430.52 Rating or Setting for Individual Motor Circuit.

An example of a Design B Premium Efficient industrial motor.
Click to Enlarge
An example of a Design B Premium Efficient industrial motor.

Code Change Summary: Changes made to address Design B Premium Efficiency motors.

Design B premium efficiency motors are motors with a higher level of energy efficiency than the Design B energy-efficient motors referred to in Section 430.52 of previous editions of the NEC® (see below Table 3.3 History of Motor Efficiency Improvements from the U.S. Dept. of Energy Premium Efficiency Motor Selection and Application Guide).

Design B premium efficiency motors have largely replaced energy-efficient motor installations throughout the United States due to government regulations on energy conservation of specific electrical equipment dating back to 2010 in Title 10, Chapter II Subchapter D, Part 431 of the US Code of Federal Regulations.

In the 2023 NEC®, Section 430.52(C) as well as Table 430.52(C)(1) have been updated to include Design B Premium efficiency motors (see NEC® Table 430.52(C)(1) below).

Prior to this code change, when determining the maximum rating or setting of motor branch-circuit short-circuit and ground-fault protective devices, the values in previous Table 430.52 for Design B energy-efficient motors were also applied to Design B premium efficiency motors even though the table did not specifically mention Design B premium efficiency motors.

Table 3.3 History of Motor Efficiency Improvements (full-load efficiency in %)

HP

1944

1955 U-Frame

1965

Standard

Efficiency

1980

Standard

Efficiency

19941

Standard

Efficiency

20042

Energy

Efficiency

20123

Premium

Efficiency

7.5

84.5%

87%

84%

--

85.5%

89.5%

91.7%

15

87%

89.5%

88%

86.5%

86.6%

91.1%

92.4%

25

89.5%

90.5%

89%

88%

89.3%

92.4%

93.6%

50

90.5%

91%

91.5%

90.4%

91.3%

93.2%

94.7%

75

91%

90.5%

91.5%

90.8%

91.7%

94.1%

95.4%

100

91.5%

92%

92%

91.6%

92.3%

94.5%

95.4%

 

Table 430.52(C)(1)

Maximum Rating or Setting of Motor Branch-Circuit Short-Circuit and Ground-Fault Protective Devices

Percentage of Full-Load Current

Type of Motor

Nontime Delay

Fuse1

Dual Element

(Time-Delay)

Fuse1

Instantaneous

Trip

Breaker

Inverse

Time Breaker2

Single-phase motors

300%

175%

 800% 250%

AC polyphase motors

other than wound-rotor

300%

175%

800%

250% 

Squirrel cage — other than Design B energy-efficient — and Design B premium efficiency

300%

175%

 800% 250% 

Design B energy-efficient and Design B premium efficiency

300%

175%

1100%

250% 
 Synchronous3

300%

 175%  800% 250% 
 Wound-rotor

150%

 150%  800% 150% 
 DC (constant voltage)

150%

175%

 

250%

 150%

Did You Like This? Let Us Know With A Like! Thanks!

430.52 Rating or Setting for Individual Motor Circuit.

Below is a Real Question from our Electrical Continuing Education Courses for Electrical License Renewal:

Based on the 2023 NEC, which of the following is true?

A: Section 430.52(C) as well as Table 430.52(C)(1) have been updated to include Design B Premium Efficiency motors.
B: The NEC does NOT address Design B Premium efficiency motors in Article 430.
C: Design B Premium efficiency motors are the same as Design A efficient motors.
D: Energy efficient motors are the same as Design B Premium Efficiency motors.
Please register or sign in for electrical continuing education courses.

If you were already signed in, your session probably expired, please sign back in.