Emergency and Normal Power

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Jimmy7

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Boston, MA
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Electrician
Could you help me with understanding the separation of Emergency and Normal power. I seem to be getting conflicting information on this topic. For example we have a job where we are changing out the main switchboard at a college. In order to get this done they're going to put on an electrical room as an addition.

The proposed drawings show the following equipment for this electric room addition as the following:

4000 AMP Switchboard 480/277 V, a Generator Switchboard, Emergency Panel and ATS, Optional Standby Panel and ATS, Legally Required Panel and ATS, and two normal 480/277 volt panels, and one normal 208/120 volt two tub panel and transformer.

I was always under the impression that you couldn't have normal and emergency power share the same room.

Doesn't NFPA 110 7.2.3 prohibit this?

NFPA 110 [FONT=arial, sans-serif]7.2.3 which states "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"[/FONT]
 
I think it's a good bet that NFPA 110 will apply.

There are great opportunities for confusion in all NFPA documents, and 110 is no exception. To clarify, then, the Emergency Power Supply (EPS) is essentially the generator. The Emergency Power Supply System (EPSS) is the generator and all conductors, controls, and other components up to the load terminals of the "level 1" (which is to say article 700 in NEC language) ATS. Therefore, the generator and the ATS cannot be in the same room as the normal system components. However, the generator switchboard and emergency panel can be in the same room as the normal system components, as these are downstream of the article 700 ATS. I usually try to handle this by putting the generator outside and carving out a small room (with a 1 hour barrier) for the ATS.
 
charlie b said:
I think it's a good bet that NFPA 110 will apply.

There are great opportunities for confusion in all NFPA documents, and 110 is no exception. To clarify, then, the Emergency Power Supply (EPS) is essentially the generator. The Emergency Power Supply System (EPSS) is the generator and all conductors, controls, and other components up to the load terminals of the "level 1" (which is to say article 700 in NEC language) ATS. Therefore, the generator and the ATS cannot be in the same room as the normal system components. However, the generator switchboard and emergency panel can be in the same room as the normal system components, as these are downstream of the article 700 ATS. I usually try to handle this by putting the generator outside and carving out a small room (with a 1 hour barrier) for the ATS.
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IMO the NFPA 110 restrictions only apply to service equipment. If the switchboard is not service equipment, that section would not apply.
 
The drawing refers to it as a "Main Switch Board "MSB" 4000A 480/277V 3-PH/4W" , and the only thing upstream is a utility transformer.
 
In MA you need a separate room 2hr Fire rated for the emergency system.
See the MA amendments.
 
packersparky said:
IMO the NFPA 110 restrictions only apply to service equipment. If the switchboard is not service equipment, that section would not apply.
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I'd disagree with that, although I give you it isn't stated very clearly in the code, and I think we have decided this is service equipment anyway.

Anyhow, I believe the intent is to apply to all equipment supplied from the normal service that is above 1000 amps and 150 volts to ground.

Its kind of the difference between saying "normal service" equipment and saying normal "service equipment".

It reads totally different if you group the word service and normal than it does if you group the word normal with equipment.

Maybe its easier to explain using dashes:

I read it as normal-service equipment, and you read it as normal service-equipment.
 
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