NEMAVue Video's on YouTube

Storm Reconstruction: Rebuild Smart - Reduce Outages, Save Lives, Protect Property

Subscribe to NEMAcast

ANSI Z535 Standards

eicareers Career Center

NEMA Currents

Green in color only, sometimes. Concerns over advertising claims for Photoluminescent exit signage

Caveat Emptor, and Carry a Flashlight?

Photoluminescent (PL) exit signs can be an excellent addition to the life safety outfitting of many facilities.  Their ease of application and use lend them to be favored by many building operators and sometimes even required by life safety codes.  However, PL signage must be applied and maintained properly and has its limitations.  Too often advertising claims gloss over or ignore some very critical points that anyone considering PL signage should take into account as they consider implementing it.

Photoluminescent exit signage marketers often claim the signage requires no electricity to operate because it can charge off ambient light in the space.  It is often claimed that this feature further makes PL exit Signage "Green" and a great solution for anyone trying to save energy.  This claim is in itself contradictory, as it establishes a need for light in a space to charge the signs and thus some electricity usage.  Whether or not something is "Green" is subjective, but claims of zero electricity usage appear rooted in the logic that the lights in the building will be turned on for the occupants, and thus light provided for the PL signage.  This claim also ignores the fact that a PL exit sign needs a specific minimum amount of light (lux) hitting it to sufficiently charge the photoluminescent material.  If one accepts that many facilities turn out most or all of the lighting at certain times when the building is dormant, the PL signage would be discharging some of the time and not fully charged during and just following this period.

The accepted charge time to reach full performance for most PL signage is one hour.  This complicates the safety of having PL signage as the primary exit marking if someone enters the building during normal off time when lights are routinely dimmed or turned off.  If an emergency occurred before the PL signage was charged, the safety of those inside would be lessened by some factor.  This of course does not take into account that there may not have been sufficient ambient light in the space around the PL exit sign to begin with.  If the lights are always on, because of the needs of the PL exit signage, the claims of energy savings may not be realized.

Having established that PL signage needs light (electricity and dollars spent) to charge, the next issue becomes how much.  All the various life safety codes require a certain amount of light (lux) hit the PL exit sign to fully charge it, and in some cases require dedicated emergency circuit lighting, thus negating all ambient light only, zero electricity claims.  An uneducated purchaser/installer also may not be well versed in determining light levels nor capable of evaluating proper code compliance.  PL exit signage installed in a normally lit passageway may not be receiving sufficient light to fully charge and thus not meet code.

Additionally, some life safety codes allow for lower illuminance for PL signs as compared to internally lit signs.  For instance, UL 924 requires less luminance by a factor of ten for PL exit signage as compared to internally (battery/electric) lit exit signage.  The performance characteristics of the photoluminescent material also contribute to a steep decay in luminance over time.  A properly functioning battery operated LED exit sign has little if any charge over the first critical hour of discharge time following a power loss.  While properly installed and properly functioning PL exit signage may meet its pertinent safety code standards, it will often be dimmer than a comparable electric (battery) sign.  At this time there is a dual standard for exit signage, divided between PL and electric.

These are just some of the concerns regarding photoluminescent signage.  As with any matter dealing with life safety, anyone considering using PL exit signage to replace existing internally lit signage would do well to research the practicality and feasibility themselves, and not rely too heavily on manufacturers claims.  Further discussion of this subject may be found in the soon to be released NEMA Lighting Systems Division white paper LSD-46.

Posted 11-12-2009 12:11 PM by Boesenberg, Alex


Charles V. Barlow wrote re: Green in color only, sometimes. Concerns over advertising claims for Photoluminescent exit signage
on 11-17-2009 3:10 PM

Mr. Bosenberg raises several concerns about (non-electrical) photoluminescent emergency lighting - specifically code compliant photoluminescent exit signs.

I am the operations manager for EverGlow, a manufacturer of code compliant photoluminescent exit signs and exit path markings.

I believe it is naive for Mr. Bosenberg to assign questionable advertising claims for exit signs to manufacturers & suppliers of photoluminescent signs & markings without also considering questionable claims made by manufacturers and suppliers of LED exit signs.

