Whole Building Emergency Generator

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kelli

Member
Location
Austin
Hello;

I am designing a Fire Station, and they want the entire building on the Natural Gas Generator. I am having a difficult time figuring out how to draw the one-line diagram as I don't understand if it would need a transfer switch and if so, why? I have special night lighting and other emergency entities (receptacles etc.) but since everything is on a Generator anyway.. How is that going to look? Thanks!
 

iwire

Moderator
Staff member
Location
Massachusetts
This gets a bit tricky as there is generally no such thing as a whole building emergency generator.

Typically a generator that picks up the entire building load via one transfer switch would be an optional standby generator.

The terms become important, and you should read all of articles 700, 701 and 702. They cover Emergency, Legally Required and Optional Standby systems respectively.


Most likely you will have a combination of article 700 and 702 which means at least two transfer switches would be needed.
 

iwire

Moderator
Staff member
Location
Massachusetts
For me the big items to understand are that only very specific loads can be connected to the emergency system and all the wiring between the generator and those specific loads must be kept separate from the 'normal' wiring. Separate panels, raceways cables transfer switches etc. There are some exceptions out of necessity.

On the other hand the optional standby loads can be run with the normal wiring.
 

kelli

Member
Location
Austin
I believe I understand.. so the one-line would look like this (ignoring sizing please, and the obvious quickness with which I drew it) : Captureoneline.JPG

I cannot figure out how to make the jpg so that it is legible. Can I get some help? Or if you click it, does it 'open' for you? Argh.. Thanks!

Kelli
 

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ceb58

Senior Member
Location
Raeford, NC
I believe I understand.. so the one-line would look like this (ignoring sizing please, and the obvious quickness with which I drew it) : View attachment 12410

I cannot figure out how to make the jpg so that it is legible. Can I get some help? Or if you click it, does it 'open' for you? Argh.. Thanks!

Kelli

Why are you drawing an ATS in between the utility transformers and generator? What type system has the AHJ deemed this to be emergency or optional stand by? Have you done a load calculation? If the fire department has the drawing/design done by an EE they can apply to FEMA for a grant to pay for the generator as long as they use the building as a shelter in an emergency/ disaster situation.
 

kelli

Member
Location
Austin
I understand.. I drew it incorrectly because I was hurrying. I just don't see how it is 'normal', and 'emergency' separately if they both come out of the generator. I am a designer working under an Engineer who doesn't want me to 'worry' about it, but it is my project and the Fire Station Architect is telling me that they want the entire building on Generator. I will do a load calc today, but the ultimate decision on how it gets designed is not going to be mine, as I am not the person signing off on it. i don't believe it would qualify for the FEMA benefit, but I will check into it as we are in a hurricane and tornado area. Any help is greatly appreciated!

Kelli
 

GoldDigger

Moderator
Staff member
Location
Placerville, CA, USA
Occupation
Retired PV System Designer
I understand.. I drew it incorrectly because I was hurrying. I just don't see how it is 'normal', and 'emergency' separately if they both come out of the generator. I am a designer working under an Engineer who doesn't want me to 'worry' about it, but it is my project and the Fire Station Architect is telling me that they want the entire building on Generator. I will do a load calc today, but the ultimate decision on how it gets designed is not going to be mine, as I am not the person signing off on it. i don't believe it would qualify for the FEMA benefit, but I will check into it as we are in a hurricane and tornado area. Any help is greatly appreciated!

Kelli
Simple: The two sets of wires separate at the generator. If there is OCPD at the generator st all it must be separate OCPDs for the two branches.
Also two transfer switches of course.
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
Does the generator really need to supply Article 700 loads? I would expect that the only Article 700 loads would be exit lights and emergency lights. It would probably be a lot cheaper to use "unit" equipment for these loads and a single transfer switch for the complete building load.
 

mgookin

Senior Member
Location
Fort Myers, FL
Does the NEC define what an essential facility is? Or does it defer to the building code?

Under the building code a fire station is an essential facility expected to function post disaster. Not sure what perils they have there but not having POCO supply should be expected.

And what happens when that natty gas utility is not supplying?

No POCO & no natty gas = no fire station operating?
 

kelli

Member
Location
Austin
So, When you say 'Unit' loads, are you meaning a panel that has unswitched lighting loads fed directly from the step-down transformer? That still won't get them the generator feed that they want. I don't understand. I would like to suggest a scenerio that saves them money, but I am still trying to figure it out. I really appreciate all in-put!

Kelli
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
Does the NEC define what an essential facility is? Or does it defer to the building code?

Under the building code a fire station is an essential facility expected to function post disaster. Not sure what perils they have there but not having POCO supply should be expected.

And what happens when that natty gas utility is not supplying?

No POCO & no natty gas = no fire station operating?
Are you saying the building code rules trigger the application of Article 708, for a fire station?
 

kelli

Member
Location
Austin
Does the NEC define what an essential facility is? Or does it defer to the building code?

Under the building code a fire station is an essential facility expected to function post disaster. Not sure what perils they have there but not having POCO supply should be expected.

And what happens when that natty gas utility is not supplying?

No POCO & no natty gas = no fire station operating?


You are correct and have an important point. I will let you know how it shakes out. I am trying to do the best design, but my hands are tied as far as some of the things that go out. I pray it is all to code. It will be up to the EE who signs it.

Kelli
 

mgookin

Senior Member
Location
Fort Myers, FL
Are you saying the building code rules trigger the application of Article 708, for a fire station?

I'm not saying it does or does not (I'm out of the business now). I raised the question.

I know here when we build police & fire stations, jails, hospitals, primary communications facilities, etc. they are essential facilities built to more stringent factors.

The EE of record needs to figure that one out as well as local & state requirements, client specifications, etc.
 

69gp

Senior Member
Location
MA
Does the NEC define what an essential facility is? Or does it defer to the building code?

Under the building code a fire station is an essential facility expected to function post disaster. Not sure what perils they have there but not having POCO supply should be expected.

And what happens when that natty gas utility is not supplying?

No POCO & no natty gas = no fire station operating?


You are right about the building be able to function post disaster. Another item that needs to be addressed here is that the generator needs to run stand alone. Disaster could involve a loss of natural gas putting the building out of service. think you will need a diesel.
 

69gp

Senior Member
Location
MA
One generator could be used with 2 ATS. First one to come online would be all the emergency loads and the 2nd one would come on after a predetermined time. First ATS needs to be in its own room set up as emergency.
 

iwire

Moderator
Staff member
Location
Massachusetts
One generator could be used with 2 ATS. First one to come online would be all the emergency loads and the 2nd one would come on after a predetermined time. First ATS needs to be in its own room set up as emergency.

The own room thing is just a Massachessttes rule.
 

tom baker

First Chief Moderator
Staff member
There is another standard you should look at, NFPA 110 Emergency and Standby power. Natural gas is not allowed for an emergency generator.. Of course NFPA 110 only applies if it has been adopted by your local agency, fire dept, building dept, etc
 

ceb58

Senior Member
Location
Raeford, NC
There is another standard you should look at, NFPA 110 Emergency and Standby power. Natural gas is not allowed for an emergency generator.. Of course NFPA 110 only applies if it has been adopted by your local agency, fire dept, building dept, etc

The one I installed for a fire department was duel fuel. Natural over LP. You could cut the natural gas valve off and the generator would never miss a beat.
 
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