Alarm Circuits Guide

By: IPVM, Published on May 09, 2017

Alarm circuits are a fundamental element of wired burglar systems. Designing the alarm circuit greatly affects its performance. In particular, more efficient circuit designs introduce less resistance and cause fewer false alarms. In this note, we examine:

Alarm Circuits Overviewed

  • ******** **********
  • *** ** ***** ******* Works
  • ***** ** ******* *** Circuit ********
  • ********* ** ********
  • *****
  • ***** *******
  • *** *******
  • ******* ********** **************
  • ******** ** ******
  • ********* **********
  • *** **** ********** ** Too ****?
  • *** **** ******* ** Too ****?
  • ***'* ***

***** ******** *** ***** between ** ***** ***** and ******* *******. **** the ******* / ********** of ***** ***** ** broken (*.*., ** ******* window *****), *** ***** is ********* ** *** system ** ***** / enabled.

How ** ***** ******* *****

** ***** ******* ******** of * **** ** wires ******* **** ** alarm ***** ** * sensor, **** ** * magnetic *******. ********** ****** flows **** *** ******** terminal, **** *** ****, and **** *** ******. When ********* ****** *** sensor ** *****, ** completes *** *******, ******** the ****** ** **** down *** ***** **** and **** ** *** negative ******** ** *** panel.

** *** **** ** the *******, *** ******* is ******** ******* *** magnet ****** *** ***** to *****, ******** ******* to **** **** *** reed ** *** ******** side ** *** ******* to *** **** ** the ******** ****.

***** * **** ** wires ** ******* **** sides ** *** ****** to **** ********* ** the ***** ******* * large ******, ***** ** where *** **************** ****. *** ********* flow ****** *** ****** this *******, **** *** positive ******** ** *** panel, ******* *** ******, and **** ** *** negative ********. ******* *** window **** ***** *** reed ** ********, ***** will ***** *** ****** and **** *** **** of *********. ** ***** words, ******* * ****** will ****** ****** *******. ** ** **** open ******* **** ****** an ***** *********.

Loops ** *******

*** *** **** ****** ways ** *** ******** sensors ** ******** ** to *****************.

***** *** ********* ******* it ******* * ***** pathway, ***** ***** **** resistance, ***** ****** ** failure *** ****** ** install. *******, ***** *** only ********* ** **** in *** ************ ***** the ********** *** *** ability ** *** ***** and ***** ******* *** window ****** ****** *** drywall ** *********. ********* requires ************ **** *** general ********** ** *** carpenter. *** ***** ******* needs ** ** **** to ******** * ********** to ******** *** ****** before *** ******* **** is ********* ** ***** installing *******, *** *** carpenter ****** ** **** where ** ***** ***** on *** ******** ** window *****.

******* ****** ** ********* because **** *** ********** and *** **** **** consuming ** *******. *******, adding ****** ** ******* homes ** ********** ********* require **** ***** ** is *** ******** ** open *** ******** ** run * ****** *******.

*** ***** ** ******** exists: ***** ****** *** ITB (**-***-***) ******. *** benefits ** ***** ******* are ***** ***** ******* resistance *** ***** **** wire, *** ** ******** a **** ******* ********** to **** *** ******. By ********, *** ******* are ****** ** ************, have ***** ********* ****** of ******* *** **** can ** **** ** a **** *********** *********, but **** **** ****** total ******* ********** *** require ** ********* ** home *** * **** to **** ********** ******.

Loops *********

*** ***** ***** ***** an ******* ** * loop **** ****** *** windows ** ***** * circuit. ******* ****** *** top **** ** *** bottom **** ** ****** the ***** ****** ** left ****** **** ***** the **** **** ** open. ** ********** ****, a ********** **** * single **** **** *** contact ** *******, ******** the ******* ** ****** around *** ******* ** a ******. *** ********** leaves * **** ** every ******, ***** **** bring *** ******* ** one **** ** *** contact *** *** *** other.

