"emergency" generator vs. battery E-lighting 5

[Senselessticker]

Anyone have any long term cost comparisons on emergency generator vs. battery powered emergency lighting and exit signage? This is about a 100K sq. ft. commercial office building (in conceptual design phase). Some folks here are getting concerned over the maintainance/testing cost requirements to keep the generator designated as "emergency" as opposed to "stand by" only.

I'm "guessing" that its cheaper in the long run to just keep the generator up to emergency status and not use battery powered E-lights/signage. Anyone know of literature / study / report that supports such an idea for a similar sized building?

Thanks for any help!

 

[dpc]

If you've ever been in a large group of people who were plunged into total darkness, you probably would not be asking this question. I don't think you are going to be able to eliminate all of the battery-powered emergency lights, no matter how spiffy the generator is.

Wall-packs and battery-powered ballasts are not that expensive. The battery maintenance is a headache, I will grant you that.

But even though an emergency generator is required to start within 10 seconds by Code, the engine is not aware of this Code and these often do fail to start, especially if they are not started and loaded periodically.

I have been involved on projects that used large central battery-power inverters and/or emergency generators for emergency lighting. In every case, they ended up installing self-contained battery-powererd emergency lights due to either: total failure of the central system, or determining that the lag time for a generator start was not acceptable. This is especially true in restrooms, basements, and other areas with no windows.

In terms of cost, I doubt the emergency generator system would be less expensive by the time you factor in the separate raceway systems and panel required, but that's just a guess. The engine-generator has its own maintenance costs (and batteries).

 

[Senselessticker]

DPC - thanks for the post...

building on DPC's post:

Okay...let's say I place some battery packs / battery backed ballast in practical areas, but only as a means of "worse case" E-lighting. If I can manage to keep the generator and emergency lighting system up to Life Safety standards (for code compliance). Is this going to save money vs. relying sololy on battery packs to provide Life Safety E-lighting?

I've done a number or retofit E-lighting jobs for large office buildings using wall packs and emergency ballasts. This is VERY expensive to use these lights to get the average 1 fc required. And....the batterys will need to be replaced every 5 years or so. Any thoughts?

 

[davidbeach]

If you have to meet the building code requirements of 1 fc of egress illumination, and the AHJ actually enforces that requirement by making measurements prior to issuing the certificate of occupancy, you will not rely on unit equipment to provide your egress lighting. You would need far more wall pack "bug-eye" units to get to the point of code compliance than you would want to pay for. Generators could be 25% the cost. The maintenance costs for unit equipment is also far higher than for a central system, battery or generator. A properly maintained engine-generator system can be highly reliable.

 

[dpc]

If this were a hospital, I might agree with davidbeach, but it isn't, so I don't.

In a commercial office building, the odds of anything being properly maintained are very low in my estimation. Also, my experience has been that the 10 seconds or more of waiting in the dark for the generator to start turns out to just be unacceptable to tenants, regardless of the NEC says.

If you have a large number of wall packs or battery ballasts that are not well-maintained and perhaps 25% fail in an outage, you still get 75% of the intended lighting. If the generator or inverter system fails, you get 0% light. Been there and done that.

I've never had a problem with inspectors, 1 fc, and wall-packs + battery ballasts. Maybe I've just been lucky.

Even if you decide to go the emergency generator route, I'd recommend putting wall-packs in restrooms, basements, and.....

the emergency generator room That way, they will have some light while they are trying to get the engine started.

