So, after having to deal with the ensuing power outage from a plane flying into some power lines and killing an exec and two employees from Tesla Motors, I've been tasked with disaster preparedness at our company.
The outage exposed many weak points in our emergency infrastructure. The biggest of all, the lack of emergency lighting - and in places equipped with emergency lighting , the lack of functional lighting.
One of the requirements is for lighting to last longer than 90 minutes, but in general, we'd prefer something that lasts days and possibly weeks if it supports motion detection.
Imagine 2-4x Nichia NS6W083B (like the ones in the Rayovac SE3DLN Sportsman Extreme Lantern) with a 12v7AH SLA running regulated. It would last an entire week!
So yes, a little help finding something like this would uber..
superbrightleds.com sells WLEDB-CWHP4-D-6V and WLED-CWHP6-D-6V designed to replace the incandescent in an ordinary 6V emergency lighting fixture. Options such as that may broaden your options looking for motion-sensing etc fixtures; just toss the incandescent bulbs that they'll come with.
I guess having a weeks worth of battery lighting must depend on the business you run... if you need a lot of computers, you're going to need a generator anyway so you might as well run some lights off it too.
From personal experience, I have pretty much observed the same 90 min. run time on emergency lighting. We had a power outage at work and about half of the emergency lights didn't even work.
The battery in a UPS for computers last about 5 years even if they're not used. I test my UPS's once a year and time how long they last using two 100 watt light bulbs as a load. That's about 2/3 of full rated power. Emergency lights should follow the same 5 year cycle since they also use a SLA battery. You don't want to get caught with your
Most ready made emergency lights are cheaply made, since no one really wants to buy them except when required by law, and then they select the cheapest available.
The run time of an emergency light can be increased by use of LEDs instead of incandesent bulbs.
Remember though that modifying the fixture by fitting different bulbs probably voids the UL listing. No problem in your home, but in a workplace ?
Also in most emergency lights, the lamp is connected to the battery via a relay, and the relay coil is energised from the battery.
The current drawn by the relay coil will discharge the battery in a day or so, no matter how small the lamp current will be.
Also some emergency lights pass a small current through the lamp filament at all times, to prove that the lamp is sound and will work when called on.
This wont work with an lLED and may cause the "mains healthy" pilot lamp to go out, even when all is well.
A moderatly extended run time can be achieved by useing lower wattage bulbs (install larger or additional fixtures to compensate for the reduced output), or in some cases by fitting a larger battery.
For run times of days though, a custom made fixture will be needed.
It might be simpler to use standard 90 minute emergency fixtures, and to provide additional, non automatic LED lighting that uses alkaline D cells, and is turned on when required.
This would ensure that the 90 minute fixtures are standard types and are compliant with all codes and regulations.
4 alkaline D cells will power a single 300ma LED for about 60 hours. Spare cells are easily stocked, and the ones in the fixtures can be replaced at little cost every year or two.
They use a 18650 Li-ion battery and 24 (very bright) 5mm LEDs. They can be switched to use 12 instead, which yields longer runtime. Package states 5 hours with 24 LEDs, and 8 hours with 12. The difference in brightness between the two levels is not nearly as great as I thought it would be. They can also be removed from the outlet and used as a traditional flashlight.
The twin-pack is $19.99 at Costco, and I think is an excellent value. They are perfect in a home-use environment. Perhaps they would work in your application as a supplemental solution.
I'll start with a little background on emergency lighting as practiced in the US at this time, just so we're all starting off on the same page:*
You have two basic types of system, central and distributed. Distributed means that you have boxes scattered around your facility, each box has an AC connection, it trickle charges a battery, if that box loses power it turns on a light and runs it off the battery. Each box is fully independent.
The advantage of distributed is that it's cheap to install. You don't have to hire electricians to spend days crawling around running wires in the walls and ceiling. You can start small and build as fast or slow as you like. If one unit dies a replacement is not that expensive. The disadvantage of distributed is maintenance. You are supposed to test and monitor these things and with a distributed system someone has to walk all over the property with a ladder and test each unit one at a time.
Central means that you have a closet somewhere with a pile of big batteries. When you lose power to that closet the batteries start feeding power to wires that run to lamps scattered all over the building. They all come on. With a central system you test one board, measure one set of batteries, activate it, stroll once around the facility to see that all the bulbs came on, and boom, you're done. It's much faster. The disadvantage is that you have a single point of possible failure for the entire system.