*** **** ** *** pair **** ** *** window ** *** *****, and *** ***** **** to *** ****** ** the ****. *** ********** has *** ***** ** wires **** *** **** of *** ******* ** the *****. *** **** of *** ******* ** the *** ***** ****** has * **** ******* to *** **** ** the ******* ** *** left (***** ** ***** below). *** **** ******* the *** **** ******* and *** ****** **** contact (***** ** *** below) ********* *** ******, as **** ** *** the ******* *** ******.

Field *******

* ***** ****** ** one **** ** **** at *** ****** *** of *** ****, ******* at *** ****** ******. A ******* ********** *** make * ***** ****** if *** ********** *** right. ******* **** ** accessible *** ****** ***************, so * ***** ****** can **** ** **** if ***** ** ********* to **** **** **** from ****** ****. *** example, **** ****** *******, a ********** *** ****** the **** ** *** underside ** *** ***** or ********, *** ** sight *** ****** ***** by ** *********** ***** troubleshooter. ***** ********** ******** wire *** ****** *** strobes ** * ******** to * ****** *******, and **** ***** ******* inside *** ***** ***.

** **** *******, * pair ** ***** (*****) is ******* ** *** alarm *****. *** ***** are ******* ** ******** contacts ** *** ****** sash *** *** *** sash ** *** ***** window, *** **** ***** are ******* ** *** top **** *** *** bottom **** ** *** left ******. *** *** wire ** ******* ** one **** ****, ******* one *** **** *** one **** **** ** be ******* ** *** green *****.

ITB *******

*** *******, ****-***-**********, *** ***** ********** *** ***** ***. ******** ***** *** run ** **** ********** contact, *** **** *** then ****** ** ** the ***** ***** * splice.

*** ******* *** **** easier *** ************* ***********, and **** ****** ** wire **. ****** *** splices, *** ***** *******, to *** *** ******* to **** *****, ** faster **** ****** * splice ** ***** *********** and **** ******** *** how ** **** **** away. **** *** **** much ****** ** ************ if ******** ******* ** the ***, ******* * troubleshooter *** ******* ******* the ******* ****** ******* the *****, *** **** not **** ** ***** find *** ******** *** splice. *******, ******* ********** wires ** **** **** labor *********, *** **** more ****.

Circuit ********** **************

*** ******* ** ** alarm, ********* ********* ******* such ** ********, ******* a ******** ****** ** charge ******* ******* *** wires ** * ******** speed *** ******** ** it **** *** ****.

***** ******* *** * voltage, *******, *** ********** value:

  • ******* ** ******** ** volts (*).
  • ******* ** ******** ** amps (*).
  • ********** ** ******** ** ohms (Ω).

********* * *********** ** how **** *********** ** available *** ***. ***** device ***** *** ****** of ******* ** ******** to *******.

  • ** ***** *** *** volts, *** ****** **** either *** ***** ** or **** **** ***********.
  • ** ***** *** **** volts, ** **** ****** shut **** ** ********.

********* *** ******** ** which *** ****** *****. All ******* *******, ******, *********** ** * predetermined ****.

  • *** ****** **** *** cause *** ****** ** work ****** ** **** voltage, ***** ***** ***** it ** ****** **** down, ********, ** **** erratically.
  • *** **** **** ** not ******* ** *** device ****** **** **** current **** ** *** use.

********** ** ******** **** slows *** *******. ******* that ******** ********** ***

  • ****** ** ********* *******
  • **** ******
  • *******
  • ****
  • ****** ***********

*** **** ********** ** a ******* **** ***** the *******, ****** ** more ********* *** *** alarm ** ******* *** zone ********. ***** ********** increases ** *** ******** as **** **** **, improperly ******** ******** **** a **** *********** ** causing ***** ****** ***** after ***** *********. *********, every ****** ****** ** made ** **** *** resistance ** *** ** possible.

Parallel ****** ******

*** *** ******* ** joining ******** ******** ** a ****** ******* *** parallel *** ******. ******* can ****** ** ******* ************ ********** **** *****. ******** using ******** ******* *** called ******** ********, *** circuits ***** ****** ******* are ****** ****** ********.

