Battery banks for em lights

[wattsup]

I haven't seen such a system for many years not sure how they operate.
Anyhow got a call to find a fault on such a sytem, going tomorrow...
They say they have a bank of several batteries, when the building is empty they switch off, via a 20amp switch fed from local db. When the building is in use they switch on and all emergency lights are lit maintained (about 30).
Now when they switch on, none are working....
Seems a crazy system...all wired in micc.
Would the 230v supply, feed a contactor/relay or a trickle charger for the batteries, or both?

Anyone know anything about this sort of set up?

I will advise to update to latest methods but I'm sure the costs would be a factor.

The building does have a current fire regs cert, inspected yearly including em lights and fire alarm

 

[boatnik1]

Sounds a bit strange. Presumably just emergency exit lights. I would have thought the lights would stay lit when the mains were killed, or maybe there's a switch on the battery bank instead of the mains.

Alternative 1/ The lights could be standard fittings with internal batteries being supplied from 230v mains and the MICC is just the supply from the mains through the 20a switch. Are the lights just daisy chained or are there separate going to each light from a JB or Board. In this case just a normal power check.

Alternative 2/ would be MICC feeding low voltage lights from a central battery bank which would have the 20a switch supplying a charger to keep the batteries charged. In this case check that the batteries are fully charged (each 12v battery should read about 13.8v) if batteries are flat then check supply to charger and if OK then suspect bust charger.

Alternative 3/ and least likely is That somebody has used an old computer UPS which houses a battery bank and an inverter which runs from the mains while available and battery backup when power fails. The lights in this case would be standard 230v types
If this system is in place then dump it and replace with Alt 1 if the lamps are mains powered or replace with Alt 2 if the lamps are just LV types (e.g. 12v)

 

[wattsup]

Thanks boatnik
No not just exit lights, all lights. I know, strange...don't know how the system passed, and has done for many years (so i'm told), kill the supply lose the lights?
I'm going to take a look this morning.
The 'feed' is on a 12-way grid along with other normal lighting, so i presume a feed to a relay or something.

When open for business all switches turned on, one of which operates em lights. When closed all switches turned off then the em lights go off..

 

[oldtimer]

M&S had a system like this fitted to their stores if I remember correctly ther was a hold off contactor fitted at the charger/battery unit that had individual circuit fuses fitted so when the mains dropped out the lights came on sounds a bit dodgy but when it came to maintenance all you had to do was make sure the batteries were topped up (i would check that if I were you) unless they are sealed units and if they are then check them out with a ACT battery tester. You may think tha the modern em light fittings are this Biz but as I have explained previously sealed batteries only have a 5 year lifespan and the building I work in is 5-6 years old and yep were are finding that the battery packs are starting to go

Also look at the panel door I could be wrong but there I am sure there is test button/switch that allows you to test the lights without dropping off the mains

 

[boatnik1]

I'm definately curious to hear the outcome of this one. I just don't understand why the lights would be on a battery bank if they don't come on when the mains are switched off.
They might just as well be mains lights unless there is some sort of relay to switch them on to the battery during a normal failure.
The fact that they go off with the mains would seem to imply that there is also a mains operated relay or the 20a switch is in the battery circuit.

 

[oldtimer]

Depends how they are set up ie lights come on when power goes off or lights stayon 24 hours a day ie non-maintained or maintained.

I have also seen i strip light in each rooom fed off a UPS system

 

[boatnik1]

Depends how they are set up ie lights come on when power goes off or lights stayon 24 hours a day ie non-maintained or maintained.

I have also seen i strip light in each rooom fed off a UPS system

I know that oldtimer, but the weird thing with this system is that it seems intended to work so that the emergency lights are only on when the mains are on and off when the mains are off, Why?

 

[wattsup]

Thanks for the input guys, anyhow after finding fault 3 hours!
Sounds easy... 25A GEC cartridge fuse blown, on the 24v maintained side of panel.

After looking at it, it does make sense, all em lights are maintained when switched on, ie when the building is occupied, if there were a mains power failure the relay would cut in and the batteries would take over, and thus switch on em lights.
There is a test button on the panel, which did work.
The fault on the fuse was strange, first checked all fuses all ok...scratch head, energise relay with screwdriver all ok, works as should. So i'm thinking no feed to relay...check fuse again now its open circuit.?

Crimped lug on feed to fuse carrier is loose, signs of getting hot..brittle cable etc.
Cuts back and recrimps new lug...check fuse again...ok, wtf?

Dodgy fuse, waggle fuse ok, waggle again not ok....dangly fuse wire within cartridg?
So I suspect, dodgy connection, overheated fuse, makes sometimes, then breaks...never seen it before.
Anyhow repairs the above all ok, ammeter on panel shows 4 Amps when em lighting maintained.

I would presume it complies with regulations, because the em lights are maintained, ie normal lighting must be on when the building is occupied, and thus switches em lights on.
If they were none-maintained I suppose the system would not comply

I once wired a cinema approx 25 years ago, i do remember all em lights were wired on a ring main in micc...but i was an apprentice and didn't take much notice, just thought about the weekend coming up all week....
I must pay more attention in the future -

 

[boatnik1]

Good show. I always hated intermittent faults. At least it makes more sense now that it's established that the Em lights come on at power outage and not go out when mains power is cut as it appeared in the original post. Presumably your pleased and your customer will be equally pleased when he gets the bill for £100 for changeing a fuse. I think this calls for a little inventiveness on the summary of the fault on the invoice. LOL

 

[wattsup]

£88.00 -;