- Location
- Lockport, IL
- Occupation
- Semi-Retired Electrical Engineer
I am doing a service calculation of an office building, per 220. A set of three feeders supplies two elevators each. For each feeder, I know I can use a 95% demand factor, when sizing the feeder.
Question 1: Can I use the 95% demand factor for the purposes of including a feeder?s loads in the overall service load calculation? In other words, is Table 620.14 NOT ONLY talking about the ampacity of the feeder, BUT ALSO talking about the feeder?s contribution to the overall building load?
If you think the answer is yes, then go on to . . . . . .
Question 2: Can I say that the service will see a total of six elevators, and therefore use the 79% demand factor at the service level.
An Analogy: If I were talking about a two-family dwelling unit, and if each unit of the duplex had only three fixed-in-place appliances, then I could not use the 75% demand factor of 220.53 for a feeder to a single unit. But I could use that factor for the service to the duplex, since the service has six fixed-in-place appliances. This is the type of reasoning I would like to use.
The weakness in applying this analogy is that 220.53 is specifically talking about a contribution to the load calculation. On the other hand, 620.14 is talking about conductor sizing, not about service load.
Question 1: Can I use the 95% demand factor for the purposes of including a feeder?s loads in the overall service load calculation? In other words, is Table 620.14 NOT ONLY talking about the ampacity of the feeder, BUT ALSO talking about the feeder?s contribution to the overall building load?
If you think the answer is yes, then go on to . . . . . .
Question 2: Can I say that the service will see a total of six elevators, and therefore use the 79% demand factor at the service level.
An Analogy: If I were talking about a two-family dwelling unit, and if each unit of the duplex had only three fixed-in-place appliances, then I could not use the 75% demand factor of 220.53 for a feeder to a single unit. But I could use that factor for the service to the duplex, since the service has six fixed-in-place appliances. This is the type of reasoning I would like to use.
The weakness in applying this analogy is that 220.53 is specifically talking about a contribution to the load calculation. On the other hand, 620.14 is talking about conductor sizing, not about service load.