** ******* ******, *** ** *** pair ** ***** ** spliced ** *** *** next **** **. **** way, ** ****** *** many ***** ** ***** are *****, *** *** result ** *** ***** that *** ****** ** connect ** *** ***** terminals. ** *******, **** of ***** *** ******* to **** *****. **** makes *************** *******, ******* a ********** *** ****** test * ****** ****** of *** ******* ** a ****. ****** ** typically **** *** ********** a ***** ****** ** devices ** * *******. It ** ****** *** easier ** **** **. The ******** ** **** series ********** * *** more ********** ** *** many ******* *** *********.

** ******* *******, *** ***** **** each ****** ** *** circuit **** ** ******* together ***** *** ***** not ******* ** ******** are ****. ***** ****** conductors **** ** ********* to *** ***** *********, while *** ******* '****' in *** ***, *** connected ** ******** *** each *****. ** ****** how **** ******* *** wires *** ********* ** the *******, ***** **** always ** **** *** wire ** ******* ** the ******** *** *** to ******* ** *** negative.

******** ********** ********* **** *** connecting * ***** ****** of ******* ** * single *******, ** *** circuits **** **** **** of *****. ** ******* reduces *** ****** ** resistance, ******** ***** ***** numbers ** ******* ** be *********. *******, ** is ****** / **** complicated ** *********, **** not **** ** **** incorrectly, *** ** **** difficult ** ************ ***** on.

** * ******** *******, all *** ******** ***** of *** **** ***** are ****** ******* ********, with *** *** ****** being *** ***** **** twists. **** *** ** a ********* ** ******* to ***** *********. ** order ** ************ *** wire ***** ** * branch ** *** *******, a ********** **** ***** undo *** ****** ******.

*********** ***** *********** ******* a '****' *** **** to ****** ******* ** parallel *** **** ** splice ** ******. *******, the *** *********** ** this: **** * ****** splice **** ****** ** too **** **********, * parallel ****** **** ** used. ****** ******** ********, technicians *** **** * circuit ** ***** ** determine *** ****** ** resistance *******.

Measuring **********

********** ** ******** ***** a ******* **********, ** DMM. ** ******* **********, turn *** ******** **** of ***** ** *** Ω (****) ******, *** touch *** ***** ** the **** ***** ** the *******. *********** ******* resistance ** ***** **

  • **** **** *** ******* on * ******* *** functioning ********
  • ****** ******* ** **** devices ** * **** or ** ***** **** up ***** ******** *****
  • ****** ******* * ******* should ** ***** ** series ** ** ********
  • ****** * ******** ********** at *** **** ** installation
  • ************, ** * **** with * ********** ******* well **** ******** *** indicate * ****** **** or ********* ******

How **** ********** ** *** ****?

***** ** ** ***** answer ** *** ******* amount ** *******, *** consequently *** ******* ****** of **********, **** ****** be ********* ** * single ********* *******. ** a ******* **** ** thumb, **** ********** *** to **** *** ******** resistance ** * ****** circuit ** ~**Ω. ******** that *** ********** **** inevitably ***** ** **** time, ********* ** *** number *** ****** ** sensors ********* ** *** circuit, *** ****** *** nature ** ******* ** the ****, *** ***** composition ** *** ****, and **** *** ***********, which ***** ***** *** wire ** ******* ****** or ******. *** ********* animation ***** *** ******* slowing *** **** ******* are ***** ** *** circuit:

********* ***** ***** ************* have ********* ********* *** what *********** ** ***** condition, *** *** ***** standards *** ***** ** the ***** ******* *** resistance ** * **** circuit. ** * ******* has * ******* ************* higher **** **Ω, ******** either ***** * ******** splice ** ********* *** zone, ******** **** ******* from *** **** *** wiring **** ** * new ****.

**** ********** ****** *** splices ******* ** ****** them ** ****** ** split *** **** ***** on. ** ******* **** been ***** ******** ***** wire ***** ** ***** splices, **** ** *** possible.

How **** ******* ** *** ****?

