Generator and multiple buildings
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bphgravity
Senior Member
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- Florida
What Sketch?
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- Lockport, IL
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- Semi-Retired Electrical Engineer
This is another interesting question. It is similar to the question posted here:
http://www.mikeholt.com/code_forum/showthread.php?t=79292
But this question differs from the other question in one key way. In this case, the second power supply is for an emergency circuit. You will note that both 225 and 230 include emergency circuits in the list of acceptable reasons for having two feeders or for having two services.
The two questions are similar in this way: In one case, we are looking at one service and one branch circuit. In the other case, we are looking at one service and one feeder. So in neither case does 225 have the answer, and in neither case does 230 have the answer.
If I can find my list of issues that were possible submittals for the 2011 NEC, I?ll add this one to the list.
http://www.mikeholt.com/code_forum/showthread.php?t=79292
But this question differs from the other question in one key way. In this case, the second power supply is for an emergency circuit. You will note that both 225 and 230 include emergency circuits in the list of acceptable reasons for having two feeders or for having two services.
The two questions are similar in this way: In one case, we are looking at one service and one branch circuit. In the other case, we are looking at one service and one feeder. So in neither case does 225 have the answer, and in neither case does 230 have the answer.
If I can find my list of issues that were possible submittals for the 2011 NEC, I?ll add this one to the list.
My first reaction is that the ground from the new building is tied to the second building. They are from seperate utility transformers.
The voltage drop on the neutral in from the old building won't be the same as the voltage drop on the new building.
I was of the opinion to set a transformer at the new building and derive a new neutral and ground for the new building.
thanks
The voltage drop on the neutral in from the old building won't be the same as the voltage drop on the new building.
I was of the opinion to set a transformer at the new building and derive a new neutral and ground for the new building.
thanks
ramdiesel3500
Senior Member
- Location
- Bloomington IN
What about using a 4-pole transfer switch in the second building to create a separately derived system?
Charlie:
In my opinion, this is allowed, and I think it s done all the time. Don't you agree that if the NEC doesn't prohibit it, then it is allowed? (I think I might have even learned that from you
)
However, I am concerned when the original question says "Building B wants a life safety circuit". Life safety circuits are required. The only equipment you can put on a life safety circuit are loads that are legally required. If they just have some lights in building B that they would like to run during a power outage, thats a whole new ballgame.
Steve
In my opinion, this is allowed, and I think it s done all the time. Don't you agree that if the NEC doesn't prohibit it, then it is allowed? (I think I might have even learned that from you
)However, I am concerned when the original question says "Building B wants a life safety circuit". Life safety circuits are required. The only equipment you can put on a life safety circuit are loads that are legally required. If they just have some lights in building B that they would like to run during a power outage, thats a whole new ballgame.
Steve
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