Distribution Service - Feeder Circuits-Code compliance
Distribution Service - Feeder Circuits-Code compliance
(OP)
I have a project where I am trying to install equipment for distribution service to two different buildings in a substation facility.
The distribution service from a normal and alternate source will be fed via ATS (located on the inner wall of first kysor building- Control Center#2) to two 225A panels via 225A breakers. The service cable from ATS will also be fed to the second building (Control Center #1)150A breaker via a 225A breaker located isnde CC#2.
Please refer to the attached drawing. (service side of ATS not shown)
My question for you all is, do you see any code violation?
Does it comply with NEC 230.3? If not, what is the reasoning behind complying with NEC 230.3?
Also, most importantly are you aware of any breaker panel, which would carry all three 225A breakers within one assembly (items inside dashed line) and has a small form factor to be mounted inside control center 2?
I will appreciate your advice.
The distribution service from a normal and alternate source will be fed via ATS (located on the inner wall of first kysor building- Control Center#2) to two 225A panels via 225A breakers. The service cable from ATS will also be fed to the second building (Control Center #1)150A breaker via a 225A breaker located isnde CC#2.
Please refer to the attached drawing. (service side of ATS not shown)
My question for you all is, do you see any code violation?
Does it comply with NEC 230.3? If not, what is the reasoning behind complying with NEC 230.3?
Also, most importantly are you aware of any breaker panel, which would carry all three 225A breakers within one assembly (items inside dashed line) and has a small form factor to be mounted inside control center 2?
I will appreciate your advice.






RE: Distribution Service - Feeder Circuits-Code compliance
Define "small form factor".
RE: Distribution Service - Feeder Circuits-Code compliance
The service is fed from ATS, where it's switched between distribution service provider and emergency generator.
Since the ATS is going to be in CC#2 then in order to provide service to CC#1 I will have to reroute the conductor from load side of ATS to CC#1. I am trying to figure out if the way I proposed is ok.
RE: Distribution Service - Feeder Circuits-Code compliance
RE: Distribution Service - Feeder Circuits-Code compliance
RE: Distribution Service - Feeder Circuits-Code compliance
RE: Distribution Service - Feeder Circuits-Code compliance
At the least, you will need to clearly identify number and location of the main disconnects that need to be opened to cutoff total power to a structure in case of an emergency.
Rafiq Bulsara
http://www.srengineersct.com
RE: Distribution Service - Feeder Circuits-Code compliance
to answer your question. I am looking for a panelboard that only has a place for three or four 225A thermal magnetic breakers that's it. You got any that comes to mind?
rbulsara,
we don't have a dual service issue here. Only one service will be fed to all structures at a time, whether it be distribution service or emergency generator.
Could you advise which code requires main disconnect at each structure? Also, does the code identify the location of this disconnect? (inside/outside)
The breakers are supposed to be serving as overcurrent protection and emergency disconnect.
RE: Distribution Service - Feeder Circuits-Code compliance
RE: Distribution Service - Feeder Circuits-Code compliance
Look (read) up NEC articles 220, 225 and 230 in their entirety. It is there.
Rafiq Bulsara
http://www.srengineersct.com
RE: Distribution Service - Feeder Circuits-Code compliance
Eric Kench, P.E.
RE: Distribution Service - Feeder Circuits-Code compliance
How else would you protect the feeder going to CC#1?
If there's a Short Circuit on the line going to CC#1 then you will end up taking out the AC to CC#2 as well if it were not for the breaker at CC#2 protecting that feeder. The 150A breaker at CC#1 is to be used as an overcurrent protection and emergency disconnect for the building load.
Now my question to you would be, why did this occur as odd to you?
RE: Distribution Service - Feeder Circuits-Code compliance
Eric Kench, P.E.
RE: Distribution Service - Feeder Circuits-Code compliance
The source is ahead of the ATS. The panel is the dashed line inside Control Center 2. There is a 225A breaker that feeds over to Control Center 1, a separate building. In Control Center 1, there is a building disconnect. Why 225A and 150A? That doesn't matter if the conductors between the buildings are protected by the 225A breaker. Without the 225A breaker the conductors to Control Center 1 would have to be large enough to be protected by whatever is protecting the ATS, and that would undoubtedly cost more than the 225A breaker. If the feed between Control Center 2 and Control Center 1 were protected ahead of the ATS, any problem in that circuit would take out both sources to Control Center 2, not a very good design.
I see no practical scenario under which either breaker could be removed. I'd expect a better understanding of the situation from somebody with a PE.
RE: Distribution Service - Feeder Circuits-Code compliance
RE: Distribution Service - Feeder Circuits-Code compliance
RE: Distribution Service - Feeder Circuits-Code compliance
I don't want to be designing for you, but there are other issues with your apparent design. The "star" connection shown below ATS is worriesome. The ATS ideally should be feeding a panelboard with a MCB and then branch breakers in that panel feeding the subpanels.
Also coordinating 150A and 250A breakers in series is futile as they won't. Plus the feeder needs to be sized for 250A and not 150A, etc. I hate to do this but you need some other expert eyes in your organization to look at your design.
The lack of comments here by others does not amount to approval of your design, not is this place to get your design checked.
Rafiq Bulsara
http://www.srengineersct.com
RE: Distribution Service - Feeder Circuits-Code compliance
My post here is not to get some kind of approval or reassurance from you or any other expert in this forum. The purpose of the post was to generate constructive criticism and evaluate and learn from others thought process.
Also, please define your ideal world? The situation you described may be ideal for building internal circuits, with one feeder and multiple branch circuits. I don't see how it's ideal for multiple feeders application.
Oh! by the way, If you don't have any constructive ideas or thoughts please refrain from chipping in.
davidbeach,
you are correct, there is a little bit more to the story.
The AC to the whole substation is being fed by a plant which is going away. We are establishing a new service to replace plant supply. 150A breaker is already present at CC#1 , which is currently being fed by the plant. I don't think it's cost effective to change the breaker at CC#1 since it's already sized properly for the load.
RE: Distribution Service - Feeder Circuits-Code compliance
As for my explanation of selective coordination the main circuit breaker would be protecting the feeder connected to the ATS. That circuit breaker would open last if a fault occurs in one of the parallel branches that it feeds. The smaller circuit breakers are faster and would open for any fault that occurs in the branch that it protects. I thought I made this clear.
Eric Kench, P.E.
RE: Distribution Service - Feeder Circuits-Code compliance
When you said did you mean that the 150A breaker is also properly sized with the new source's available short-circuit capacity? The 150A breaker might be okay with the old source but exceeded with the new SCMVA available from the new source.
RE: Distribution Service - Feeder Circuits-Code compliance
I am still struggling to understand your response.
Let me make sure that you are perfectly clear on the fact that CC1 circuit initiates at Control Center #2 travels about a 1000ft and then connects to 150A breaker in Control Center#1
Now, Let me rephrase what I think you are suggesting from your last post in the form of two options. Could you please pick one which you are suggesting?
1- Have no protection for the feeder at CC#2 feeding 150A breaker, which is located at CC#1
2- Have 150A breaker placed in CC#2 and no breaker in CC#1
I have a problem with both, but that's another issue. I want to make sure that I understand your suggestion clearly.