Art. 220.60 2020 NEC

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Rick 0920

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Location
Jacksonville, FL
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Electrical Instructor
Would someone help me understand this better? If my A/C is smaller than my heat, but it is the largest motor, do I use 125% of the A/C motor load in my calculation? I can understand if its my largest motor, using 25% of it in my feeder calculation steps. The CMP did not make any changes to the optional method of calculation in 220.80 for this
 

Rick 0920

Senior Member
Location
Jacksonville, FL
Occupation
Electrical Instructor
I received some clarification on this code change. It was explained to me that if your A/C is the smaller of the noncoincident loads, you take 125% of the A/C load, then compare it against the heating load. If it is still smaller than the heating load, you can omit the A/C load entirely from the calculation. I was also informed that the last sentence of 220.60 will be removed in the 2023 code because of this confusion.
 

Konen

Member
Location
Washington
Occupation
01 Electrician
Yeah this one is throwing me for a loop as well. They did not even put a period at the end of it... Will they remove it completely or be rewording it?
 

Rick 0920

Senior Member
Location
Jacksonville, FL
Occupation
Electrical Instructor
Yeah this one is throwing me for a loop as well. They did not even put a period at the end of it... Will they remove it completely or be rewording it?
I think they are planning on deleting the change entirely and going back to the way it always has been. This must have been similar to their experiment with Table 310.16 :)
 

JoeStillman

Senior Member
Location
West Chester, PA
I just tripped over this one today. Compare the language of the new text to 430.24, Exception #3;
(2020) 430.24, Exception No. 3: Where the circuitry is interlocked so as to prevent simultaneous operation of selected motors or other loads, the conductor ampacity shall be permitted to be based on the summation of the currents of the motors and other loads to be operated simultaneously that results in the highest total current.

(2020) 220.60 Where it is unlikely that two or more noncoincident loads will be in use simultaneously, it shall be permissible to use only the largest load(s) that will be used at one time for calculating the total load of a feeder or service. Where a motor is part of the noncoincident load and is not the largest of the noncoincident loads, 125 percent of the motor load shall be used in the calculation if it is the largest motor.
 
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