Different facilities make different choices, I believe both are considered code compliant.
90 minutes run time is the current national standard that all these units are designed for. You can make a system run longer, but it will be a custom system, all the commercial stuff is designed around that 90 minute standard. This time is thought to be enough for people to make their way out of the building safely, and hopefully enough time for medical or repair teams to find their way into the property and fix things.
Common Emergency lighting systems are not designed to allow continued operation of the facility. A backup generator would allow this. I have never seen any kind of emergency light that was motion sensing. Such a thing is certainly possible, but it would either be a custom build or a new item not yet widely in use. The system that came with the building was probably designed specifically so as to satisfy code requirements as cheaply as possible. Nothing forbids you to exceed code.
How can you optimize your existing system? Going beyond 90 minutes is easy. Going into multi-day service would be more involved. The first things to do are:
Get rid of the standard incandescent bulbs and replace them with LEDs where possible. I still use a few icans in places where I need a long throw of light. Incan is still good for throw. Everything else has gone LED. They are a good match to the needs of a 12 volt DC system. Look inside every unit. Figure out how big a battery will physically fit inside the housing and upsize all of them. There is normally a lot of unused space in there. Lead/acid is the norm in emergency batteries. You can get into other chemistries if you are comfortable with them.
Come in after dark one night and do a full system inspection. Shut down power to the facility. Don't just turn off the lights, do a full test. Walk through the entire plant using only the emergency lights. Are there places you could get lost? Places where you can't find the exits? Gaps in coverage? Look for flaws. Often incan lights will be aimed squarely in the eyes of people who are using the system. This means you are walking around in the dark with while a light is shining in your eyes. I consider this poor design.
I don't know who uses your buildings. Statistically, mature women are the most likely to have poor night vision. Consider borrowing some ones grannie, have her walk though with you, ask her what she thinks, listen carefully to what she says. Build a system to her needs and you will have a system that works for 99%+ of the population. Maintenance departments often have young guys in them. They normally have good scotopic vision, know the building well, and will honestly not see problems.
(*I am not in fact a lighting engineer, but I'll share with you what I know. I'm on another coast than you and expect regional variations)
If you are comfortable discussing it, what kinds of work go on in your facility? How much light do they need? Can they work at all without reliable mains power? Many places cannot run without it, regardless of lighting.
If this is true for your facility then what you really need is a backup generator sized to meet the minimal needs of your building. You will need something called a "Generator switch" or "Transfer switch" which manages the change between line power and your own power. One of the things it does is make sure that you do not send out power into the dead lines, 'cause repairmen hate it when they shut off all power to a failed circuit, and then find out the hard way that some &^!! customer has energized it from the other side. This whole affair would be the responsibility of an electrician, it is not a DIY kind of project.
If power fails for your area will you still have water? Without water you would probably have to shut down soon anyhow. Do you ever need to heat the building? would you be able to heat it without power? If not, then you'd still have to shut down.
Changes cost money. How important is this project to management? Your budget will affect your options. If they are extremely serious then the ultimate system might be to run a parallel 12 or 24 volt DC lighting circuit, connect it to a set of forklift batteries down in the basement somewhere, and have solar panels up on the roof to top it all up. You could run for years off this. The drawback is the initial cost.
Also some emergency lights pass a small current through the lamp filament at all times, to prove that the lamp is sound and will work when called on. This wont work with an lLED and may cause the "mains healthy" pilot lamp to go out, even when all is well.
I had this problem with one unit. It would fail its self-test when running all LEDs, even though it worked fine. I wound up setting it to run several hundred LEDs and one incandescent automobile marker light. The incan light made it happy, the LEDs make me happy, no fault lights make the inspector happy, so everybody won.
I believe it tested for certain conditions on the lighting circuit, and interpreted 100% resistance (if it tried to pass current the wrong way through the led string) as meaning no electrical connection, or 0% resistance (passing the right way throught the diodes) as meaning a short. I gave it that one bulb, with an intermediate resistance through the filament and all was well
Here we are three years later.
When I bought my first incandescent emergency light, I was disappointed that it only lasted for 90 minutes.
One day while at home depot, I noticed that they had LED lights. To my extreme disappointment they also only lasted 90 minutes!
