It’s very rare!

[Kamikaze]

It’s very rare I get beaten by a fault but today’s mini adventure has baffled me. A clients fire alarm system in a commercial property drops the coil supply’s after one minute to all the lighting contactors when some of the fire alarm break glass units are put into fault. Can’t find the interface between them anywhere but it must be connected to the bell circuit. If the system is put into an alarm with the bell circuits disconnected it doesn’t do it. Also, it doesn’t do it of all break glass units, just some of them. And to top it all off, no one knows why it works that way in the first place. Why would anyone want to lose all their lights during a fire alarm anyway?

 

[tazz]

Kam is the panel addressable, and what make? the reason I ask is the matrix/logic could be programmed wrong, this would also include the sounder outputs. To cut em lighting is crazy as you have pointed out.

 

[Kamikaze]

It’s just a four zone panel. Not addressable. While I’ve been eating my tea, I have given the situation further thought. The Smart controller 4 units that control the contactors are radio linked. I’m now thinking that the sound of the bells might be causing some form of interference. This still does not explain why some break glass units trigger the system but some don’t.

 

[tazz]

This is a weird puzzle, disconnecting the bells is a small clue...only thing I can thing of now, if actual bells are used and not sirens and if the bells are old (unpolizised type) there could be interference from possible back emf from the bell coils. This I know dos not explain why only certain call points produce this situation. Only question I have now, is the radio link from the panel to the smart controller or are ther wired direct

 

[Kamikaze]

They are all bells.
Picture No 2: See the white flex on the R.H.S. into the enclosure. That is the supply from the D.B. The black cable going through the stuffing gland on the L.H.S. is going to the aerial. This set up is repeated in several locations around the building.

 

[tazz]

Can see the setup for lighting, and well designed, din rail psu powering the smart controller at 12 or 24v then switching 8 contactors in the next housing to control the lighting. I would have thaught the smart controller was used just to switch lighting off in offices or areas at certain times of the night/day, so I presume the old fire panel is switching smart controller via radio link. But now question is wheres the transmitter..?.. if conected to sounder circuit this could be the problem, would suggest if you can find, take off bell circuit and recoonect to aux relay on fire panel

 

[Darkwood]

What voltage are the bells.. do they match the alarm panel or are they 230/240 relay operated.
Its possible the coils are generating a RF signal that is matching that of smart unit signal frequency easy way to check is disconnect the aerials one by one to see if its a particular unit receiving the signal then try with all aerials disconnected ....just a thought.

 

[snowhead]

2 thoughts;

1; On the face of it, it's a crazy and dangerous way of trying to achieve something as yet unknown and should be immobilised straight away.
The last thing you want in a fire is the risk of loosing lights.

2; Is it someones "Clever idea" that when the Fire alarm is tested the E.M lights also go into test?

Also, has it always done it?
When did it start doing it?
Who installed the system, upgrades or in this case downgrades should have been documneted somewhere?
Who normally maintains the system, is it a landlords system?

I wouldn't be wasting time on finding the fault to fix this, I'd be looking for the cheapest way to eliminate the device that causes this.

 

[tazz]

Snowhead, looking at this now, I don`t think the intention of cutting the em lighting in fire condition was ment in the original design. And now the is the result of a fault which Kam is trying hard to find

 

[snowhead]

Snowhead, looking at this now, I don`t think the intention of cutting the em lighting in fire condition was ment in the original design. And now the is the result of a fault which Kam is trying hard to find

If the lighting control system is capable of causing the lighting fault whether intentional or not, it has a major flaw in it's design / installation, even if it is a fault in the fire alarm system.
I wouldn't any of it anywhere near a building I looked after or worked in.

 

[alarm man]

is it when the mcps are in fault or fire,sounds a strange one,tho regards the lighting has someone dropped a rick somewhere and its not the lights that should go out but maybe plant, door access,air con and the like

 

[tazz]

Theres a thaught Alarm man, are the smart controllers 8 ouputs just controlling lighting or are they programmmed for different uses..?

 

[Kamikaze]

Just got off the phone to the gaffer. It appears to have something to do with an electrical contractor from Weston-super-Mare. He couldn’t remember whether they installed it or whether they had a go at sorting it out. But I’m not the first spark to be defeated by it. The emergency lighting contactors are normally closed (i.e. they require a supply to the coil to open the contacts to test them). No one seems to know why they even got this lighting system. The bells are 24Vdc and those smart controllers are everywhere. It is possible that I missed one connected to the bell circuit but I doubt it, however the place is stuffed with gear and I’m not familiar with the building. But I think this will have to be the next step. To disconnect the radio links one at the time to see what happens. If I can prove it’s the radio links, then it’s a good case for removing them and replacing them with switches. It still bothers me that it only does it on some break glass units and not others. The thought that there might be a crossed switch wire that should have gone to a gas solenoid valve or a ventilation panel did cross my mind. Didn’t have time to check that out because I would have been late for my next appointment.
Anyway, many thanks for all your input guys. Much appreciated! Time for some chillaxing!

 

[alarm man]

with regards the break glasses does every one you test go into fire or do some go into fault.

 

[Kamikaze]

They all go into fire and all the bells ring regardless of which one I tested. Just the break glass by the front door and rear warehouse roller shutter door won’t trigger the dropping of the lighting contactors. The emergency lights are not affected because there is no interruption to their supply.