** ******, ** ********* can ******* *** *** doors ** * ****** zone, *** *** ******* on ******* ****, *** the ****** ********* ** a ***** ****, *** so *****. *******, **** is ***** ** *********** way ** ***** ** alarm. *** **** ******* are ** * ****** zone, *** ****** ** will ** *** *** user ** ****** *** which ****** ** ******* the **** ** ** open.

** *** *** ******* in * **** *** on * ****** ****, the **** **** **** to ***** *** ** them ****** ***** **** to *** *** ******. If * **** ***** to **** * ****** window **** ***** ****** the **** ** *** system, **** ***** **** to ****** *** *** windows ** *** ****, which ** * ****** security **** **** ****** bypassing * ****** ******. If ******* ******* ***** to ******** ****** ** fire ** *** ****'* site, **** **** **** be **** ** **** a ***** *********** ** the ******** ** *** problem, *** * ******** location.

**** ****** *** **** handle * ******* ****** of ***** *** ** the ***. ***** ********** zones ******** ********** *** installing **** *********, ***** add ** *** ******* cost ** *** ************. Using ******** **** ********* may ******* ****** * second ***, ***** ******** adds ** *** ****. The ******** ** **** to ******* ******* ** a ****** **** *** when ** ******** ******* into ******** ***** *** no **** ******, *** becomes ******* **** **********.

Wiring ******

****** ****** ** ******** different **** ****** ***** alarm *******.

  • ****** *** ***** ** watts, *** ***** **** all ***** ***** *******
  • ***** *** * ******* of *** **** * power * *************
  • ***** * ******* ** how **** ***** * device****
  • **** ****** *** ***** to ** *****

**** ****** **** **** a ****** ***** ******. However, **** ************ **** for *** ****** ** be ***** ** **** sirens **** ** ******. For *******, * ***** mounted ******* ***** ***** hearing ****** ** ******** at * **** *****, but ***** ** ********* for ************ ********. ** order ** **** ********* volumes **** * ****** output, ********** *** ****** to **** ****** ** either ******** (*** ****** volume) ** ** ****** (for ***** ******). **** can **** ****** ** wire **** ****** ** parallel *** ***** ****** in ******. *** ****** in ****** **** **** resistance **** *** ****** in ********, ** **** there ** **** **********, and ********* ***** *****, forcing *** ***** ** sound ** * ***** volume.

***** ***** ****** ** a ******* ************ ** Ohm's ***.

Ohm's ***

************* ***'* *** ***** alarm *************** **** ******. Ohm's *** ****** **** there ** * ****** relationship ******* *****, ****, and ****, ************ **** volts ****** **** ***** ohms. **** ** **** divided ** *****, *** ohms ** ***** ******* by ****. ****** ********** (ohms) ***** *** ******* (amps) ** ****, *** adding ******* (****) ***** the ********** (****) ** down.

*** ******** *** ** lowering ** ******* *** power ********* ** *** siren ** ** ******* or ******** *** **********. This ****** ** ****** the ****** ** ********* power, ***** ** **** affects *** ********* ** the *****.

************* ***'* *** *** help * ********** ******** and ****** ***** ********, sensors, ********, *** *******. Changing * ****** **** series ** ********, ********* a ***** ****** *** one **** ******* *** same ******* ** * higher ********, ** ****** a ******** *** *** repair ******* **** ** installer *** **** **** understand *** ***'* *** works.

Comments (9)

Nice GIFs! Good Read.

Nice report

Now let's start describing the various circuit types.  Class A, Class B, Style Y, Style Z

Thanks, very informative 

Next wil nice too read about EOL resistors, resistor guide 

how to change resistance using more then 1 resistor parallel or series 

 

I'm quiet surprised how the DEOL not came to the picture in this article. DEOL is only 2 wire for a zone, which is really helpful if you plan a system, and its wiring.

One sensor --> One zone. In the past 15 years I have never broke this rule. Many times the cheap series makes hard to find a contact issue caused alarm, and many times the junction boxes tamper switchs can cause sabotage fails. So this is the really-really basic, and never ever use paralells or series. Especially that zone expanders are cheap as hell. :)

 

I fully agree that a single device on a single zone is the simplest and best design. However, it is not always practical, it is not always possible, and, due to the large base of installations that have not followed this principle, it is important for installers to understand multi-device circuits in order to troubleshoot them. 

