Photoluminescent Exit Signs

[Senselessticker]

I've been instructed to specify a photoluminescent exit sign to be compliant with NFPA 101. Photoluminescent signs seem to becoming very popular. I have in my possesion, a sample sign from Jessup Manufacturing Company. There is a warning on the front of the sign that 5 foot-candles are required on the face of the sign for the sign to remained charged.

When doing lighting calculations, there is a great difference in horizontal and vertical illumination. My calcs are showing that 5 foot-candles of vertical illumination are often not attained at the mounting height for the sign when considering the existing fluorescent lighing. However, when calculating horizontal illumination, there are much more than 5 footcandles at the horizontal plane of the mounting height of the sign. I've tried to contact the manufacturer concerning this matter, but have yet to get a response from someone knowledgable with this warning. The sign is UL 924 listed, and NFPA 101 approved.

I'm curious if anyone out there has experience with photoluminscent exit signs, or if anyone else has realized a problem of providing sufficient face illumination for these signs. Any help is greatly appreciated.

 

[advidana]

The warning is correct if you don't have 5 footcandles they will not charge up properly. I would recomment that you place a light fixture with some uplight near the exit sign or lower the exist sign or just use a different type of exit sign fixture one that is powered. I use the self power type all the time but I make sure that the 5 footcandles are provided. I also prefer the 20 year life over the 10 year life. I like these type of exit signs because the battery types fail a lot due to lack of maintenace. I usually mix them up in the installation. remember that the seft power of exit signs are expensive.

 

[Senselessticker]

Thanks for your input advidana. I've been researching photoluminescent exit signs, and have run into a big mess concerning who approves / disapproves of these signs. NEMA does not approve, EPA does not approve, and there are some others that can't remember. So here's what I gather from all of this:

The warning label (that I suppose is mandatory on all PL signs) states:

"Caution: Minimum of 5 foot candle external unfiltered flourescent, mercury vapor or metal halide illumination must be present on the sign face at all times of building occupancy".

Yes, the sample sign I have in my possession actually has fluorescent mispelled on the sign. According to the NFPA the term "occupancy" is defined in NFPA 101, 2002 as:

"the purpose for which a building or portion thereof is used or intended to be used".

Hence, those 5 foot candles are required 24/7 unless the building as been abandoned...right??? These signs are designed to charge from ambient light, which, under normal lighting conditions.....they do. However, if a facility wants to save some energy during off shifts (turn off some lights), it must provide a designated fluorescent fixture (defined by the NFPA as a "reliable source" as determined by the AHJ, capable of producing the 5 foot candles on the face of the sign during this time. The photometrics of most fluorescent lighting does not direct light at, say, the top of a door (where an exit sign most likely will go). So really nothing is gained when is comes to saving energy....right???? I've ran numerous lighting calculations on this and from "normal" 2x4 fluorescent fixtures that run on 32 Watt T8 lamps. It takes the room and/or corridor being almost fully lit to achieve 5 foot candles for a normal ceiling height (8-12 feet). What I'm trying to say is that the sign will not charge properly simply placing it near a fixture, unless there are about 20-30 foot candles on the floor (i.e. all the lights are on the room or corridor)

If I sound uneducated concerning emergency lighting and/or PL technology, please forgive me. It just seems to me that PL exit signs seem to be a waste of money and dangerous, unless of course there's about 20 Watts worth of light aimed directly at the sign...all the time.

I'd really like to hear some other opinions on this matter. There seems to be quite a bit of disagreement between NEMA and the UL/NFPA concerning this.

 

[advidana]

The labor cost of installing the fixture is less. You don't need a electrician to install it. Conduit and wire are not necessary. The draw backs are that the cost of the fixture is high and you must meet the room lighting levels to charge the exit sign light fixture.

It is a pain- but All light fixtures have different uses and requirements, so a do-all light will not alway work. You did right by checking the requirements. Tell your client or boss to think again before giving you instructions.

 

[robertb]

Do not forget to specify the requirement of legal disposal of signs at the end of life.

 

[Senselessticker]

I've found nothing in the product information about photoluminescent signs having specific disposal requirements. Also, there is a VERY big difference in self-luminous and photoluminescent signs. Self-luminous are usually fueled by tritium. Photoluminescent signs are powered by fluorescent light.

If anyone is interested, do a google search for NEMA Exit Sign Safety to find a very interesting report on this sign matter.