ECN Electrical Forum - Discussion Forums for Electricians, Inspectors and Related Professionals
ECN Shout Chat
Shout Box
Recent Posts
Tingle off the water spigot
by dsk. 10/15/18 02:36 PM
Board tester power supply?
by JoeTestingEngr. 10/13/18 12:14 AM
Voltage sag
by Trumpy. 10/12/18 06:59 PM
220/230/240V 60Hz Systems
by Trumpy. 10/12/18 06:50 PM
Linear Power Supply Quits Under Load
by JoeTestingEngr. 10/10/18 08:47 PM
New in the Gallery:
What is this for?
Plug terminals
Who's Online Now
1 registered members (gfretwell), 27 guests, and 21 spiders.
Key: Admin, Global Mod, Mod
Previous Thread
Next Thread
Print Thread
Rate Thread
Fire Alarm T Tap #161678
04/06/07 02:18 PM
04/06/07 02:18 PM
C
CRM  Offline OP
Member
Joined: Feb 2004
Posts: 74
Alberta Canada
I've got an edwards QS4 fire alarm, I've got an adressible loop going around the building, 2 wires leaving and 2 wires returning. Can I tap 2 wires off the loop at any point to feed an adressible pull station, but not run 2 wires back onto the loop. Thanks for any input.

Work Gear for Electricians and the Trades
Re: Fire Alarm T Tap [Re: CRM] #161710
04/06/07 09:21 PM
04/06/07 09:21 PM
S
Steve Miller  Offline
Member
Joined: Aug 2001
Posts: 325
Loudoun Cty, VA
The 2 back are what create the Class A system. To the best of my knowledge, no you can't. You need the 2 going back. If the 2 going out get broken the Class A will still function because it is "double end fed".

Re: Fire Alarm T Tap [Re: Steve Miller] #161734
04/07/07 07:46 AM
04/07/07 07:46 AM
R
Ron  Offline
Member
Joined: Mar 2002
Posts: 582
White Plains, NY
Depending on how far you need the circuit extension, and the size room the device is in, the NFPA 72 (FA Code) would allow you to take two cables (2 wires in each plus shield) and run to the new device. This would effectively give you the two there and the two back.

You have some limitations in this scheme if they are in the same raceway or bundle because there would need to be some separation if the area served was large.


Ron
Re: Fire Alarm T Tap [Re: Ron] #161738
04/07/07 08:38 AM
04/07/07 08:38 AM
F
Frank Cinker  Offline
Member
Joined: Jul 2001
Posts: 311
Pennsylvania
I have limited knowledge of addressable fire alarm systems. My question is aren't two wire class B system initiating device circuits more popular than the class A system? What are the advantages of the class A system?

Last edited by Frank Cinker; 04/07/07 08:41 AM. Reason: typo
Re: Fire Alarm T Tap [Re: Frank Cinker] #161742
04/07/07 10:00 AM
04/07/07 10:00 AM
R
Ron  Offline
Member
Joined: Mar 2002
Posts: 582
White Plains, NY
Class A is generally not code required, but offers better reliability during certain faults and open circuit conditions.


Ron
Re: Fire Alarm T Tap [Re: Ron] #161744
04/07/07 10:38 AM
04/07/07 10:38 AM
Y
yanici  Offline
Member
Joined: Sep 2006
Posts: 58
Atlantis
Why not just identify your"in" and "out" pairs and then run 2 pair to the new pull station. Then splice them accordingly at the junction.

Re: Fire Alarm T Tap [Re: yanici] #161748
04/07/07 11:10 AM
04/07/07 11:10 AM
D
deverson  Offline
Member
Joined: Mar 2005
Posts: 20
Mosinee, WI USA
T-taps are allowed on Simplex addressable systems. I'm not sure if there is a maximum number of T-taps per Mapnet zone. If you remove a head or a base you do get notification of that trouble. T-tapping is a nice feature for the troubleshooter because when you have to remove a base for replacement you don't end up with up to 256 missing heads. These are initiating circuits and NOT signal circuits. I've had lots of experience on 4100, 4100U panels and on hardwired in lots of buildings, installation and repair.
Dave

Re: Fire Alarm T Tap [Re: deverson] #161830
04/08/07 04:31 AM
04/08/07 04:31 AM
S
sparkydudeuk  Offline
Junior Member
Joined: Jul 2005
Posts: 8
burton upon trent ,staffordshi...
Over here in the Uk where we use addressable alarm systems, we are only permitted to take t taps off a system if it is wired in a four core and ground cable. You are not permitted to use a 2 core cable as it will not provide the recommended monitoring and re feeding of the loop if there is a fault and the isolators operate. With the systems we use, you can get an interface which you put on the loop and then wire a conventional zone with 2 cores to you r chosen area, and then it is monitored via the interface.

Nick


Featured:

2017 Master Electrician Exam Preparation Combos
2017 NEC Electrician
Exam Prep Combos:
Master / Journeyman

 

Member Spotlight
Joe Tedesco
Joe Tedesco
Boston, Massachusetts USA
Posts: 2,749
Joined: October 2000
Show All Member Profiles 
Top Posters(30 Days)
sparky 11
Popular Topics(Views)
250,265 Are you busy
187,915 Re: Forum
177,445 Need opinion
Powered by UBB.threads™ PHP Forum Software 7.6.1
(Release build 20180101)
Page Time: 0.032s Queries: 15 (0.005s) Memory: 0.9945 MB (Peak: 1.1574 MB) Zlib enabled. Server Time: 2018-10-15 21:28:27 UTC