Fire alarm

[the pict]

Hi All, should a sounder circuit be between 6&8 Ohms and detectors the same, even if it's done in 1950' pyro, also should I get a difference in mA's on sounders and detectors between L&N L 2mA N .5mA, if I find a resistor in a head is that the end of line, I have a missing head with resistor in the holder is this a bypass or is it end of line sorry if this is a bit glib as I am having a mid life crisis,
Pict

 

[Jay Sparks]

Hi Pict,

Not sure about the testing side of it, as I normally leave that to the fire tech guys but yes, the resistor useually means E.O.L.

Jay

 

[telectrix]

if there's only 1 cable in the box, then it's EOL. sssimplesss

 

[the pict]

So in the holder with the missing head with the resistor if I link out the terminals for the head the "fault" should clear, any one know if the resistance of alarm cable "the red stuff" is the same as old pyro and are all heads standard
Pict

 

[telectrix]

different makes are different. if a head is removed, there's a diode across 2 teminals that fools the panel into thinking the head is still there, first thing i would check is the volts at the box. if it's a detector circuit, you should have 24V. if it's a sounder circuit, should only have volts when panel is in full fire alarm.

 

[the pict]

Thanks Tele in the holder with the missing head there is what I assume is the EOL resistor in a black encapsule but nothing else although the fault lights are general fault and sounder 1, it is a MAG 2 so I think I may get a new head and holder complete
Pict

 

[telectrix]

sounds like ( pun intended) that it's a sounder circuit. as i said, check d.c. volts at head to confirm. the eol device may be a mix of resistor/capacitor. if a pure resistor it will be generally between 1k and 6.8k ohms.

 

[the pict]

Do you mean at the sounder head for DC V or at the sounder panel terminals I suppose both would do no harm ??? I have ordered a new head and base and a call point as one had got water damage
Pict

 

[telectrix]

at the panel you should have permanent 24v d.c. on the zone terminals. same at each detector. for sounders, you need to put the panel into "fire", then check for 24v at sounders.

 

[the pict]

Thanks Tele normally I do'nt do these as you probably have guessed but its my pub landlord and I have done a load of work for him so I do'nt like to knock him back thanks for your patience
Devlin

 

[polo1]

I'm probably going to get a -------ing for saying this, but I would strongly recommend not working on life critical systems unless you are competent in that particular sphere. I appreciate you are trying to do a favour, but you'll get no thanks in front of a FAI if there's a fire and somebody gets killed. I don't mean to be over dramatic, but I've been directly involved in such a scenario and believe me it ain't pretty (for you or anyone else).

By all means get quals and experience, but meantime don't take the risk!

 

[alarm man]

i think you have 2 faults,the head i presume is a detector head that looks like the eol has been placed across the pair hence why your getting no zone faul with the head removed ,the sounder fault could be many things,you need to meter the sounder circs from the panel,10k eol for sounders.

 

[the pict]

Polo yes you are absoultly correct and I intend to do so, and no one here will decry you for your concerns quite the opposite I imagine,
Pict

 

[the pict]

so the sounder has a eol resistor or is that 10K measured at the sounder reading through the alarm panel and back, the head is on order to cure that side of things
Pict

 

[alarm man]

so the sounder has a eol resistor or is that 10K measured at the sounder reading through the alarm panel and back, the head is on order to cure that side of things
Pict

10k resistor in last sounder,if a head had been removed due to false alarms,you may find the sounder has been too,if its a pub/club check the sounder in the stewards flat if it has one might have been dissed, try finding a sounder with 10k then work back,otherwise just check continuity from the panel to the first sounder then to the next etc

 

[the pict]

Right got it and I have just realised there is 2 sounders on 1 circuit so it starts to make sense also it helps if you forget its an alarm and work as if it were just another circuit
Pict

 

[REIBURN]

hi all iv started working for a new company as an electrician but they have sent me to try and fault find on a commericail fire alarm. theres a fault on zone 3 but its intermittent. i have never done work on alarms before but the boss says that they are easy. iv been back 2 times and cant find the fault any ideas how to go about fault finding on an alarm system?

 

[tazz]

Presume this a convetional panel, intermittent faults can be a pain, but your looking for an o/c or a short to give zone fault 99% of the time its going to be o/c ie loose connect on device. 1. put the end of line unit back in zone to test the control no fault panel ok. 2. start test the voltage on each device on the incoming only ie L1 in and L2. should be 24-27v. 3 check connections on that device. then replace and move on to next. 4. continue intill you find a device with no voltage. This is now the point were there is and o/c from the last device you tested to this one. So now you have a location check devices again, check for junction boxes, and cable damage. Hope this helps