Alarm sounders used as time signals

[wee brian]

Hi all- BS 5839 allows schools to use the firealarm as a time signal (claus 16.1 k).

Does this happen much - or do they use different signals?

Do we think this is a good idea?

[Big T]

My school used to use the fire bell at the end of each period. 2 very short bursts at the end of a period and 2 short bursts 5 minutes later signalling the start of the next period. The fire bell when in evac was the standard long continous bell.

So it was totally different and easy to identify which one was which.

[wee brian]

Thats what it says in BS 5839 - thanks

[kurnal]

Very effective way of testing the sounders about 10 times a day- failures are likely to be reported very quickly.
But I think this arrangment is much less common since the demise of the old mains powered bell systems.
Weekly testing still required for call points though.

[Allen Higginson]

Most schools use the fire alarm system as time signals (hence the class change facility on the fire panels).They are usually activated by a Danfoss timer that gives pulsed outputs at the programmed times.
I have also seen Vigilons set up for class change timings.

[Big T]

If I remeber rightly, at my school, the hooligans tested the call points every day as well.

Obviously not to any partivular BS. Just because it was a grotty inner city school.

[Benzerari]

Do we think this is a good idea?

As far as it is cost effective, otherwise more cabling have to be run just to do the basic thing of ringing the class change bell, that the existing fire alarm system can do! isn't it?

[Chris Houston]

Hi all- BS 5839 allows schools to use the firealarm as a time signal (claus 16.1 k).

Does this happen much - or do they use different signals?

Do we think this is a good idea?

My experience (of surveying hundreds of schools in England) is that this is uncommon, most seemed to use bells for the class changes.

Don't think it's a big problem, because the class change noise is only for about a second and an alarm is more and people instantly know the difference.

[Wiz]

Using the fire bells for class-change signals is very common in many schools and as Special K (Kurnal) remarked it is a perfect way of testing that all fire bells are operating correctly, many times a day. I was stunned to find, however, that a school I visited in Kent had seperate sounders for class-change with all the additional wiring and power sources that entails (as mentioned by Benzareri) and the loss of the 'daily testing' cycle of the fire bells.
Many fire alarm control panels have a special input (often known as class-change or precinct input) that when shorted out will cause the alarm sounder circuit ouputs to operate without 'latching' the control panel or illuminating any fire indicators. Alternatively, some panels have fire zones that can be made non-latching that can be used for a similar purpose.
As previously mentioned, Danfoss Randall manufacture mains-powered timeswitches (841 = single channel, 842 = two channel) that can be connected to such inputs and be programmed to operate at the class-change times required either as a continuous output for up to 15 seconds or a 0.5S ON and 0.5s off pulse for up to 15 seconds. These models also include a control switch to turn off the signals (during holidays) or manually add extra signals for wet-weather breaks or other emergency signals. I have even seen an additional key-switch controlled 'caretaker call' button that the caretaker turns on during school holidays that visitors to the school can press to ring all the fire bells (pulsed) throughout the school so the caretaker, wherever he may be in the building, knows that he needs to return to the front door to meet the visitor.
I attended a similar school to Big T and our Latin school motto translated roughly to 'Are you looking at me? and it was therefore no surprise that voicing the school motto often led to the bigger boys using the smaller boys' faces as fire alarm testing devices!