Suppliers of both products have been guilty of exaggerating the advantages and benefits of their exit signs.  There is room for both lighting technologies in the emergency lighting market.  Life safety can be improved when both electrical and non-electrical lighting are used appropriately.

There have been problems at installation and with maintenance after installation.  Photoluminescent exit signs have been installed in locations where there was insufficient ambient lighting.  LED exit signs have been installed without connection to an electrical circuit.  Electrical exit signs of all types- LED, Fluorescent & Incandescent- have often been poorly maintained so they could not operate properly during emergency conditions.

There have been misleading claims of longevity for electrical exit signs.  Even the best LED exit signs with battery or generator backup power supplies do not last the 20,000 - 50,000 hrs that some suppliers claim.

For all the energy efficiency advantages that LEDs offer, for the lower maintenance requirements of LED exit signs, there is no practical way to determine if an LED has dimmed to the point of being unsafe.  Incandescent and fluorescent lamps failed in noticeable and predictable ways; LEDs dim as they fail.  Is this a safe failure mode for emergency lighting?

To assume that a code compliant photoluminescent exit sign only provides the necessary luminance 60 minutes after the interior lights are turned on is as silly as saying that electrical signs with battery backup power are only safe after 7 days of charging.  Both phrases are taken from the performance standard UL924 and assume that, once installed, the signs have somehow reached a state of complete discharge.  It is rare that a building is ever so dark for several days- the time it takes for a photoluminescent sign to completely discharge and the time it takes for an electrical sign battery to lose any charge it was storing.

There is only one performance standard in the US for exit signs- Underwriter Laboratories 924.  UL924 governs both electrical and non-electrical exit signs.  Canada is moving toward a similar standard.  Testing of both sign technologies requires submission of samples with completely discharged batteries (for electrical signs) and photoluminescent signs that have been stored in the dark for at least 72 hours.

If the ambient lighting where a photoluminescent exit sign is installed is only 5 ft-candles on the sign face (very dim), then the completely discharged sign will perform properly after 60 minutes.  Once installed, the sign is unlikely to ever be completely discharged again because buildings are rarely ever fully dark for long periods of time.  For new installations of electrical exit signs, or replacement batteries, the initial charging time of 2-168 hrs is not likely to be repeated during the life of the sign or the battery.

Actual lighting in corridors where exit signs are typically installed usually exceeds 5 ft-candles (above the door).  This dim lighting would result in only the code required minimum of 1-2 ft-candles of illumination at floor level.  Many building occupants would consider this an unacceptably low lighting level; some might consider it unsafe.  EverGlow always asks any potential customer of photoluminescent exit signs about ambient lighting and approval by their code inspector.

There is no question that photoluminescent exit signs are green.  EverGlow aluminum signs & markings consume ZERO energy (yes, they do require minimum ambient lighting), and contain ZERO radioactive, toxic or vinyl components.  We think that less lighting in the corridors is a good energy saving move; that photoluminescent exit signs should not be installed where there is not sufficient normal lighting to properly charge our signs.  From a practical standpoint, most building occupants demand 20-40 ft-candles of illumination on the desk tops and work areas; they feel most comfortable, safe and secure with a minimum 10-20 ft-candles of illumination in the corridors.  We think it is necessary to illuminate the corridors in the built environment and wise to use that same lighting to charge reliable and effective photoluminescent exit signs.

Finally, sales of photoluminescent exit signs and exit path markings are increasing as life safety, fire safety and code officials recognize that these passive lighting systems can replace or supplement electrical emergency lighting systems.  We can all do a better job increasing life safety and reducing maintenance costs in the built environment.

Markus Thrun wrote re: Green in color only, sometimes. Concerns over advertising claims for Photoluminescent exit signage
on 11-19-2009 9:31 AM

