor Circuit Controllers
U
L
Tested
According to
NEC and UL
3
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NEC 100
NEC 430-52
NEC 430-152
NEC 240-6
NEC 430-52C6
Definitions
Individual BCPDs
BCPD Selection Table
Next Size Larger BCPD
Type E Motor Controllers
NEC 430-53A
Groups 1HP or less
NEC 430-53B
Small Motor Groups
NEC 430-53C
Group Examples
Other Group Installations
Group BCPD Sizing
NEC 430-53D
Application Data
Motor Tap Rules
Additional Reference Menu
Start
from the
Top
In the Following Slides
Words in White Italics are taken directly from the
NEC
Words in captions are
interpretations of the NEC
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In the Following Slides
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6
NEC Article 100 - Definitions
Branch Circuit
The circuit conductors between
the final short-circuit device
(protecting the circuit) and the
motor load.
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NEC Article 100 - Definitions
Disconnect
A device designed to apply main
power or disconnect main power
from a branch circuit. An “At
Motor” must be within sight and
within 50 feet of the motor to
provide the maintenance
electrician a degree of safety.
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NEC Article 100 - Definitions
BCPD
Branch-Circuit
short-circuit
& ground-fault
Protection Device
Fused Device
or
Circuit Breaker
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NEC Article 100 - Definitions
Disconnect & BCPD
A single device can
incorporate the function
of Disconnect and BCPD
but this is NOT a code
requirement.
Fused Device
or
Circuit Breaker
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NEC Article 100 - Definitions
Controller
A device or group of devices
that serves to govern,
in some predetermined manner,
the electric power delivered
to the connected load.
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NEC 430-52
Selecting an
Individual Motor Circuit
BCPD
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NEC 430-52
Selecting an Individual Motor Circuit BCPD
(a) General
The motor branch-circuit short-circuit and ground-fault
protection device shall comply with (b) and either (c) or
(d), as applicable.
(b) All Motors
The motor branch-circuit short-circuit and ground-fault
protection device shall be capable of carrying the starting
current of the motor.
(c )Rating or Setting (1…7)
1- A protective device having a rating or setting not
exceeding the value calculated according to the value
given in Table 430-152 shall be used.
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NEC 430-52
Selecting an Individual Motor Circuit BCPD
The BCPD for a motor must
be selected according to
Table 430-152
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NEC Table 430-152
Maximum Rating or Setting of Motor Branch-Circuit
Short-Circuit and Ground-Fault Protective Devices
Dual
Non- Element
Time (TimeDelay Delay)
Type of Motor
Fuse
Fuse
All single-phase & AC polyphase 300% 175%
motors (other than wound-rotor)
Squirrel cage:
Other than design E
300% 175%
Design E
300% 175%
Synchronous
300% 175%
Wound rotor
150% 150%
Direct-current(constant voltage)
150% 150%
Instantaneous Inverse
Trip
Time
Breaker Breaker
800%
250%
800%
1100%
800%
800%
250%
250%
250%
250%
150%
150%
% of Full-Load Current
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NEC 430-52 C.1
Exception No. 1
Where the values for branch-circuit short-circuit and
ground-fault protective devices determined by Table 430152 do not correspond to the standard sizes or ratings of
fuses, nonadjustable circuit breakers, thermal protective
devices, or possible settings of adjustable circuit breakers,
any of which are adequate to carry the load, the next
higher size, rating, or setting shall be permitted.,
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NEC 240-6
Standard BCPD Sizes
The next standard size BCPD is
allowed if the calculation does not
match a standard size per NEC 240-6.
NEC 240-6
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Continue
NEC 430-52
Individual BCPDs
Example:
Four Starter
Power Circuit
BCPDs
Distribution
Switch
(i.e., fuses)
Contactors
Overloads
Motors
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NEC 430-152
Individual BCPD
May be one of the following:
• A non-time delay fuse
• A time delay fuse
• An inverse-time circuit breaker
(thermal-magnetic breaker)
• A magnetic-only circuit breaker
(MCP or HMCP)
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NEC 430-52 C
NEC 430-52 C contains seven options.
