sokkerdude
Member
- Location
- Arkansas
appendix B, table-310-11 is a adjustment factor table for conductor with a 50% load diversity, Can anyone give a deffinition for "load diversity" or where it is the code.
derating current-carrying conductors
- Thread starter sokkerdude
- Start date
- Status
Re: derating current-carrying conductors
di?ver?si?ty (d?-v?r?si-te) n., pl. di?ver?si?ties. 1.a. The fact or quality of being diverse; difference. b. A point or respect in which things differ. 2. Variety or multiformity.
The word comes up 14 times in the NEC. But mostly in the commentary articles.
251.1 Scope "Commentary"
220.36 "Commentary"
Table 220.40
310.15 (B) Table "Commentary "two times"
310.15 (2) Adjustment Factors."FPN" One time, "Commentary" Two times.
400.5 "FPN"
520.44(2) "Commentary" Two times.
Table 520.44
Table B.310.11 "Two times"
Farm Loads Are very good examples were Diversity loads exist. On the feeder you could adjust for a percentage of the motor loads only running at short intervals, and not all motors running at the same time.
A grain farm is a good example. When the corn is removed, The first step is putting it in the dryer. A auger will run untill corn is loaded and then stop. Then the dryer will run for lets say 1 hour, Then shut down for a Mixer to run for ten min. Then shut down for a auger to unload into next bin to air dry. After 2 hours in the mixer then it will runs to keep corn turned. Point being no one motor is running at the same time. Or if two should run at the same time, then anyone of these steps could be happing and not the same two motors will run at the same time. It could be any two motors of any five steps of the process.
Hope that helped, Or made sense.
di?ver?si?ty (d?-v?r?si-te) n., pl. di?ver?si?ties. 1.a. The fact or quality of being diverse; difference. b. A point or respect in which things differ. 2. Variety or multiformity.
The word comes up 14 times in the NEC. But mostly in the commentary articles.
251.1 Scope "Commentary"
220.36 "Commentary"
Table 220.40
310.15 (B) Table "Commentary "two times"
310.15 (2) Adjustment Factors."FPN" One time, "Commentary" Two times.
400.5 "FPN"
520.44(2) "Commentary" Two times.
Table 520.44
Table B.310.11 "Two times"
Farm Loads Are very good examples were Diversity loads exist. On the feeder you could adjust for a percentage of the motor loads only running at short intervals, and not all motors running at the same time.
A grain farm is a good example. When the corn is removed, The first step is putting it in the dryer. A auger will run untill corn is loaded and then stop. Then the dryer will run for lets say 1 hour, Then shut down for a Mixer to run for ten min. Then shut down for a auger to unload into next bin to air dry. After 2 hours in the mixer then it will runs to keep corn turned. Point being no one motor is running at the same time. Or if two should run at the same time, then anyone of these steps could be happing and not the same two motors will run at the same time. It could be any two motors of any five steps of the process.
Hope that helped, Or made sense.
Re: derating current-carrying conductors
Load diversity: Compares the amount of load that is likely to be on at any one time against the total connected load.
Unless you are a PE and can show the calculations with a stamp, you are probable not going to be able to use it.
Load diversity: Compares the amount of load that is likely to be on at any one time against the total connected load.
Unless you are a PE and can show the calculations with a stamp, you are probable not going to be able to use it.
- Location
- Lockport, IL
- Occupation
- Semi-Retired Electrical Engineer
Re: derating current-carrying conductors
I would submit that “load diversity” has nothing to do with the total connected load. I would also agree with Dereck’s suggestion that you not try to take advantage of the table you cited, unless you have a calculation sealed and signed by a Licensed PE.
The NEC never defines the term “load diversity,” just as it never defines “volt” or “amp” or a thousand other common terms. Therefore, we are left to presume that it is a common enough term, and that we should apply the “usual definition,” as used in the industry. Unfortunately, the industry has no definition for the term either. The closest standard term, as defined in engineering textbooks, is “Diversity Factor.” It is my belief that “load diversity,” as used in the NEC, is the reciprocal of “Diversity Factor.”
The concept of “Diversity Factor” requires that an overall system be viewed as a collection of smaller subsystems. It looks at the peak load on each of the subsystems, and it looks at the peak load of the system as a whole. It is likely that not all subsystems will hit their individual peak values simultaneously. Therefore, the sum of the individual peak loads will be higher than the system’s overall peak value. “Diversity Factor” is found by dividing the “sum of the individual peak loads” by the “system’s overall peak load.” Note that this means that “Diversity Factor” will most likely be higher than 1, and that it can never be lower than 1. In comparison, “Demand Factor” is always less than or equal to 1.
I would submit that “load diversity” has nothing to do with the total connected load. I would also agree with Dereck’s suggestion that you not try to take advantage of the table you cited, unless you have a calculation sealed and signed by a Licensed PE.
The NEC never defines the term “load diversity,” just as it never defines “volt” or “amp” or a thousand other common terms. Therefore, we are left to presume that it is a common enough term, and that we should apply the “usual definition,” as used in the industry. Unfortunately, the industry has no definition for the term either. The closest standard term, as defined in engineering textbooks, is “Diversity Factor.” It is my belief that “load diversity,” as used in the NEC, is the reciprocal of “Diversity Factor.”
The concept of “Diversity Factor” requires that an overall system be viewed as a collection of smaller subsystems. It looks at the peak load on each of the subsystems, and it looks at the peak load of the system as a whole. It is likely that not all subsystems will hit their individual peak values simultaneously. Therefore, the sum of the individual peak loads will be higher than the system’s overall peak value. “Diversity Factor” is found by dividing the “sum of the individual peak loads” by the “system’s overall peak load.” Note that this means that “Diversity Factor” will most likely be higher than 1, and that it can never be lower than 1. In comparison, “Demand Factor” is always less than or equal to 1.
- Status