NEC 225.30(D)

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wyboy

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NEC 225.30(D)
I have 2 industrial-commercial buildings on the same lot owned by the same owner. One is has a 208 three phase service the other is 480 service. The 480 building has a transformer to provide 208 power where needed. The owner wants to feed the 480 building with a 208 feeder from the 208 building to supply a “house” panel. Does NEC 225.30(D) allow this install?
 

charlie b

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This is an interesting question, the likes of which I have never encountered before. But let me first check my understanding, and ask one question. I infer that the one building gets 480V from the utility, and the other building gets 208V from the utility. In other words, both are "services," as addressed in article 230. Is that right? If so, then I would want to know why the owner wants to bring 208V from the second building to the first. Is it that the existing 480V service does not have the capacity to handle a new house panel?

Now to answer the question you did ask: I would say that, no, 225.30(D) does not say that you can do what the owner is requesting. But it doesn't have to. The odd thing about this situation is that you have one service (per article 230) and one outside feeder (per article 225). Article 230 says that you can only bring one service to a building, unless you meet one of the exceptions. Article 225 says that you can only bring one outside feeder to a building, unless you meet one of the exceptions. Neither article says anything about bringing both to the same building.

Finally, I will give you my answer to the question you did not ask, the question, "would this installation be code-compliant?" I would say that the installation you are describing is not prohibited by either article 230 or 225, and therefore it is allowable.
 

Dennis Alwon

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Chapel Hill, NC
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I asked a similar question to the cmp panel here this past april. I had a detached garage with an apartment above. I wanted to feed the garage from the house panel service and have a service on the garage for the apartment above the garage. Since there was a firewall between the garage and the second floor they did not feel that this was an issue. Compliant.

I agree with Charlie in that the NEC does not quite address this but it should be fine. IMO, If you have two services on one building I don't believe there is anything that prohibits us from having circuits from both services in one building as long as the discos are grouped and identified. Knowing that I cannot see a problem with one service and one feeder serving the same building.

This begs to ask why 2 feeders are not allowed in one building? There may be something we are not seeing
 

wyboy

Senior Member
This is an interesting question, the likes of which I have never encountered before. But let me first check my understanding, and ask one question. I infer that the one building gets 480V from the utility, and the other building gets 208V from the utility. In other words, both are "services," as addressed in article 230. Is that right? If so, then I would want to know why the owner wants to bring 208V from the second building to the first. Is it that the existing 480V service does not have the capacity to handle a new house panel?

Now to answer the question you did ask: I would say that, no, 225.30(D) does not say that you can do what the owner is requesting. But it doesn't have to. The odd thing about this situation is that you have one service (per article 230) and one outside feeder (per article 225). Article 230 says that you can only bring one service to a building, unless you meet one of the exceptions. Article 225 says that you can only bring one outside feeder to a building, unless you meet one of the exceptions. Neither article says anything about bringing both to the same building.

Finally, I will give you my answer to the question you did not ask, the question, "would this installation be code-compliant?" I would say that the installation you are describing is not prohibited by either article 230 or 225, and therefore it is allowable.




Thanks for your reply: Yes, one building gets 480V from the utility, and the other building gets 208V from the utility, both are "services," The owner wants a feeder from the meter stack on the 208 building because he is renting both buildings and if the tenant in the 480 volt service building goes out of business he can spilt the building for two or more tenants and have a metered house panel serving both buildings. The question I had from 225 is each building must be fed from no more than one feeder on the load side of a service disconnect. As this building has 2 feeders-the one from building’s 480 volt service attached to the building and the 208 feeder from the other building. The exception in 225.30(D) of different voltages may allow this install; however, as there is a transformer fed from the 480 system to step down to 208 volt, are we good?
 

wyboy

Senior Member
thanks

thanks

Thanks for your reply: Yes, one building gets 480V from the utility, and the other building gets 208V from the utility, both are "services," The owner wants a feeder from the meter stack on the 208 building because he is renting both buildings and if the tenant in the 480 volt service building goes out of business he can spilt the building for two or more tenants and have a metered house panel serving both buildings. The question I had from 225 is each building must be fed from no more than one feeder on the load side of a service disconnect. As this building has 2 feeders-the one from building’s 480 volt service attached to the building and the 208 feeder from the other building. The exception in 225.30(D) of different voltages may allow this install; however, as there is a transformer fed from the 480 system to step down to 208 volt, are we good?
 

dionysius

Senior Member
Location
WA
The exception proves the rule.......not the other way round.......

The exception proves the rule.......not the other way round.......

The OP's request seems totally reasonable to me. Generally there are many (infinite!!) ways to skin a cat and codes and regulations cannot be explicit in citing all of the acceptable possibilities. They usually delineate the exceptions and by doing so tend to construct the myriad of ways that are viable.
 

tkb

Senior Member
Location
MA
Wouldn't it cost more to run a feeder from building 1 to building 2 than the cost of a dry transformer?
 
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