Emergency Lighting - Alternatives?

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Ragin Cajun

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Upstate S.C.
There have been several threads on emergency lighting lately. I have a question regarding relative costs between the two main alternatives of providing emergency lighting power ? batteries vs generator.

Alt #1: Vanilla battery packs, bug eyes, exit signs, fluorescent with battery back-up, etc. This has the big advantage of lowest installed cost and simplicity.

Alt #2: Building has an emergency generator to maintain critical computer, process, etc. systems. From what I see Art 700 (life safety) requires 10 second start, independent transfer switch, dedicated conduits, ID of all boxes and enclosures, etc. Does this ?identification? include junction boxes, LB's, etc? What about the fixtures themselves? One now has a potentially large amount of dedicated emergency conduits running all over the building with a significant first cost plus the second transfer switch, an emergency panelboard, etc. One does offset these costs by not having to buy battery units.

Note, even when a building does NOT need a generator, does a generator for emergency lighting ever ?pay off?? You have to consider the maintenance costs of having a generator vs battery packs. While there are costs of replacing battery packs or their batteries at some point, a generator does have a significant maintenance cost as well.

Obviously, higher buildings will have a generator for the elevator, if nothing else.


I see the cost for Alt #2 as very high and generally the client will balk.


Often the egress emergency lighting is on 24/7. My experience has been these lamps go first and seldom are replaced in a "timely manner." There is a "transfer device" that can be installed in fixtures that allows the fixtures to be switched on and off via the normal power circuit but transfers to emergency source when normal power fails and turns the lights on. But, how will the AHJ take to these? Plus, they are yet another additional cost.

How do you see the overall cost difference between the two alternates falling out? Obviously, a very large building would likely be cost effective with the generator. I am really concerned with small and medium sized buildings.

Any thoughts on this issue will be appreciated!


RC
 
Okay, I've hesitated from obfuscating this thread several times -- time to just dive in.

Based on my experience in Katrina Land, one of the obstacles to a less pricey emergency power solution in a residential environment is the original layout of the electrical circuits. My experience is that people can live without just about anything but general purpose lighting for hours (or weeks ...) on end, but that a lack of lighting is a major obstacle to getting on with life.

If I were putting an emergency power solution in a residence, and I were able to separate all of the habitable space lighting from everything else, I'd go that route, then go with a much smaller backup solution. The only other circuit that's essential would be refrigeration. So a 20A circuit for, say, family room, bedroom, bathroom and kitchen lighting, plus a convenience outlet for charging cell phones, then a 20A circuit for refrigeration. At that point, a PV solution becomes practical.

When I've gone into a building in Katrina Land that's been the priority -- ranges, hot water heaters, and a bazillion receptacles can all wait. But habitable room lighting, power to a fridge, and a place to recharge cell phones is high on the To-Do list.
 
Ragin

Ragin

My two cents..

In all the buildings around me,, mostly small warehouse space (10,000sqf warehouse 3,000sqf office) have all the same systems. Vanilla battery packs for the lighting and 15min battery backups for the computer systems. The reason for this is simple.. If the power goes out in an office building people just want to leave. Work rarely gets done, people are worried about there own homes, family etc. I would design a safe system to allow them to exit the building safely and shut down there computers without losing work. The cost is always in the budget and you create something useful.
 
RC,

Thought I would mention that, in many cases the battery back-up fixtures

are still required even if a generator is installed.

If a c.b. trips or a panel is overloaded and trips a feeder c.b. the emg. lts.

will still be needed.
 
benaround said:
RC,

Thought I would mention that, in many cases the battery back-up fixtures

are still required even if a generator is installed.

If a c.b. trips or a panel is overloaded and trips a feeder c.b. the emg. lts.

will still be needed.
Click to expand...


I have never seen or heard of a code requiring that. Is it possibly a local code?

Certainly a good design but not a general code requirement.
 
Alt #2: Building has an emergency generator to maintain critical computer, process, etc. systems. From what I see Art 700 (life safety) requires 10 second start, independent transfer switch, dedicated conduits, ID of all boxes and enclosures, etc.
Click to expand...

Keep in mind the generator itself, the battery charger, the ATS etc. must all be listed for emergency use as opposed to standby use.


Does this ?identification? include junction boxes, LB's, etc?
Click to expand...

We don't generally identify conduit bodies.

What about the fixtures themselves?
Click to expand...

Almost never, maybe we should be.


Note, even when a building does NOT need a generator, does a generator for emergency lighting ever ?pay off??
Click to expand...

I doubt it, keeping the generators serviced is expensive. You can buy a lot of batteries for the cost of maintaining a good sized emergency generator.


Often the egress emergency lighting is on 24/7. My experience has been these lamps go first and seldom are replaced in a "timely manner." There is a "transfer device" that can be installed in fixtures that allows the fixtures to be switched on and off via the normal power circuit but transfers to emergency source when normal power fails and turns the lights on. But, how will the AHJ take to these? Plus, they are yet another additional cost
Click to expand...


We shut these down all the time, at its most basic we use normally closed contactors with a control circuit not supplied by the emergency system

One of the large department store chains shuts down everything at night, emergency lights, exit lights, receptacle outlets other than the office.

The lights will come on due to a fire alarm trip or a power failure.
 
Bob,

I'm not sure if it is a local code, but I've been required to use battery back-

up even when the gen. took care of the entire electrical system. But since

you mentioned it I started looking thru 700 and 700.17 in particular states

that ( to me ) if the emg lgt. circuit is interupted something must keep the

area lit up. another article said 'weather from outside of or within the building'

refering to the reason for the outage. What you think?
 
I have to agree with Bob, battery backed-up lights are NOT required with a generator. We are to protect basically for one failure, not multiple failures.
 
iwire said:
We shut these down all the time, at its most basic we use normally closed contactors with a control circuit not supplied by the emergency system

One of the large department store chains shuts down everything at night, emergency lights, exit lights, receptacle outlets other than the office.

The lights will come on due to a fire alarm trip or a power failure.
Click to expand...
I did that for a large warehouse and also a hazardous waste storage facility. I'm glad to hear others think that a generator for just emergency lights is an expensive proposition and not likely to pay off. Any others with your experiences?? Thanks, RC
 
Don't forget about the middleground solution, a central inverter. Also, lighting supplied by a generator or inverter tends to provide MUCH better illumination than a bugeye or integral battery in a fluorescent fixture.
 
OK, nobody ever talks about the maintenance (not much) and eventual replacement of the batteries in self contained units. This isn't so bad in bug eyes or exit signs, but what aobut emergency ballasts? You have to replace the whole ballast, at ~$120 in materials alone. The factory says they will last about 8 years, anybody have real data on how long an emergency ballast will last?

Not that keeping a generator around is cheap either!

Central invertors look like a steal if you factor in a 100% replacement of units in a good sized building.
 
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