Feeders supplying loads between buildings - NEC 225.30

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Machiavelli999

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Numerous pieces of equipment are being moved out of a building's mechanical room to another small shell structure right outside the building to make room for additional equipment. We hoped to just extend existing circuits for all these mechanical equipment to the shell structure. I thought that some disconnects on the outside of the shell structure would suffice to meet NEC requirements.

However, it seems that Article 225.30 limits the number of supplies to a building to just one feeder. There are some exceptions listed including the rather vague "Documented Switching Procedures" one, but either way 225.31 still requires there to be a single disconnecting means to turn off all power to all feeders.

The single disconnecting means requirement listed in 225.31 is achievable with some relays and contacts, but can we supply a shell building with multiple feeder circuits? I would think yes....
 
Machiavelli999 said:
Numerous pieces of equipment are being moved out of a building's mechanical room to another small shell structure right outside the building to make room for additional equipment. We hoped to just extend existing circuits for all these mechanical equipment to the shell structure. I thought that some disconnects on the outside of the shell structure would suffice to meet NEC requirements.

However, it seems that Article 225.30 limits the number of supplies to a building to just one feeder. There are some exceptions listed including the rather vague "Documented Switching Procedures" one, but either way 225.31 still requires there to be a single disconnecting means to turn off all power to all feeders.

The single disconnecting means requirement listed in 225.31 is achievable with some relays and contacts, but can we supply a shell building with multiple feeder circuits? I would think yes....
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IMO, you cannot do what you want to do. You need to run a feeder out there and install a panel, drive ground rods and connect the grounding electrode conductor to the equipment grounding conductor. The neutral stays isolated. Main breaker is needed also unless you can meet the 6 handle rule for number of disconnects
 
There's a chance you can use the exception, but I suggest you contact your AHJ for their requirements and blessing. :happyyes:

Documented Switching Procedures. Additional branch cir-
cuits or feeders are allowed where documented safe switching
procedures are established and maintained.
Safe switching procedures generally include documenting
every switch and associated conductor. The primary concern
is to ensure that the two different systems (from the branch
circuits or feeders) are never connected. Such connection
could cause any number of hazardous situations. Switching
circuits are the most vulnerable to such problems, and that is
presumably why they are singled out by the NEC. Note, how-
ever, that exactly what a safe switching procedure consists of
is not mentioned by the Code and is, therefore, up to the dis-
cretion of the authority that has jurisdiction.
Click to expand...

https://books.google.com/books?id=S...ved=0ahUKEwiUlZe91tPPAhXBOCYKHR7eDxMQ6AEIPjAF
 
Machiavelli999 said:
Numerous pieces of equipment are being moved out of a building's mechanical room to another small shell structure right outside the building to make room for additional equipment. We hoped to just extend existing circuits for all these mechanical equipment to the shell structure. I thought that some disconnects on the outside of the shell structure would suffice to meet NEC requirements.

However, it seems that Article 225.30 limits the number of supplies to a building to just one feeder. There are some exceptions listed including the rather vague "Documented Switching Procedures" one, but either way 225.31 still requires there to be a single disconnecting means to turn off all power to all feeders.

The single disconnecting means requirement listed in 225.31 is achievable with some relays and contacts, but can we supply a shell building with multiple feeder circuits? I would think yes....
Click to expand...

Is the shell physically attached to the main building or not ?

Jap>
 
Dennis Alwon said:
Imo he would not fall under that exception based on what he was saying
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Well it has been argued and successful.

The single management aspect is achieved at the service location of the original building and the additional branch circuits or feeders under this allowance is something one can argue but they better understand the limitations and expressed exception for those disconnect locations in 225.32.

This was originally supposed to be for the multiple building CAMPUS style set up where they are fed from a single building with single management...However, the language as written leaves the door open for persuasive interpretation in my opinion.
 
Thank you for your responses. I wonder though what would have to happen if I wanted to feed the mechanical equipment in this shell structure from two A & B feeders. Even if I agreed to a service panel and the grounding and bonding requirements associated with that, is it still illegal for me to bring two 480V feeders to two separate panels in this building. Again so that I could feed some of the mechanical equipment off the A feed and some off of the B feed.
 
The basic rule is that you bring power to a building only once. There are exceptions, but what you have posted so far would not satisfy the exceptions. You can bring two feeders if they add up to more than 2000 amps, or if one feeder is 480V and the other is 208V. But it does not appear that either of these situations apply here. So I would have to say that your suggestion would not meet code. Sorry.
 
charlie b said:
The basic rule is that you bring power to a building only once. There are exceptions, but what you have posted so far would not satisfy the exceptions. You can bring two feeders if they add up to more than 2000 amps, or if one feeder is 480V and the other is 208V. But it does not appear that either of these situations apply here. So I would have to say that your suggestion would not meet code. Sorry.
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Hmm...interesting. I think about modular/containerized data centers (http://www.astmodular.com/solutions/family/modular-data-centers_1) that I have done in the past that have sat outside buildings. I definitely remember having an A & B 480V feeders to this data center. It was probable that since it was a data center the feeds did add up to over 2000 amps, but I don't recall even considering that.
 
Have run into this kind of thing a long time ago and we still do it quite often for some applications. In particular grain storage structures. We put the service, motor controllers, all at one location - usually a stand alone structure and run branch circuits to each load from there.

There may be a conveyor or series of conveyors from one structure to the next for material moving to/from a common load/unloading point - which may sometimes also be another separate structure - yet they are all tied together and treated as one operation for the most part they just happen to be pretty large free standing tanks if you want to look at them that way. Put several small tanks under a roof and you don't have as much problem calling it equipment within a structure.
 
jim dungar said:
If the facility has a documented LOTO, per OSHA or NFPA70E, why would that not be acceptable?
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I really can't say one way or the other. While Code uses the term documented safe switching procedure, Code provides no elaboration, leaving qualification to the AHJ's discretion.
 
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