The role of emergency lighting is a key factor during building evacuations (power cuts, evacuation alarms, serious incidents, etc.). Moreover, it is indispensable that the time intervals be triggered in accordance with regulations for safety installations, which vary from country to country. In general, this trigger period does not exceed 0.5 seconds for exit and anti-panic lights and 0.2 seconds for high risk areas. Moreover, emergency lights must ensure duration of three hours functioning depending on the environment.
These environments are classified and have a relevance code, which establishes, on the basis of the risk level, if the duration required must be one, two or three hours, depending on whether the place in question is public and carries a high evacuation risk (such as hospitals and medical environments, lifts, car parks or schools), or private, such as homes or places where evacuation can be accomplished under safe conditions in an hour. Another important aspect required by the standards is the charging time i.e. the time it takes the emergency kit to function. In general, an emergency device must guarantee independent operation for at least one hour after having been charged for 12 hours.
Over the last 20 years, a series of standards have been implemented and applied aimed at the way installations should be built, affording importance to those aspects related to safety lighting. This has come about owing to the fact that increasingly more users and customers understand the importance of ensuring lighting in risk situations where, in the event of a power cut, the lights will operate under what have been defined as “emergency mode” conditions.
Safety lighting devices (self-contained and central) must ensure two basic functions:
Anti-panic lighting by means of an emergency light:
Example of emergency light
Capable of avoiding situations of danger generated by panic during evacuation, ensuring minimum lighting to facilitate the identification of an escape route and help intervention.
Pre-evacuation lighting by means of a sign light:
Example of sign light
Capable of ensuring the safe evacuation of occupants by means of the exit routes, signalling the way and the obstacles.
Signal visibility depends on the ratio between the distance from which the signal is observed (d) and the height of the light (p). It is regulated by a standard. For Spain, this is the UNE-EN 1838:2000 Standard.
Graphic of signal visibility
d = Viewing distance
p = Signal height
s = Constant “100″ for signs illuminated externally
Constant “200″ for signs illuminated internally
Moreover, the amount of lux at floor level, or one meter above this, is specified in the same standard.
Amount of lux at floor level graphic
In general, except for some particular local rules, the reference international standard indicates that the following lux values are required:
• 1 lux for exit route lighting
• 0.5 lux for anti-panic signs
• 15 lux for high risk areas
Graphic of lux values international standard
Each emergency “kit” consists of an inverter/converter connected to a driver or electronic ballast that kicks in should the power supply fail to the latter, a central or self-contained battery and LED signals. The LED signals have basically two functions: signalling the presence of voltage on the grid and indicating the charge status of the battery.
• Proper operation (generally a green light comes on)
• Faulty operation (generally a red light comes on)
Obviously, emergency lighting devices are subject to inevitable ageing. Ensuring the proper operation of these involves regular checks and maintenance. For Spain, this aspects are defined in the Spanish Quality Assurance Agency (AENOR) standard UNE-EN 50172:2015.
These regular checks consist of operations capable of verifying the operating condition of the safety lighting and signalling devices, where they have been installed, and identifying any problems or faults.
These operations can be conducted by qualified personnel, or by end users with no experience, given that, visual inspection suffices as a first step.
It is necessary to ensure that the device is live, by checking that the charge LED is ‘on’ and electrically checking that each device stays ‘on’ over the entire duration required by the standard by cutting off the power supply to it.
Example of emergency Kits
Emergency devices with a built-in self-diagnosis or adjustable system:
Emergency devices with a built-in self-diagnosis or adjustable system
Obligatory checks are done on these types of devices automatically, without any need to cut off the power supply in the premises. This is possible owing to a smart integrated electronic circuit that is capable of simulating a periodical power cut to verify that the inverter responds and that this response is practically immediate.
In general, these checks are conducted randomly on all the kits involved. They are conducted every week to verify proper operation and once a year to check duration. Operation and duration tests are defined accordingly.
It is necessary to verify that the device is fit to ensure its functions, checking the light indicator included or consulting the report record at the control centre. In general, these installations can be smart programmed, generate a feedback report and are managed by devices that operate in accordance with the Digital Lighting Addressable Interface (DALI) protocol.
Regular maintenance of the lighting installation and of each emergency device is essential to ensuring that these are in proper working condition.
Rules for proper maintenance are also valid for lighting devices with an emergency kit. Corrective actions and regular maintenance interventions are indispensable to eliminate damages and operational faults detected during checks, or simply to maintain the entire assembly in efficient operating conditions and, therefore, to ensure safety in time. Any problems detected must be correctively remedied by a qualified operator:
Corrective interventions, regular maintenance operations and technical fitness certificates are specified in detail in the aforementioned current regulations.
It is important to know that whoever manages public buildings, as well as work environments and collective structures (schools, hospitals, etc.), is the person responsible for the safety of their occupants and thus is subject to legal liability with respect to emergency installations as such.
Actions that can be taken on apparatus with internal batteries or central power input with respect to checks on the condition of all the components:
• cleaning the signals that indicate escape routes
• cleaning of the transparent cover and of the devices’ reflectant screens
• adjusting terminals and connection systems
• replacing bulbs or fluorescent tubes when faulty
• replacing batteries when faulty
On the other hand, for the central emergency group:
• adjusting terminals and connections
• cleaning batteries and lubricating clips
• cleaning cooling grilles and fans
It would also be a good idea to conduct a daily check that the power supply indicators to the devices are in order (this is just a simply visual check and requires no operating tests), a monthly check conducting an operating test (simulating a power cut) and a yearly check on the functioning and the duration of each lighting device.
Proper maintenance and safety devices, when planned for in the design stage, can save lives in situations of danger.
Donatello Schiavon, Area Sales Manager at ELT ITALIA