First, it is not always practical to dedicate a single zone to every single device when you have a large number of devices clustered together. For example, say you've got a bank of double hung windows, like this:

You could run six wires and dedicate six zones to each contact, but it would be far more practical for the installer and far easier on the user to dedicate a single zone to the contacts (and one more for the acoustic glassbreak detector). This way, the alarm user would have to check to see if one of the "dining room windows" were open instead of having to remember which window was number 39, or what have you. 

Second, it is not always possible to dedicate zones to every single device. I've been installing alarms in homes since well before zone expanders were cheap or even available, and even today, not every panel can accommodate enough zones to dedicate a zone for every device. The Vista 20P, for example, can only accommodate 48 zones- more than enough for a small home but not quite enough for a large one.

I'm having a difficult time estimating the 'average' number of windows in a house, but this website for window washers suggests that the average 3,000 square foot house has 30 windows on average, which sounds about right to me. If those windows are double hung, that's 60 magnetic contacts, not including glassbreaks, motions, or doors.

I'm aware that larger panels exist, but they are more expensive than the smaller ones.

Third, even if you try and dedicate zones today- which, again, is always the best way to go, if possible- there is an enormous number of alarm systems installed and in place that were designed before zone expanders were common. Therefore, it is necessary for an alarm technician to know and understand how to troubleshoot these older systems, which in many cases are still functional and still generating RMR in the form of a monitoring contract. 

Fortunatelly here in Europe, we don't have these "nightmare" type windows :) So 1 magnet can do the job for us. But in this case, I again miss the DEOL, and with a junction box (even hidden) this can be done at the window side, and the zone is secured (from sabotage) and can give signal, via 2 wire only.

In the old days, we many times offered Galaxy 60 panels for larger homes, and in one case we deployed an 512, it was so huge. Nowdays here we have several very nice "low budget" high capacity 64-128-256 zone alarm panels here, and there is solution as well to handle them within a network. A 64 zone panel is around 100USD, with 16 zones onboard, and with really advanced features. If you want this in EN 50131 Grade3 its 150USD. The 256zone brother is around 200USD. So really don't need to think too much about, how you resolve an issue like you mentioned above.

100% could not agree more, you hit the nail on the head Sir.

As a former service technician working on equipment installed in the 80's having multiple devices on one circuit is quite aggravating when trying to troubleshoot false alarms, especially the old window bugs or window foil. Now when systems were installed back then, say the Moose 735/235 there wasn't much choice. In this day and age their really is no excuse for having more than one device on a zone other than say a double door. Zone expanders aren't that expensive and wireless is extremely reliable these days especially the battery life. I installed my first residential system in over 10 years last summer for one of our good commercial customers and I hardwired everything except for the windows. Man what a pain in the arse. The house was only 75% gutted so the prewire was a nightmare as the house had no real chase between basement and attic and the fact there was not air conditioning and it was over a 100 degrees that week. My point is everything was wired separately as I didn't want the next technician to come out when a glass break started falsing and have to figure out which one it was on a circuit of 10. Also I put the EOLR's at each device as well. I will say after doing commercial work for so many years this was my best looking panel install I ever did thanks to some Panduit. Also with the new low current sirens out there really is no need to use speakers and a siren driver anymore either. Good knowledge for those who don't know how to series parallel though. Anyways just my two cents.

Read this IPVM report for free.

This article is part of IPVM's 6,536 reports, 881 tests and is only available to members. To get a one-time preview of our work, enter your work email to access the full article.

