ECN Electrical Forum - Discussion Forums for Electricians, Inspectors and Related Professionals
ECN Shout Chat
ShoutChat
Recent Posts
Al Hildenbrand - Minneapolis - obituary
by Bill Addiss - 02/03/23 07:38 PM
Violation?
by renosteinke - 01/27/23 09:52 PM
Does NEC 551.71 (F) apply to dwellings?
by BigB - 01/20/23 10:46 AM
Power submeter connections
by HotLine1 - 01/19/23 09:09 AM
New in the Gallery:
Burger King crown sillyness
Burger King crown sillyness
by wa2ise, December 11
240/208 to a house
240/208 to a house
by wa2ise, October 9
Who's Online Now
1 members (Scott35), 21 guests, and 22 robots.
Key: Admin, Global Mod, Mod
Previous Thread
Next Thread
Print Thread
Rate Thread
#343 01/16/01 05:31 PM
Joined: Jan 2001
Posts: 2
D
don Offline OP
Junior Member
what is end of line resistor for in a fire alarm system

#344 01/16/01 06:35 PM
Joined: Oct 2000
Posts: 5,392
S
Member
supervision of the circuit [Linked Image]

#345 01/16/01 08:49 PM
Joined: Oct 2000
Posts: 5,392
S
Member
where is usually the Q... [Linked Image]

#346 01/17/01 06:45 PM
Joined: Jan 2001
Posts: 1,044
Tom Offline
Member
Sparky,

I guarantee that the resistor will be in the last box you look in, at least if you have any sense at all. [Linked Image]


Few things are harder to put up with than the annoyance of a good example.
#347 01/21/01 08:22 PM
Joined: Oct 2000
Posts: 2,722
Broom Pusher and
Member
Don,

The End Of Line [or Loop] Resistor AKA EOL Resistor is what loads the zone's loop circuit in normal operation.

The typical EOL resistor would be 2K ohm and connected to TTL logic gates. The circuit's operating voltage is like 5 VDC, so the current through the loop is 2.5 milliamps [0.0025 amps].

What this does is sets up a constant flow of current at a certain level. If a sensor trips and closes the N.O. contacts inside of it, which are wired in Parallel for each device, this causes the loop current to rise above the 2.5 Ma level and activates the alarm.

On the same note, if someone tampers with a sensor and causes the N.C. contacts which are wired in series with all devices to open, this will cause the loop current to stop flowing and will also activate the alarm. Same will happen if the loop's wires are cut.

If you need more info, let me know!! I am back from the Honeymoon and ready to write again!!

Scott. "S.E.T."


Scott " 35 " Thompson
Just Say NO To Green Eggs And Ham!
#348 01/28/01 07:32 AM
Joined: Dec 2000
Posts: 8
D
Junior Member
Your reply is correct for security alarm systems, not for fire systems. Loss of the supervisory voltage due to cut wire, missing device, etc. will give you a zone trouble, not a alarm condition.

#349 01/31/01 04:19 PM
Joined: Oct 2000
Posts: 2,722
Broom Pusher and
Member
Dandy:

Glad you caught that one! For some reason I saw Security Alarm System's EOL Resistor when I read the original question <]:-)..

I have only done Security / Burglar Alarm systems, where the EOL Resistor and the zone's loop functions as I posted. Any Fire / Life / Safety systems for the Commercial Projects we do are sub'ed out to other ECs that are familiar with the existing systems [typically Simplex], so they get all the compatable strobes, etc. and programming according to that setup.

Is the EOL Resistor's function on F/L/S systems similar to the Security system's? - To have an X value of current flowing steadilly through the loop during normal operation [functioning NAND or NOR gates will be "Inverted" (NOT Logic or Logic 0) with EOL in circuit], or do the EOL Resistors become connected when the remote device trips [alarm], which would make the logic Gates AND, OR or possibly XOR?

Any info is helpful..


Scott. "S.E.T." [Linked Image]


Quote
Originally posted by dandy467d:
Your reply is correct for security alarm systems, not for fire systems. Loss of the supervisory voltage due to cut wire, missing device, etc. will give you a zone trouble, not a alarm condition.


Scott " 35 " Thompson
Just Say NO To Green Eggs And Ham!

Link Copied to Clipboard
Featured:

Tools for Electricians
Tools for Electricians
 

* * * * * * *
2023 National Electrical Code (NEC)
2023 NEC Now Available!
 
* * * * * * *

2020 Master Electrician Exam Preparation Combos
2020 NEC Electrician
Exam Prep Combos:
Master / Journeyman

 

Member Spotlight
cookcc
cookcc
California ,Long Beach
Posts: 28
Joined: May 2007
Top Posters(30 Days)
triple 3
Popular Topics(Views)
303,226 Are you busy
232,218 Re: Forum
216,960 Need opinion
Powered by UBB.threads™ PHP Forum Software 7.7.5