Emergency Vs. Standby Genterators

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new_ee

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Egress illumination must be provided with emergency power back up. I have a few points of confusion here.

1) Can I use a generator for emergency egress illumination?

NFPA 101 (7.?) sounds like the emergency egress illumniation must also come on if a breaker or fuse is tripped. The generator would not come on if the branch circuit breaker supplying the egress illumniation is tripped. So I'm not so sure that using a only generator would meet that requirement. I think I need stored engery back up(battery).

2) Whats the difference between an emergency and standby generator (either required or not)? I've heard that emergency generators require two fuel sources but so far haven't located that in any applicable codes.

3) If I can use a generator for egress illumination does it automatically become an "emergency" generator vs. a "standby"? Are there any ramifications to that.


A little background information. This is for an apartment complex. A generator has been requested. I'm not sure if its legally required or optional (I'm having trouble locating that in applicable codes as well). I was thiking of putting some of the normal lighting on a circuit that could be powered by the generator in case of a power failure. Then I came across the NFPA 101 requirement that egress illumination should be engaged if a breaker or fuse trips. So now I'm confused on whether I will need to have battery backup egress illumination as well.
 
Re: Emergency Vs. Standby Genterators

1)

An emergency generator is usually an acceptable method of providing emergency lighting - provided it meets all the other requirements (like listed for use as an emergency source, and tested per the NFPA schedule). But I also know my local AHJ requires the addition of battery powered units in stairwells. So double check with your AHJ.

I think your egress lights only have to come on when a main circuit breaker trips. I have never had to monitor every branch circuit for loss of power. If a branch circuit trips, a limited area is only in the dark. If you are concerned about it, use two branch circuits to light the hall.

2 & 3)If it is an emergency generator, you have to have any optional loads (things the owner wants on the generator, but aren't required by law) on another transfer switch. That's the code phrase about being "completely independent". And I think the optional transfer switch needs load shedding build in.

I don't know of any requirement for 2 sources of fuel, but using natural gas from the utility may not sufice. The fuel source may have to be on site.

Steve
 
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