 

[waross]

Do I understand that you presently have a generator and are considering changing to battery packS?
That would change the econommics considerably.
I would suggest that the reliability of the generator will be improved if you arrange a timer to alert you to slow starting on the weekly or monthly exercise timer. Complete failure to start is often preceded by longer and longer cranking times. In conjunction with a slow start alert I suggest NOT using the battery charger. I have found that with a battery charger, the generator will usually start well right up to the day it fails completely. I also experience battery explosions as a failure mode with battery charger equipped gensets. 15% or 20% of the sets that I service have failed to start as a result of battery explosions. I never have a battery explosion with a generator running without a battery charger and the owners often notice the extended cranking times in time to have me replace the battery. I have actually had more "complete failure to start" issues with battery charger equiped sets than on the sets without a battery charger.
I do understand that the code requirements for an emergency status generator may mandate a battery charger but with the 15 or more residential sets that I have installed and service I am not impressed by battery chargers.
My installations are not in the jurisdiction of the NEC or the CEC.
respectfully

 

[BJC]

Has anyone checked LED lamps for this application? Hopefully I've done my last commercial job but I have been reading here and there on LED lamps. I saw a few demos that looked like they would work. If you can get those that put out enought light a couple of car batteries would work fine.
It's a good reason to let a good lighting rep buy you a lunch once in a while.

 

[itsmoked]

Good points BJC and waross.

Very interesting info about the chargers.. I can see it clearly.

Can you guess whether the batteries are exploding due to the sudden huge current draw on a flaky old battery or sparking starter brushes?

I can also understand the cranking problem right up to a battery with decaying capacity until the day the battery is 1AH less than necessary.

As long as exercise puts back the starts.. and the exercise is weekly I would imagine the no charger scheme makes a bunch of sense.

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[Senselessticker]

Waross,

I do not presently have a generator. In fact, the building is still in conceptual design phase. I have been tasked with writing the electrical design criteria for the building. The building is actually going to be the headquarters of the company I work for (a blooming A/E company).

It seems there are very different opinions on this issue. I'm going to dig in deeper and do some more research on the cost comparison. I may actually crunch some numbers on material cost/labor/etc...I'll report my findings here.

Even if I do stick with using an "emergency" generator (as opposed to "standy by"), I plan on placing a few battery packs or ballasts in areas where total darkness is possible.

Many thanks for all the post.

 

[waross]

Hi Keith
Not starter brushes. The starters are too far away. If an explosive hydrogen mixture was to extend to the area of the starter I imagine that the damage would be more extensive than just the battery.
The owner usually doesn't hear the explosion. The sets are located so as to limit noise transmission as much as possible. I have not been able to determine accurately whether the explosion is related to starting or if the battery gets so dry that the charging current can make a "hot spot".
respectfully

 

[itsmoked]

Thanks W.

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[EEJaime]

I find that for many commercial and educational facilities I design, that it is often cost prohibitive for a generator system to be used as a life safety power source. In this size of a facility, I would recommend a small central inverter system to power your emergency loads. One system I use is manufactured by Myers Power Products-

http://www.myerspowerproducts.com

These come in various sizes and can feed all types of lighting loads with zero time delay, (for those HID sources). The costs are reasonable and the equipment is easily maintained and can even e-mail, fax or voice mail maintenance messages, alarm conditions, etc..., and keeps a log of alarms, etc... Several other manufacturer's have similar equipment, Dualite, Prescolite, McPhilben,etc...

 

[davidbeach]

How do you figure a generator system to be cost prohibitive? Battery sources are generally less expensive below 5kW, and generators gain a clear cost advantage above 15kW. In the 5-15kW range there can be many things that push one project one way or the other.

 

[PaulRuther]

Hi Senslessticker, Thank you for the question about generators and battery back-up systems. After reading all of the posts above, its seems that "battery-101" class has not been taken. The VRLA battery manufacturers test their product at 77 degree F. For every 10 degrees about that mark the battery's life span is cut in half! The inside temperature of the "bug-eye" and the ballast type is usually 10 degrees and sometimes as much as 30 degrees more than the ambient temperature. That is why there is a failure rate of 25 percent to 50 percent with these systems.

The other cost issue with the wall mounted "bug-eye" and battery ballast systems is that they have to be checked every 30 days for 10 seconds and once a year for the full 90 minutes according to NFPA 101. This leads to a high cost of ownership, as constant checking and replacement of failed units keeps the guys in the maintenance department busy.

In the centralized system, the same holds true concerning the temperature of the batteries. That is why newer UPS technology has included this as part of the alarm systems. One other note though, your off the hook for the 30 day testing per code requirement but not the annual.

