Just wondering what's the difference between maintained and non-maintaied emergency lights.
Regards
Steve.
- Steve Lowe
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Non-maintained can only be run from batteries, i.e. when the mains fails or if the supply is disconnected.
Maintained can run from batteries or from the mains, so they can be used for oridinary lighting when the mains is OK too.
On Sat, 20 Jan 2007 12:41:32 +0000 someone who may be Steve Lowe wrote this:-
Maintained lights can be used as ordinary lights. They can be switched on and off like any other light, or left on all the time. If the external supply fails then the light output will either be maintained by the battery, or it will light up by the battery. A typical application would be emergency exit signs in a theatre, which one normally wants to be lit all the time it is occupied.
Non-maintained lights are normally off, but will light if the external supply fails. This is what most people think of as emergency lights.
There are also sustained, also called combined, lights. These have two sets of lamps. One set is fed from the external supply and one set from the battery. Externally and logically this a maintained light, but it is different inside.
There are advantages and disadvantages to the three sorts of light.
For simplicity I have not mentioned lights with an external supply, for example from a central battery system.
Avoid the crappy labels with the now standard stencils. These things are dangerous, as they cut down the amount of light given out by the fitting. I would far rather have more light than a stencil of somebody running.
I find it rather strange that the Exit signs have to have a pictogram of a man running, when we are all told not to run during a fire! Can't even have the word EXIT on the sign as it may confuse people!!!................rant finishes
Yes, but keep in mind that this does have to address people with speech difficultiies suh as residents of Birmingham, Leeds, Manchester and Glasgow....
I've already fitted a maintained one under the stairs, handy when reading the gas meter and to see the RCD when it has tripped.
An expansion of their relative dis/advantages would be welcome though.
They just do different jobs afaics.
NT
On Sat, 20 Jan 2007 12:41:32 +0000, a particular chimpanzee named Steve Lowe randomly hit the keyboard and produced:
Maintained lighting is where the unit is permanently illuminated; non-maintained is normally off until the normal lighting circuit fails, then it comes on after a maximum of five seconds. Both can be powered by fire-resistant ('Pyro') cable, but more usually have a rechargeable battery to give between 1hour and 3hours illumination.
Maintained lighting is required in premises where the lights can be dimmed below the minimum level of illumination (theatres, nightclubs, etc), or where alcohol is served. IIRC, they may also be required in places where any delay between the normal lights going out and the e/lighting kicking in may cause panic, but don't hold me to that. Everywhere else can use non-maintained.
Maintained lighting has the advantage that one can see instantly when a bulb has gone. OTOH, a bulb will probably go a lot quicker if it's on all the time.
Is he running or just walking? Like the green man in pelican crossings? Are there speed lines?
Not every one can read english. How many languages do you want on your light? Anyone with half a brain cell should soon pick up what the local language word is for "exit" by observation but that assumes the lanuage uses the roman alaphabet, not some other script or characters. Pictograms are pretty much independant of language apart from I and O for on or off or is it off and on?
On Sat, 20 Jan 2007 21:40:43 +0000 (GMT) someone who may be "Dave Liquorice" wrote this:-
Everyone I have asked (not that many people) thinks he is running.
On Sat, 20 Jan 2007 19:19:03 +0000 someone who may be Andy Burns wrote this:-
A non-maintained fitting may not light when necessary, so it is necessary to regularly check that the tube lights up. However, the tube may fail between the last time it was checked and when it is needed. Those of a sensitive disposition may also complain about the unlit fittings "spoiling" the look of a room.
With a maintained fitting tube failures can be spotted more quickly, but it is also more likely that the tube will fail in use when it is in emergency mode.
Sustained fittings can be harder to check that the emergency tube is working and thus checks may fail to reveal failures.
Note that checking the battery involves making sure the fitting runs for the appropriate time, which is different from checking the tube which just involves checking that it lights up.
Exactly what I have on the list to do next weekend, once the replacement batteries arrive this week to repair the 2 lights I discovered buried in the garage the other day! Both are unused but 13ish years old and I don't expect NiCads that old to hold much charge!
Alan.
I bought 4 from a wholesaler a few years ago for £1 each, because although brand new and unused, they were past their battery change dates. I connected them up, and they're still giving over 3 hours light. I wouldn't assume an unused NiCad to be dead (and the replacement high temp NiCads these use often cost more than a whole new unit).
Ditto. Thought I was everso clever - until the first powercut when I couldn't see the all the normal household obstacle course between me and the light inside the cupboard under the stairs (behind a nice light proof door!)
;-)
Any emergency lighting system should be tested for real regularly.
The only time I've personally been in a situation where one was actually needed was many many years ago on the opening night of BBC2 when there was a drastic power failure at TV Centre. We were rehearsing Dr Finlay's Casebook, and of course studios have no natural light - and what's more change their layout regularly although there is a fire lane round the outside. The emergency lighting system which would have been a central lead acid battery type did come on but only lasted a few minutes instead of the spec of one hour. Luckily one of the crew was close to the big scene dock doors and opened those which allowed in some light from the nearby street lighting. I shudder to think what the outcome might have been if if fast evacuation was essential.
Easy answer to that.
Put under-stairs cupboard door on an opening spring and have it held closed by an electromagnetic latch.
Power fails, light lights, door swings open and hits someone in the face.
Owain
Thanks - much clearer now - especially with the light on !!!
- Steve Lowe
- E-Mail : snipped-for-privacy@usa.net
- Before Replying Remove .NO.SPAM
- UK Resident although my e-mail address is usa.net
I certainly wouldnt assume that, NiCds dont work or behave like lead acids.
NT
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