Option #1 was to select the BCPD from
the Table 430-152. Options 2-5 covers
applications that do not normally apply
to Motor Circuit Controllers which are
explained by the reference below &
summarized on the next slide.
Option 2-5
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Summary
NEC 430-52 C
Individual BCPD Option 1-7
OTHER
GROUP
1-C)
Select
a BCPD
fromINSTALLATIONS
the Table 430-152
consisting of fuses or circuit-breaker
2- The OLR max. amp rating of the up-stream
BCPD should not be exceeded
3- MCP’s should only be used as BCPD’s
in a UL Listed Combination starter
4- BCPD’s selected for multi-speed motors
must protect the smallest HP winding
5- I2t Fuses can be used with a solid state
controllers if a label is placed in the panel
6721
NEC 430-52 (C-Option 6)
Selecting an Individual Motor Circuit BCPD
Option 6 is new to the 1999 NEC
and the key is to understand what a
“Self-protected combination controller”
is and how this relates to UL 508
Type E approval.
(Click reference button below for details)
Option 6
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Summary
(4) Functions of a Combination Starter




National Electric Code
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NEC 430-52 C
Individual BCPD Option 1-7
1-C)
Select
a BCPD
from the
Table 430-152
OTHER
GROUP
INSTALLATIONS
consisting of fuses or circuit-breaker
2- The OLR max. amp rating of the up-stream
BCPD should not be exceeded
3- MCP’s should only be used as BCPD’s
in a UL Listed Combination starter
4- BCPD’s selected for multi-speed motors
must protect the smallest HP winding
5- I2t Fuses can be used with a solid state
controllers if a label is placed in the panel
6- UL Listed Type E Self-protected combination
controller can be a BCPD
724
NEC 430-52 C
NEC 430-52 C-Option #7 is also new in
the 1999 NEC and covers a special
application for motor circuit controllers
which are explained by the reference
below & summarized on the next slide.
Option 7
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Summary
NEC 430-52 C
Individual BCPD Option 1-7
1- Select a BCPD from the Table 430-152
C)consisting
OTHER of
GROUP
fuses orINSTALLATIONS
circuit-breaker
2- The OLR max. amp rating of the up-stream
BCPD should not be exceeded
3- MCP’s should only be used as BCPD’s
in a UL Listed Combination starter
4- BCPD’s selected for multi-speed motors
must protect the smallest HP winding
5- I2t Fuses can be used with a solid state
controllers if a label is placed in the panel
6- UL Listed Type E Self-protected combination
controller can be a BCPD
7- A short-circuit only protector can be used
as a BCPD if the assembly including the OLR
is UL Listed as a combination
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Individual BCPD
NEC 430-52 & the corresponding
sections of UL508 provides for seven
options in the use of a BCPD to protect
an individual branch circuit and a
single motor. There may be multiple
BCPD’s in a control panel.
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NEC 430-52 vs. NEC 430-53
NEC 430-52 requires individual
BCPDs to protect every motor circuit
NEC 430-53 allows for a single BCPD
to protect multiple motor circuits
in a group installation
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NEC 430-53
Group Installation Outline
Several motors or loads on 1 branch circuit
A) Not over 1HP
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or
B) If smallest motor is protected
or
C) Other group installations
NEC 430-53 A
Several motors or loads on 1 branch circuit
A) Not over 1HP
or
B) If smallest motor is protected
or
C) Other group installations
430-53A
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Summary
NEC 430-53 A
Not Over 1HP
A single BCPD not exceeding 20 Amps for 120 Volt
1-phase or 15 Amps for any circuit 208-575 Volt
(1-phase or 3-phase) may protect multiple motors if:
(1) 1800 RPM motors have an FLA < 6 Amps.