Just bare this in mind, it was well maintained UPS's that kept the stair well lights on in both of the Twin Towers that made a safe egress possible for all but the 3000.

 

[RAF7]

This thread brings up a pet peeve of mine. The whole emergency lighting system seems to be a lose/lose issue. (Yeah, I'm in a bad mood!)


Individual emergency lights:

They don't last long, are a pain to maintain, and the NEC, etc. maintenance/verification requirements are onerous and very few building owners actually do them.

They are relatively inexpensive and tie in to the nearest light circuit. They do provide emergency lighting (when they work) for power outages in their area. The whole building doesn’t have to loose power. You can turn fluorescent emergency fixtures off and on but they will go on when the sensing leg looses power. So you don’t have to have the emergency lights on 24/7, an energy plus. But, fluorescent emergency lighting is a real pain to test and maintain - especially lay-in fixtures.

What’s the realistic life time? Ambient temperature has a big effect.

For small installations, they are essentially the only option.



Emergency Generators:

Expensive first cost (generator, transfer switch, dedicated, isolated feeders to each fixture) but you definitely avoid the monthly testing bit for battery lights. You just have to be sure the generator is properly maintained, etc. One failure and the whole building is in the dark! Even if everything works like it should, as others mentioned, 10 sec in the dark on the throne or in a crowded store is an eternity!

Dedicated raceways are required. The whole building has to loose power before it comes on so if power is lost on the fifth floor, the fifth floor is in the dark - unless you provide some form of sensing for each floor, etc. - $$$.

Unless I missed something, you have to leave the emergency lights on 24/7 since you can’t effectively switch them. Not the best in energy conservation. I guess you can do some form of relay transfer at each light, but again that's $$$, complications, etc. One might argue that switching them is ok since you can’t occupy an area without lights, but I don’t see that as meeting code.


Inverters:

About the same issues as generators, just lots more batteries. At least you don’t have an engine to deal with and the lights will come on quickly.


Conclusion?

Is there one? We have to have emergency lighting, but it sure has lots of negatives for keeping them up to snuff.


“Rant off”

 

[mohpower]

Hi,
if you are aware of the 10 seconds in the dark and you do want to feel the utility power failure then you could go with a Euro-Diesel’s No-Break KS® dynamic UPS systems, . I installed one system already for Sheraton hotel and it works perfectly. for more inforamtion on this system you can check the following link

http://www.euro-diesel.com/total_technical.html

take care

http://www.ierltd.com

 

[ScottyUK]

Are Eurodiesel still trading under that name? I thought they had been absorbed into GE? I've worked with their products and they are very impressive, as are the similar designs from Anton Pillar.

The big rotary UPS units aren't available below about 300kVA, so probably not of any direct relevance to this thread.


----------------------------------

I don't suffer from insanity. I enjoy it...

 

[mohpower]

Hi ScottyUK

yes Euro-diesel rotary UPS is bought by GE.

regards

 

[rawelk]

Although it isn't a perfect solution to the "10 seconds in darkness" issue, a fairly cheap work-around is possible for existing emergency generator systems. In my case we use metal halide lighting, and even a momentary voltage drop-out extinguishes the arc. This was double-trouble, because if utility voltage came back before the generator fired up (the generator control minimum outage was 10 seconds) it never would.

I connected a 120V coil relay to monitor line voltage, and used a set of NC contact from it in a latching circuit using a 12 VDC coil relay connected to the starter battery. If voltage drops long enough to kill the 120V relay (typically 35 to 40 milliseconds), then it latches on the 12VDC relay, which in turn signals the generator to run.

This isn't a perfect solution. MH lamps drop out anywhere from 1/2 to a full AC cycle, so theres a 'dead spot' window of maybe 20 to 25 ms, but, in practice, I've found it effective approximately 95% of the time.

 

[RonShap]

This is how I handle the HID arcs now

http://www.bodine.com/products/arckeeper.html

I am a proponent of both the generator and batteries. Most folks don't want to lose that much usable space to install a gen.