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#52589 - 05/30/05 10:16 AM Fire Alarm Pull Station  
Frank Cinker  Offline
Member
Joined: Jul 2001
Posts: 311
Pennsylvania
Is it somewhat accurate to say that "in general" fire alarm pull stations are wired in series and smoke detectors are wired in parallel for non-programmable systems?

[This message has been edited by Frank Cinker (edited 05-30-2005).]

[This message has been edited by Frank Cinker (edited 05-30-2005).]


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#52590 - 05/30/05 10:53 AM Re: Fire Alarm Pull Station  
iwire  Offline
Moderator
Joined: Jan 2003
Posts: 4,391
North Attleboro, MA USA
No

Normally open non-addressable fire alarm devices such as smokes, pulls, heats etc. must be wired parallel.

Normally closed trouble indicators like tamper switches, pressure switches other panel trouble contacts etc. can be wired in series.


Bob Badger
Construction & Maintenance Electrician
Massachusetts

#52591 - 05/30/05 01:44 PM Re: Fire Alarm Pull Station  
Larry Fine  Offline
Member
Joined: Feb 2005
Posts: 693
Richmond, VA
A series circuit can be considered "self-monitoring" because a break (accidental or malicious) will have the same effect as an alarm condition.

A parallel circuit can be made "monitor-able" by using a termination resistor, as long as the monitoring panel is set up for the purpose.


Larry Fine
Fine Electric Co.
fineelectricco.com

#52592 - 05/30/05 07:32 PM Re: Fire Alarm Pull Station  
iwire  Offline
Moderator
Joined: Jan 2003
Posts: 4,391
North Attleboro, MA USA
Larry

Quote
A series circuit can be considered "self-monitoring" because a break (accidental or malicious) will have the same effect as an alarm condition.


I have never seen a fire alarm system circuit treat an open as an alarm event.

A open condition in the circuit causes a trouble.

A closed condition in the circuit causes an alarm.

A circuit with the proper resistance results in a idle panel. [Linked Image]


Bob Badger
Construction & Maintenance Electrician
Massachusetts

#52593 - 05/30/05 07:41 PM Re: Fire Alarm Pull Station  
Larry Fine  Offline
Member
Joined: Feb 2005
Posts: 693
Richmond, VA
I was generalizing, as was Frank in the first post.

Some series-circuit systems do not see a difference between an alarm condition and a line break. Opening a circuit is opening a circuit.

"A open condition in the circuit causes a trouble."
In a parallel (N.O.) circuit with an end-of-line resistor, yes. In a N.C. circuit, that looks like a trip.

"A closed condition in the circuit causes an alarm."
In the aforementioned N.O. circuit, ditto. In a series circuit, a short is a bypass.

"A circuit with the proper resistance results in a idle panel."
Ditto again.

[Linked Image] Back at ya!

[This message has been edited by Larry Fine (edited 05-30-2005).]


Larry Fine
Fine Electric Co.
fineelectricco.com


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