It seems that they are using nicads with a much smaller capacity than the 6v 4.5ah SLAs of the incans.
Is there a better, longer running option at about the same price point?
I've looked at the Philips/Bodine products (mostly back-up ballasts for fluorescent fixtures) and the usual is also 90 minutes illumination but there were some "Specialty" application extended-run models with up to 4 hours minimum of illumination time. There are also some with run-times as little as 2 minutes but that's just long enough for an emergency generator to fire up and transfer.
As mentioned earlier in this thread, 90 minutes is the "standard" minimum run-time.
Here in the UK, the norm for emergency lighting is 3 hours, rather than the 90 minutes typical in the USA.
Several suppliers sell kits intended to convert a 12 volt, 50 watt or even a 100 watt, halogen downlight into an emergency light, to work a 50 watt lamp or larger for 3 hours needs a relatively large battery.
If similar equipment is available in the USA, it should be possible to utilise it with lower powered lamps.
Use of a 12 volt 5 watt LED should give a run time of a couple of days, depending on how much the internal relay uses.
For still longer run times a central battery system is probably needed. A system designed to supply 3,000 watts for 3 hours, should be able to supply 150 watts for about 60 hours.
150 watts is still a lot of 5 watt LED lamps.
I was an instructor in the USAF and our school had been previously a top secret school and no windows for security reasons. The school had a requirement that all the emergency lights got a press to test once a month, every unit worked perfectly right up to the point we had an actual power outage. Not a single emergency light worked. It seems that the test only tested the light bulb and not the storage battery, apparently the "batteries" had given up the ghost many moons prior. It showed up one glaring (sorry) problem.
Modern systems and codes in the U.S. call for extensive self-test capabilities to ensure the system is fully operational.
Replacing incans with LEDs in your emergency exit fixtures makes them non-compliant. They are designed to provide a given lighting pattern. Violate that and you are open to lawsuits.
As a suggestion do not touch anything related to the code-compliant system. That keeps you out of legal trouble.
If you wish to add supplemental lighting, great. Just remember the emergency lighting is to light a path to exits. Watch you do not confuse people with additional lights to no-where.
If you want hours or days of storage, that is time for a generator, not a battery really. If you don't have enough light to be safe everywhere, then you are open to legal issues if anyone hurts themselves.
What SemiMan said about lawsuits, may not be as true in the UK as in the USA, because in the UK loser pays. In the US, we have warnings on step ladders, that use of a ladder may be dangerous after consuming alcohol.
Personally I modified a couple of 6v units for home use, and gifted a couple. They'll run for ~20 hours, powering a 24 5mm led tent light. For those interested, here is a thread on the plug in the wall outlet flashlight type lights.
Ideally, emergency lighting should have a low voltage cutoff to protect the battery from any outage of sufficient duration to kill the battery. Evacuations kill emergency lighting batteries. Even a weekend outage at a closed business will kill. I have a friend of mine who manages properties for a living and he actually gets quite busy from time to time, running around from building to building, disconnecting emergency lighting batteries...and then hooking them all up again later.
Does anyone know of a simple, cheap, add on solution for emergency lights not equipped with a low voltage cutoff?
Allmost all emergency lights sold in the UK are ready equiped with a low voltage cut off.
On mains failure, the lamps are connected to the battery via a relay. A circuit measures the battery voltage and opens the relay when the battery voltage drops to say 11 volts for a 12 volt nominal unit.
The drawback of this system is that the current used by the relay coil is added to the battery draw.
This limits the run times that can be achieved even with lamps of very low power.
I have here an emergency light that uses a 12 volt 14 AH* battery and a couple of 12 volt 15 watt bulbs for a run time of 3 hours. The relay coil probably uses about 0.1 amp, inconsequential in normal use compared to the lamp current of about 2.5 amps.
If however one tried to greatly extend the run time, then the relay coil consumption becomes significant. With no load whatsover, the relay will run the battery down in about 140 hours, less than a week.
To achieve a moderatly extended run time, I install two of these fittings next to each other, and remove one bulb from each. That gives a run time of about 8 hours, and the use of two fittings each with one bulb only gives the same light as a single fitting with both bulbs lit.
*2 batteries each of 7 AH in fact, in paralell as these are a popular size
Last edited by broadgage; 10-03-2013 at 12:19 AM.
Reason: To add last bit about batteries