(2) The BCPD rating does not exceed the maximum
rating shown on the overload relay label.
(3) UL approved overload relays comply with 430-32.
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NEC 430-53 A
Individual BCPDs
are NOT required
Group BCPD
120V, 20A Max.
3-Phase V, 15A Max.
Contactor
BCPD rating may
not be exceeded
Motors
1HP, 6 FLA
Max. each
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NEC 430-53 B
Several motors or loads on 1 branch circuit
A) Not over 1HP
or
B) If smallest motor is protected
or
C) Other group installations
430-53B
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Summary
NEC 430-53 B
If the Smallest Motor Protected
A single BCPD may protect multiple motors and other
loads if all the following conditions are met:
(1)
BCPD shall not exceed that allowed by
430-152 to protect the smallest motor.
(2)
BCPD will not open under the inrush current
of starting and will carry the combined FLA of
motors and/or other load(s).
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NEC 430-53 B
If the Smallest Motor Protected
Example #3:
Individual BCPDs
are NOT required
Group BCPD
15A Max.
Contactors
Overloads
Motors
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2HP
3HP
NEC 430-53 A or B
Several motors or loads on 1 branch circuit
A) Group fusing is widely used under
this provision.
or B) This provision is limited to 2 or 3
motors < 5 HP and simultaneous
starting may not be allowable.
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NEC 430-53 C
Several motors or loads on 1 branch circuit
A) Not over 1HP
or
B) If smallest motor is protected
or
C) Other group installations
430-53C
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Summary
NEC 430-53 C
A Summary
C)C)
Other
Group
Installations
OTHER
GROUP
INSTALLATIONS
(1) Factory assembled multi-starter panel
or
or
and
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(2)
(3)
12345-
- with the BCPD installed
- separate BCPD and labeled panel
Field installed separate assemblies
All of the following conditions are met:
OLR must be group rated
Controller must be group rated
Circuit breakers must be thermal-magnetic type
BCPD must be sized properly
KAIC rating should be coordinated
NEC 430-53 C
A few examples might help to
clarify the selection process for
a Group Installation B.C.P.D.
Examples
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Continue
NEC 430-53 D
Single Motor Taps
This section of the NEC has caused some controversy
due to its vagueness. The reference button below will
support our interpretation.
NEC 430-53D
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Summary
NEC 430-53 D part 3
This new provisions clearly defines the sizing of motor circuit
controller wires at 1/10 that of the B.P.C.D. if the length does
not exceed 10 feet.
This means most 25 ampere frame motor circuit controller that only
allows for #10 wire maximum might be as large as 400 amperes.
This change in the 2002 NEC does require some additional testing
of the motor circuit controller under UL508 in order to mark the
device “Suitable for Tap Conductor Protection in a
Group Installation.”
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NEC 430-53 D part 3
Single Motor Taps
It is our opinion that the strict enforcement of the wire sizing options
defined by NEC 430-53D-1, -2, or -3 will force the industry to apply
Self-protected Combination Motor Controllers (Construction Type E
or Type F) in multiple motor starter panels under the provisions of
NEC 430-52-C- 6 as opposed to applying simple Group Rated Manual
Motor Circuit Controllers under Group Installations as defined under
NEC 430-53-C.
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Application of Mini-CB’s

A salesman
told me we
could use Mini-CB’s
and save money!?
There are a lot of products with
over lapping approvals and in
many cases confusion about
applicable standards resulting in
miss-application of the products
and non-compliance with UL and
NEC requirements.
Mini-CB’s
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Continue
Select for Additional Reference
Single large motor
grouped with
small motors
UL 508
Group OLRs
Location in
Control Circuit
Group Rated OLRs
Are Not BCPDs
OLR’s are
not BCPD
Single contactor
controlling a
group of motors
Continue
Group OLR
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NEC 430-87
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The Motor Protection Consultants