Question re: 225 Part II

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sandsnow

sandsnow

Senior Member
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Southern California
We have apartments and condos in town that are built to surround a parking structure. They are two seperate buildings structurally, each will stand without the other. The seperation between the two structures is mere inches.

These are two buildings and the rules in 225 Part II apply.

The question comes in a proposal by the designer. They want to put the service equipment in the parking structure and run feeders to each unit from there.

A violation of the the rules in 225 Part II.

My question is:
Have you seen this specifically allowed anywhere?

If so what was the AHJ justification?

To the casual observer and even emergency response personel, this is one big building.

Any thoughts???

Thanks
 
Re: Question re: 225 Part II

sandsnow said:
They want to . . . run feeders to each unit from there.
Click to expand...
Did you use the plural "feeders" because there are two buildings, or because each building is intended to get more than one feeder? The former is OK, the later violates 225.30.
 
Sorry about the confusion.

Service in parking garage.
Apartment building surrounds garage, seperated by inches.
They are two bldgs. To the casual observer, they appear as one.
They are connected by architecural stuff such as flashing
A feeder for each apartment will be run from service in garage into apartment bldg.

A violation of 225.30. More than one feeder to the second bldg. 225.30(B)(1) applies, but it would be a simple matter to design an electrical room into the apartment bldg.

The designer claims he has done this elsewhere, so I am asking if anyone has heard of such a thing.

thanks again
 
Larry
Are there 2 different (codewise) buildings for the apartment buildings and one structure - for the parking?

Lets see if I have this straight.
There will be a service to the parking structure (PS). Then the service in the PS will supply one feeder to each apartment building. The PS and the apartment buildings are on the same property/premises.

If this is so, 225.30 would apply, and I do not see a violation.
 
pierre said:
Larry
Are there 2 different (codewise) buildings for the apartment buildings and one structure - for the parking?

They are two bldgs. They are structurally independent

Lets see if I have this straight.
There will be a service to the parking structure (PS). Then the service in the PS will supply one feeder to each apartment building. The PS and the apartment buildings are on the same property/premises.

Hmmm, maybe I missed something? The building looks like this:
AAAAAA
AAAAAA
AAPPPP
AAPPPP
AAPPPP
AAAAAA
AAAAAA

So you see the parking structure is in the middle. Both buildings are on the same level.

If this is so, 225.30 would apply, and I do not see a violation.
Click to expand...
 
Larry
That AAAPPP thing was very clever. At first I thought it was some coded thing I should know, then I realized it was the apartment building and PS.

Are they installing the service in the PS, and one feed to the Apartments?
 
Pierre he has two feeders from 'P' to 'A'

Larry is the total of the two feeders in excess of 2000 amps?

225.30(C)?

I recall one large building we did that had seven feeders running into it but each one was 3000 amps at 480.
 
There will be about 48 feeders from the PS to the apart's. If the bdg's were seperated by 20 feet, it would be a clear violation. These are only seperated by a matter of inches.

Just wondering if anybody has seen this??

I heard this type of bldg was originated in Texas.
 
sandsnow said:
They are connected by architecural stuff such as flashing
Click to expand...
That is enough for me to call it "one building." I think you accept the proposed electrical layout, and walk away happy.
 
Is there some way that the structural steel could be connected between the two separate buildings. I do not see how flashing could make one building connected to the other as far as code is considered.
IMHO this is two different structures as explained.
This will make a difference as to how the Grounding Electrode System will be installed/ Equipment Grounding as well.

What size are the feeders to the apartment building?
 
The feeders are 100amp.

Charlie
Our Deputy Building Official will make the final call. This will affect numerous projects here in the future. Although this one might be an easy call to "see" as "One Building", we are trying to create an interpretation that can be applied in the future. Thus my solicitation of input.

Factors or conditions would include:
Distance apart
Connection by flashings etc.
Number of common sides
 
Then my only remaining suggestion is that you keep focus on the question, "What is the problem that we are trying to solve?" Specifically, what is the problem that the authors of the NEC were trying to prevent, when they put in the restrictions against multiple feeders from one building to another? I believe it has to do with fire fighting. If you need to turn off power to a building, in order to safely enter it, then it helps if you don't have to throw too many breakers or go to more than one location to find the breakers. In your case, since you can go to one spot in one building (i.e., the parking area), and throw one breaker (main service disconnect) to turn off all power to the other building, then the intent of the code may be satisfied.

Good luck with this one.
 
So each apt feed is coming from garage ?. If the bdlg's are not structurly connected,who would consider these bdlg's as one. I would run 1 set of feeders to each bdlg's electrical room,then feed each apt from there. If there is fire the fire dept will enter the front lobby and will be happy to see a door marked electrical room. :D
 
My guess is that the entire site will share a common ufer. With distributed buildings, the worst being using old grounded delta systems, huge ground currents can exist. The model of a ship is helpful to imagine the situation. My choice for this type of construction would have a single point grounding system for the entire site. Although I feel silly mentioning it, the 'distribution point' and 'equipotential plane' references in article 547 are what I've seen work best.
At one site in Oxnard with typical daytime loads in the 1.8 meg range and several transformers up to 1/3 mile from each other, an RMS meter between 480 and 208 receptacle grounds would show up to 20 volts before applying these rules. ESD grounding issues disappeared at the same time.
So it 'looks like one building must be one building'
 
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