I have a feeder feeding several Refrigerant motors. The total amperage after applying the 125% for the largest motor comes out to 93.42 amps counting 1 small cooler evaporator that is 120 volts that only pulls 4.73 amps. Is there any reduction of the neutral in a case like this or is it just applied over 200 amps? The rest of the load has no neutral. Thanks..
Also I have a 3 phase feeder. It's been a long time since I've figured up a 3 phase feeder. Do I divide the total amps by 3?? 93.42 (94 amps)/3= 31.33 ??
#209953 - 05/17/1305:51 PMRe: 3 phase feeder with only (1) 120 volt circuit
[Re: sparkync]
Also I have a 3 phase feeder. It's been a long time since I've figured up a 3 phase feeder. Do I divide the total amps by 3?? 93.42 (94 amps)/3= 31.33 ??
Are they single phase motors spread equally across the phases, or are they 3-phase motors?
#209954 - 05/17/1305:55 PMRe: 3 phase feeder with only (1) 120 volt circuit
[Re: sparkync]
220.61 Feeder or Service Neutral Load. (A) Basic Calculation. The feeder or service neutral load shall be the maximum unbalance of the load determined by this article. The maximum unbalanced load shall be the maximum net calculated load between the neutral conductor and any one ungrounded conductor. Exception: For 3-wire, 2-phase or 5-wire, 2-phase systems, the maximum unbalanced load shall be the maximum net calculated load between the neutral conductor and any one ungrounded conductor multiplied by 140 percent
I do not see anything that would make you use more than a #14 if the only unbalanced load is a 4 amp single phase motor.
In the computer room biz we never even brought a neutral beyond the service disconnect because there was never any unbalanced load. (everything was line to line)
Greg Fretwell
#209962 - 05/18/1305:34 PMRe: 3 phase feeder with only (1) 120 volt circuit
[Re: sparkync]
Thanks Greg. I just wanted to make sure there was not another rule I was missing in the code. I'll figure a bigger neutral just in case in the future they want to add something else that is 120 volts. In fact there is an old outlet attached to one of the units, that the owner said they wouldn't need, but now that I think about it, an outlet is required for "service means" on a roof top. Thanks again
#209963 - 05/18/1306:53 PMRe: 3 phase feeder with only (1) 120 volt circuit
[Re: sparkync]
