Making Sense of Maintained / Sustained or Non-Maintained Technology
Emergency luminaries and exit signs are available in many different formats. Each format has its own benefits, but which format best suits your application?
Non-maintained emergency lighting refers to the use of a single lamp, which only becomes lit in emergency situations. Typically non-maintained emergency lighting is used in emergency luminaries and not with exit signs (in New Zealand non-maintained exit signs are allowed).
Non-maintained luminaries should be used in areas where the building is normally lit via another lighting source but relies on a non-maintained emergency light in an emergency situation. Non-maintained lighting is preferred in these instances because it is not wasting power in normal situations.
Sustained emergency lighting refers to the use of two lamps; one lamp is powered via a ballast / choke or transformer, while the other lamp is powered through the use of the inverter. The emergency lamp is only lit when an emergency situation occurs, and the standard lamp is only lit when the normal supply power is available.
The standard reason for using sustained lamps is to ensure that the emergency lamp is in a working state when an emergency situation occurs. In cases where a lamp with a short lamp life is used, sustained lamps are a safe option. (For example mini T5 lamps 4W-13W which have an average life between 1000-8000 hours).
There is very little reason why lamps with long lifetimes, such as new generation T5 lamps should be used in a sustained emergency device as they have economical lifetimes of over 18000 hours or even LED or CCFL which have lifetimes over 50000 hours. (See problems associated with T5 lamps in Non-maintained applications as these problems also affect the sustained lamp)
Maintained emergency lighting refers to the use of one lamp which is powered via ballast in a normal situation and via an inverter in an emergency situation.
Maintained emergency lighting is the most commonly used configuration for emergency lighting. It circumvents all the problems associated with burn in periods for lamps (such as T8 and T5 technologies), while providing a cost effective solution for both emergency lighting and exit signs. Commonly used units that employ cutting edge technologies such as LED, CCFL or T5 should use a maintained configuration.
EXAMPLES OF EMERGENCY LUMINAIRE CONNECTION TYPES