Art 700 - Emergency Generators

[Ragin Cajun]

We are designing the electrical for an apartment building that has 4 levels. The elevator is thus required to be on a generator.

Since we have a generator, we plan to put all the egress lighting, etc. on it as well.

In looking over NFPA 110, it gives various "Class", "Type", and "Level" requirements but doesn't explain which one should use. I'm not so much concerned with the Class as egress lighting must be present within 10 seconds and needs a minimum of 90 minutes operation.

The "Level" is another matter:

4.4* Level.
This standard recognizes two levels of equipment installation, performance, and maintenance.
4.4.1* Level 1 systems shall be installed when failure of the equipment to perform could result in loss of human life or serious injuries.
4.4.2* Level 2 systems shall be installed when failure of the EPSS to perform is less critical to human life and safety and where the authority having jurisdiction shall permit a higher degree of flexibility than that provided by a Level 1 system.


Later under energy sources is the following:

5.1 Energy Sources.
5.1.1* The following energy sources shall be permitted to be used for the emergency power supply (EPS):
(1)* Liquid petroleum products at atmospheric pressure
(2) Liquefied petroleum gas (liquid or vapor withdrawal)
(3) Natural or synthetic gas
Exception:
For Level 1 installations in locations where the probability of interruption of off-site fuel supplies is high, on-site storage of an alternate energy source sufficient to allow full output of the EPSS to be delivered for the class specified shall be required, with the provision for automatic transfer from the primary energy source to the alternate energy source.

Also, location is an issue:

7.2 Location.
7.2.1 The EPS shall be installed in a separate room for Level 1 installations. EPSS equipment shall be permitted to be installed in this room.

I understand this to relate to the generator proper. It will be located outside the building (obviously).

and

7.2.2* Level 1 EPSS equipment shall not be installed in the same room with the normal service equipment, where the service equipment is rated over 150 volts to ground and equal to or greater than 1000 amperes.

OK here as we are using 120/208V

7.2.3* The rooms, shelters, or separate buildings housing Level 1 or Level 2 EPSS equipment shall be designed and located to minimize the damage from flooding, including that caused by the following:
(1) Flooding resulting from fire fighting
(2) Sewer water backup
(3) Similar disasters or occurrences

We plan to install everything above grade.


Any of you run into this lately? In the past if natural gas was available at the site, using it was a no brainier. Now, unless it can be a Level 2 installation, on-site storage of fuel is required.

Is the egress lighting, elevator, etc. Level 1 or 2?? I know in a hospital it's Level 1, but what about an apartment building? Big difference in installation costs, etc.

The location of this apartment is Charleston, SC. so we will need to address seismic issues in mounting the equipment.

Any help is appreciated.

RC

 

[dbuckley]

In the past if natural gas was available at the site, using it was a no brainier. Now, unless it can be a Level 2 installation, on-site storage of fuel is required.

Thats not what it says -

For Level 1 installations in locations where the probability of interruption of off-site fuel supplies is high, on-site storage of an alternate energy source sufficient to allow full output of the EPSS to be delivered for the class specified shall be required, with the provision for automatic transfer from the primary energy source to the alternate energy source.

So, if you believe that the gas will continue to flow for 90 minutes after you lose power, then you can use gas.

Note this isn't quite a "no-brainer" - when gas is the emergency supply fuel you always need to consider the possibility of gas loss. I agree that the answer will pretty much always be that gas operates independently of electricity for the required time window. However, if gas and elec are both distributed undergroud in close proximity, one good backhoe shot may take both out...

 

[Volta]

I agree with Dbuckley, and feel that the loss of power to the system would be "less critical to human life and safety" than the "loss of human life or serious injuries".

But only allowed with the agreement of the AHJ: "and where the authority having jurisdiction shall permit a higher degree of flexibility than that provided by a Level 1 system".

 

[steve66]

I basically agree with the first two comments. I believe emergency lighting is almost always Level 1.

I don't think you could use natural gas as the generator source in San Francisco, since an earthquake could easily take out both gas and electricity.

But in areas where the chances of an earthquake is significantly less, I think it's basically the AHJ's decicison if they will allow natural gas.

I'm not sure what code is requireing you to put the elevator on the generator.

Steve