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Burglar/Intruder Alarm Cable

The thread about colour coding got me thinking.

Not wanting to hijack that thread though.

I was going to waffle on but determined to save you all from that.

So Burglar/Intruder alarms - hardwired not wireless.

We use 6 core alarm cable quite often but in the days before PIRs it was common to use 4 core.

Those having a set colour coding usually picked which colours were for which function and stuck with that.

Those starting their careers when 4 core was common (before PIRs were invented) had a slightly different mindset to those that started on 6 core because PIRs were already in vogue.

Anybody agree/disagree ?

 

  • ebee: 
     

    The thread about colour coding got me thinking.

    Not wanting to hijack that thread though.

    I was going to waffle on but determined to save you all from that.

    So Burglar/Intruder alarms - hardwired not wireless.

    We use 6 core alarm cable quite often but in the days before PIRs it was common to use 4 core.

    Those having a set colour coding usually picked which colours were for which function and stuck with that.

    Those starting their careers when 4 core was common (before PIRs were invented) had a slightly different mindset to those that started on 6 core because PIRs were already in vogue.

    Anybody agree/disagree ?

     

    In my day it was common to use red as positive (+) and black as negative  (-) for the 12 Volt supplies to detectors and sounders etc. and also to 12 Volt ni-cad batteries.

    Z.

  • I'd always presumed there wasn't a standard colour code for intruder alarm cabling - as that would make tampering easier.

        - Andy.

  • AJJewsbury: 
     

    I'd always presumed there wasn't a standard colour code for intruder alarm cabling - as that would make tampering easier.

        - Andy.

     

    Indeed. I was taught the same….. even to the extent of wiring each system to a random arrangement of colours but declaring this on the inside of the control panel lid.

    Although this may, at first,  seem silly, any decent alarm engineer is gonna work it out in seconds.

  • I agree, a random colour allocation is best, with a note in the control box, although any half decent alarm engineer should be able to work it out in a few seconds. If red/black is used as the supply pair, the others are fairly easy to work out in order to bypass a sensor. 

    Regards,

    Alan

  • Yes indeed that was one idea a few years back known as extra security but I rarely saw it on my jobs. Other installers often stuck with their own codings throughout installations and from one install to another . Many had similar, if not the same scheme.

    The reason I asked the question is that I often found two schools of thought. This depended largely on whether the installer started as a 4 wire person or a 6 wire person although some of the 4 wirers changed as they became six wirers over the years.

    Here is what I observed:-

    Before the advent of PIRs etc it was basically 4 wire. Two loops. One alarm loop for contacts etc and one antitamper loop  . All using normally closed devices such as door contacts (magnetic reed switches) or microswitches. 

    However pressure mats were normally open devices and were wired to join the two loops together when stood upon.

    Two pairs of colours were selected for A alarm and B antitamper functions. Often Red and Black were chosen as one loop because they were both single phase and DC colours?

    Progress to PIRs and an extra two colours were present and they were then used for +ve & -ve supplies to the PIR detector.

    Some installers stayed with that preference but a few changed.

    Installers coming up thru the PIRs route often started with Red & Black for +ve and -ve supplies respectively then chose the remaining 4 conductors for their two loop approach.

    Off course they might be joined to 8 core, 12 core or even 20 core. I have not seen 20 core for many years though. 

    I`m sure that many installers will agree with something broadly similar to what I`ve said but then again I suspect that many might disagree too.

    In many cases the two loop system was replace with ID “Biscuits” then Zone resistors both of which freeing up some conductors for other uses and increasing security. Then wireless and icloud based systems.

  • ebee, now you have just told the burglars which wires to cut! ??

  • cut any and get an alarm activation. join wrong ones and get an alarm activation. Russian Roulette ?

  • 6 core alarm cable is used for sensors in two ways:

    1. One pair for power, one pair for sensor, one pair for antitamper.

    2. One pair for sensor 1, one pair for sensor 2, one pair for antitamper – if both sensors are unpowered.

    4 core cables are still used for unpowered sensors. 8 and 10 core cables are also available for connecting multiple sensors.

    Some sophisticated sensors, such as IR beams, may require cables with more than 6 cores. 

    There are also the cables connecting the siren, remote keypads, and autodiallers to the main control unit.

    The colour code is not standardised nationally but is usually standardised by alarm installation companies. Burglars have taken advantage of this!

    Genuine alarm cable is manufactured to BS4737-3.30:2015. It must be used for the installation to comply with with BS4737. The use of telephone and ethernet cables is no longer acceptable although they are still commonly used for DIY installations, and by some electricians and telecomms technicians who have added burglar alarm installations to their repertoire of services.

  • I`m not aware of 10 core as a bog-standard one

  • The relevant standard, as has been pointed out, is BS 4737-3.30:2015 Intruder alarm systems. Specifications for components. Specification for PVC insulated cables for interconnecting wiring

    Clause 6.1.1 confirms there is no accepted standard colour code for the cable itself, and therefore there can be no accepted standard code for the use of the cable:

    6.1.1 General
    The cores shall be distinguishable, for example by colour or striping.
    Conformity shall be checked by visual examination.

    Only the rip-cord cas a confirmed colour-code according to Table 2:

    • Green: LSHF 100 ohms/km per conductor at 20 degrees
    • Red: PVC 100 ohms/km per conductor at 20 degrees
    • Yellow: PVC 155 ohms/km per conductor at 20 degrees


    Cables to the standard should be used for a maximum voltage of 50 V (although the standard does not specify AC or DC I would assume DC given the primary application).

    The Standard includes installation guidelines in Appendix A … and reference is made to BS 7671 as the primary standard. Minimum bend radius = 6 x diameter of cable