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 versions 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.
Warning. Using new generation T5 lamps (14W- 80W) in a non-maintained installation is not recommended because of the following: T5 Lamps need a minimum run in time of 100 hours before the lamp can be run at a dimmed level. Most emergency invertors run lamps at a dimmed level under 50% of the lamps rated wattage. Running the lamp at a dimmed level during the initial 100 hours can have the following effects:
- Lower lumen output than normal
- Decreased lamp life
- Unstable lamp colour
- Swirling of lamp gases largely reducing lumen output due to impurities in the lamp manufacture process. These impurities are normally burnt from the lamp during the first 100 hours of its life.
If the lamps can be run successfully for a minimum of 100 hours before being dimmed, then dimmed operating conditions can be achieved. Because this is a costly exercise, and a normal inverter does not have the ability to achieve this recommended burn in period, lamps such as the new generation T5 lamp should be avoided in maintained or sustained installations otherwise the C0 and C90 calculations may not be correct. Another concern with T5 lamps is being able to run them at the optimal temperature to get the maximum lumen output. A boast charge should be used to ensure that the lamp is at the correct operational temperature before dropping the current to the lamps. Br>Sustained versions 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 versions Maintained emergency lighting refers to the use of one lamp which is powered via a ballast in a normal situation and via a 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.
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