Already a member? Login here | Join now

Related Reports

Exit Devices For Access Control Tutorial on Aug 25, 2020
Exit Devices, also called 'Panic Bars' or 'Crash Bars' are required by safety...
Door Fundamentals For Access Control Guide on Aug 24, 2020
Doors vary greatly in how difficult and costly it is to add electronic access...
Forced Door Alarms For Access Control Tutorial on Aug 17, 2020
One of the most important access control alarms is also often ignored....
Drain Wire For Access Control Reader Tutorial on Sep 23, 2020
An easy-to-miss cabling specification plays a key role in access control, yet...
Uniview Deep Learning Camera Tested on Jul 14, 2020
Uniview's intrusion analytics have performed poorly in our shootouts. Now,...
HID Releases VertX Replacement Aero on Aug 10, 2020
HID is replacing two established and broadly supported types of access...
Vehicle Gate Access Control Guide on Mar 19, 2020
Vehicle gate access control demands integrating various systems to keep...
Remote Network Access for Video Surveillance Guide on Jul 27, 2020
Remotely accessing surveillance systems is key in 2020, with more and more...
AHJ / Authority Having Jurisdiction Tutorial on Aug 06, 2020
One of the most powerful yet often underappreciated characters in all...
Dahua Buenos Aires Bus Screening Violates IEC Standards and Dahua's Own Instructions on Jun 30, 2020
Dahua has promoted Buenos Aires bus deployments as "solutions that facilitate...
The Future of H.266 For Video Surveillance Examined on Aug 17, 2020
First H.264, now H.265, is H.266 next? H.266 was recently announced amid...
Verkada Falsely Claims "First Native Cloud-based Access Control and Video Security Solution" on Jun 18, 2020
Verkada's false claims continue, this time to be the first native cloud-based...
Free Online NFPA, IBC, and ADA Codes and Standards 2020 on Sep 03, 2020
Finding applicable codes for security work can be a costly task, with printed...
The Insecure Verkada Access Control System on Jun 25, 2020
While Verkada touts the security of its system and that how their new door...
LSP Presents 2nd Generation FP Power Supplies on Apr 29, 2020
Life Safety Power (LSP) presented its FP2 power supply in the April 2020 IPVM...

Recent Reports

New Products Show Fall 2020 Starts Tomorrow! on Sep 27, 2020
Tomorrow, IPVM's sixth online show will feature New Products from over 25...
OnTech Smart Services Partners With Google and Amazon To Compete With Integrators on Sep 25, 2020
A pain point for many homeowners to use consumer security and surveillance is...
The Future of Metalens For Video Surveillance Cameras - MIT / UMass / Immervision on Sep 25, 2020
Panoramic cameras using 'fisheye' lens have become commonplace in video...
Hikvision Sues Over Brazilian Airport Loss on Sep 24, 2020
Hikvision was excluded from a Brazilian airport project because it is owned...
China General Chamber of Commerce Calls Out US Politics on Sep 24, 2020
While US-China relations are at an all-time low, optimism about relations...
Verkada Disruptive Embedded Live Help on Sep 24, 2020
Call up your integrator? Have someone come by the next day? Verkada is...
IP Networking Course Fall 2020 - Last Chance - Register Now on Sep 23, 2020
Today is the last chance to register for the only IP networking course...
Drain Wire For Access Control Reader Tutorial on Sep 23, 2020
An easy-to-miss cabling specification plays a key role in access control, yet...
Norway Council of Ethics Finds Hikvision Human Rights Abuses "Ongoing" on Sep 23, 2020
Hikvision's involvement in "serious human rights abuse" in Xinjiang is...
IPVM Camera Calculator User Manual / Guide on Sep 23, 2020
Learn how to use the IPVM Camera Calculator (updated for Version 3.1). The...
Installation Course Fall 2020 - Save $50 - Last Chance on Sep 22, 2020
This is a unique installation course in a market where little practical...
SimpliSafe Business Security Launched Examined on Sep 22, 2020
SimpliSafe has launched "SimpliSafe Business Security" that the company...
FLIR CEO: Many New Fever Entrants "Making Claims That The Science Just Won't Support" on Sep 22, 2020
FLIR's CEO joins a growing number calling out risks with fever / screening...
China Bems Temperature Measurement Terminal Tested on Sep 22, 2020
Guangzhou Bems (brand Benshi) is the manufacturer behind temperature...