As the chairman PSPA. a non-profit association, founded in 1991, I would like to voice my concern about the ongoing comparison of electric and non-electric (phosphorescent) signage or markers. This discussion is a s old as both technologies and never comes to a serious conclusion. However, it has been proven by several studies that PL installations provide best performance in egress markings. The purpose of photoluminescent directional safety way guidance sign markings is two-fold: First, during times of evacuation under full or emergency lighting, the directional safety way guidance sign information communicated by the markings will identify the egress path. The goal is to have uniform, consistent markings in buildings to give occupants a greater level of confidence concerning the direction of movement, which, in turn, can result in achieving faster egress speed to the final exit with less risk of injury. The second purpose is to be a supplement to the normal and/or emergency lighting systems should they fail; especially under the influence of smoke. In this situations the photoluminescent markings will communicate the visual information necessary for egress during a crisis. It is wrong that it is some kind of agreed charging time of 1 hour for PL products. The charging time is always a result of light source, illumination, temperature, duration and last but not least the product. I may take only a few seconds to charge a PL sign sufficiently, or even hours, depending on the in situ lighting fixtures. This is part of the installition plan and has to be considered prior installations. Nobody would take an electric sign to a place with unsufficient voltage. Nevertheless there is no need to fully charge a high class PL product, because it will provide its visibility long before the full charge. It is agreed in many codes and standards that 0,3 mcd/sqm is the minimum luminance to realize a marking. And I totally agree with Mr Charles Barlow that in a building under normal conditions a sign will never totally discharge.

Again, both systems have advantages and disadvantages and result into an omproved safety level if provided properly.  

John Creak wrote re: Green in color only, sometimes. Concerns over advertising claims for Photoluminescent exit signage
on 11-19-2009 3:54 PM

I think the tone of the replies already received to this blog are exactly right. It is really time that the dinosours of the electrical industry start to look inwards rather than outwards for the source of their difficulties and obvious consumer concerns. Most people do not know that Photoluminescent signs and markings have taken over 50 years of research and evaluation to develop into a serious alternative provision to electrical systems for escape route lighting and signage. The prime driving force for their use has always been the notorious unreliability of electrical systems and limited options for placement to be useful at the time and position that people needed them most. The incidence of power outages without particular hazard to evacuees has comparatively safely demontrated the perecentage of failures of poorly maintained systems. The first terrorist act in the World Trade Centre highlighted the vulnerability of electrical systems to explosion or fire. Many people are still ignorant of the fact that most electrical emergency lighting systems are only activated on loss of the mains power supply leaving electrical exit signs dark and non illuminated in an emergency without mains power loss.

The time has come to recognize the complementarity of the two systems and to use them BOTH intelligently with sufficient risk analysis and objectivity.

It is true that the photoluminescent industry has attracted a number of slogan and marketing hype new comers with little knowledge and experience. It is equally true that the electrical emergency lighting industry is full of manufactures of units that are so cheaply produced that they are never reaching the reliability levels that clients are reasonably expecting. All manufacturers and installers of safety products need to both be careful of their claims and to deliver relaible and consistent products and services. JALITE as a company has now over 30 years of knowledge and experience of photoluminescent products and would like to record that it has a clear policy that it will not make claims it can not substantiate through real experience. Long term full strength and reliable companies in the photoluminescent industry are few and far between as we suspect is the same in the electrical emergency lighting industry. Ultimately the market place will decide what is really valued. wrote re: Green in color only, sometimes. Concerns over advertising claims for Photoluminescent exit signage
on 03-28-2011 2:32 PM

Green in color only sometimes concerns over advertising claims for photoluminescent exit signage.. Smashing :)

Emergency Lighting wrote re: Green in color only, sometimes. Concerns over advertising claims for Photoluminescent exit signage
on 04-14-2011 11:20 PM

In my experience, if you are going to install emergency lights and exit signs, it makes sense to purchase emergency exit combo fixtures instead of separate signs and lights. As long as the fixtures are close to each other this will work. If the fixtures are far away from each other you will need to buy an exit sign and an emergency light.



That place has a wide selection of fixtures. Their combo models are really easy to install. Friendly service to. And to all of you who like photoluminescent, they have those exit signs as well. wrote re: Green in color only, sometimes. Concerns over advertising claims for Photoluminescent exit signage
on 06-02-2011 5:56 PM

Green in color only sometimes concerns over advertising claims for photoluminescent exit signage.. Outstanding :) wrote re: Green in color only, sometimes. Concerns over advertising claims for Photoluminescent exit signage
on 06-04-2011 6:18 PM

Green in color only sometimes concerns over advertising claims for photoluminescent exit signage.. I like it :)

Add a Comment

Remember Me?
Copyright © 2014 NEMA. All rights reserved.