Sustained Emergency Lighting

by Steve on September 10, 2010

Sustained Emergency Lighting

An ElectriciansBlog reader asks the following question;  I don’t understand that when I go into communal lounges with escape routes that some of the dwellings have sustained emergency lighting and some have not.  It makes no sense to me and there is no consistency because some of the communal lounges are larger than the ones which have emergency lighting. Could you explain this please. Thank you.

I agree that there is often no consistency when it comes emergency lighting systems.  ‘Sustained’ emergency lighting is usually used as the next best option to ‘Maintained’.  The only difference being that Sustained has separate lamps for emergency and normal use and Maintained uses the same lamp for both operations.

Installations in some premises have permanently illuminated emergency lighting luminaires.  This always seems to be rather wasteful especially when a building is not in constant use. I have listed the options below and would be interested to receive further comments and views.

Maintained emergency lighting – usually has one lamp which is switched on the normal lighting supply  (with other lights in the same area) or is permanently illuminated.  That same lamp also illuminates power failure via the battery.

Sustained emergency lighting luminaires usually have two lamps.  One is used for normal lighting and the other is for emergency use.
This type of fitting is a requirement in buildings such as theatres or cinemas where fire exits and escape routes are required to be illuminated only when the lights are dimmed for a performance.  Because the emergency lamp is not regularly used it is obviously less likely to fail. 

As far as I know there is no other requirement for the lamps to be permanently illuminated.

Non Maintained emergency lighting – illuminates only on power failure.

T5 Lamps
The use of 14-80watt ‘new generation’ T5 lamps is NOT recommended for use in non-maintained emergency installations because running the lamp at a reduced level during its first 100 hours of use (ie. fed from a battery) can:

•Lower lumen output than normal
•Decreased lamp life
•Create unstable lamp colour
•Cause swirling of lamp gases which largely reduces 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.

Read more about T5 lamps and the use of T5 lamps in emergency lighting installations.

Read more about Emergency Lighting.

{ 3 comments… read them below or add one }

Abdelaziz ghieth June 1, 2018 at 16:22

I am happy for your information

Steve Barwick August 27, 2015 at 14:51

Thanks for the reminder about EL, six years ago I was able to explain to the others of a team of six maintenance electricians, all of which had forty years + experience, The difference between the types of EL.
But having just applied for a position which involves maintenance, and possibly design of new circuits involving emergency lighting, I had to remind myself what ‘sustained’ meant.
The only shame is that I am unable to print this valuable information for my own personal use.

Emergency Lighting September 23, 2010 at 19:29

Nice article and good piece of information Im going to add this to our twitter page and reference in our blog.

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