Central bat v distributed bat emergency lighting opinions

[MattChan]

Not sure if any of you chaps could help me out.

I need to gather some real world info on the view of installers and system designers on central battery v distributed battery emergency lighting systems for stairwells and corridors in flats and care homes etc.

I have heard that some local authorities will not have central battery systems installed in their properties, anyone got any experience of that?

Central battery advantages:
Batteries tend to not need replacing so often.

Central battery disadvantages:
Install cost
Cabling needs to be FP200 to keep lights on in a fire.
Damage to a cable can take out other lights
Volt drop at end of run if 24V is piped about

Distributed battery advantages:
Cheap to install

Distributed battery disadvantages:
Expensive to maintain due to many batteries that don't last that long.

Anyone got anything else to add to those lists? Any system designers out there care to say which they would choose?

Any info greatfully appreciated!

 

[JohnD]

I have a central emergency power lighting in my commercial premises, it is rather a nuisance. The power box is bigger than a filing cabinet. It has a number of lead-acid batteries similar to (not the same as) car batteries inside which need to be replaced at intervals at great cost. The whole thing has to be regularly tested and logged; we do it each calendar month so it doesn't get forgotten, and it has an annual inspection. If there is ever a fault it needs the lighting co to find and fix. It has a bank of internal fuses as there are a number of lighting circuits.

IMO self-contained ones would be much less trouble to install and maintain. They have LEDs now which can give good light for a long period. I had self-contained ones in my previous premises, which were much easier to look after.

 

[MattChan]

Thanks John

I have been asked to design LED luminaires and an emergency backup system for them so I am just grabbing the background info.

I don't like the central battery idea but I fear I may be steered down that route by my customer!

 

[ban-all-sheds]

Ask him why he thinks that a central system would be preferable?

 

[RF Lighting]

Self contained units are by far the best option.

You want the emergency lights to come on if the local circuit fails for what ever reason. This does not happen with central battery systems. They will only light in a network failure.

The cost and labour required to initially install, and then keep a central system running is prohibitive compared to swapping small batteries in self contained units every five years.

I can see no advantage to central battery units these days.

We fitted a central battery system in a full refurbishment theatre project two years ago. This fed into an invertor to keep the normal lights running in a network failure, with self contained units on the exit routes should the local circuit or central battery fail. Completely overkill in my opinion, but it's what the clients architect specified.

There's a local council run community hall near me with central battery emergency lighting. The council stopped maintaining it about 5 years ago, and as a result it no longer actually works. They are now installing a full new system of self contained units at a huge cost.

At Leeds grand theatre they have a central battery system dating back years and years which switches the auditorium lighting on to 240V DC in a mains failure. We did some maintenance on it a couple of years ago and it's still working really well, although finding a DC rated changeover contactor for that sort of current would be interesting these days!

 

[MattChan]

Thanks chaps, thd luminaires would be both emergency and normal lighting in the same unit, we would just knock back the number of LEDs on in emergency conditions.

Albrights seem to be the only people I could find that did the high current DC contactors i used on another project. I think the one i had was a continually rated 100A 24VDC job, there was some fun PCB design with those currents being carried!

 

[bernardgreen]

Local batteries and lamps that come on when mains fails.

Central battery systems were "sensible" before the invention of compact rechargeable batteries but are now not "sensible" as one failure can extinguish all emergency lighting.