Just how many cores for a wired burglar alarm?

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PaulUszak

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Mikefromlondon said:
wired systems use 6 core cable
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Me again. Why would systems use six cored cable? Is it for convenience, or is this just an off the cuff generalisation I've taken out of context? If it is, please disregard this question.

As I see it:-

six cores = PIR contacts + traditional tamper + power

but, considering this thread http://www.diynot.com/diy/threads/are-shunt-eol-resistors-common-these-days.461357, there are other possibilities:-

two cores = surface contacts + shunt /EOL resistors
four cores = surface contacts + traditional tamper
four cores = PIR contacts + shunt /EOL resistors + power
eight cores = smart ass active sensor with power + masking, fault, latch etc. outputs.
12 cores = for professional ??? ( http://www.electricaleurope.com/en/gb/CQR-Brown-0182mm-12-Core-6-Pair-Round-Professional-Copper-PVC-Intruder-Burglar-Alarm-Security-Cable/m-747.aspx )

Clearly there is a cable cost differential and if a job is priced lean, you might use alternate cables for different sensors within a single project. So why six..?
 
At the very least one spare pair of cables should be available for future use.

A multi core (12core, 6pair) is useful in large premises like a factory, isn't it?

Why are we going through all this, this is a DiY forum where the general public and alarm engineers look for help with the alarm they are installing or are fault finding.

I'm at a bit of a loss as to why we are having to answer questions in such detail, if you are an engineer you should be asking your boss, supervisor etc.

Perhaps I've got things all wrong, it has been a bad day today and i'm not in a very good mood I'm afraid, apologies if I've spoken out of turn.
 
No just too much time on his hands !:D
Time is money not cable , cheaper to just run everything in 8 core
 
Times I have been grateful for the extra cores for various reasons.....
 
It comes down as for what you need it to do.

8 core is pretty much used by many most of the time as its cost effective and covers most requirements with relative ease. Also be wary of what cable you buy there is some right old rubbish out there.

haven't asked about copper or CCA either.
 
I think it was a reasonable question, if it bothers you don't answer.

ps I am and so are the vast majority of people who answer here.
 
Perfectly reasonable question, Europlex. Do you have much experience? I tried to look up your profile, but you're keeping it secret...
 
I'm not an alarm engineer - but I've dabbled with them over the years for friends and family. I've just installed a decent texecom premier elite 24 with 3 keypads, 1 expander and 2 bells and even a comIP (finally got this working!!) - using nearly all the zones from a mix of PIRs, shocks, DC's etc. All wired with EOL. I've run 6 core across the house (as well as cat 6 for other kit) and thats worked really well.

I've even learnt loads about IP's (outside of DHCP's), and configuring this on the panel.

The one thing I am very thankful for is the pro's on here who give up their spare time to assist - I'm very grateful for this (and the guys at texecom tech support).

thanks guys!
 
Does any one ever select the cable on the basis of mechanical strength?

I've chosen eight core (7/0.19mm²) for the sensors /detectors, and three core (24/0.2mm²) for the bell boxes. I could have gone with thinner four core alarm cable, but I decided that it was too thin for passing around the house and especially the loft. So my decisions (based on feedback from this forum) was to make the selection on the basis of physical strength, as well as current capacity. There it is. ;)
 
Mechanical strength or current carrying capacity? Personally I use approved alarm cable 8 core. If you had an excessive length you could then double up on the cores. Metering the cables after 1 St fix would indicate if this was the case. Not sure about mechanical strength I tend to fix my panels to the wall rather than dangle them from the wire.
 
A standard core is about 0.15Ω/m. For my bell box runs, I'd drop 4.5V. Tricky with a 12V battery, hence current capacity comes into it somewhat.

I too attach my panels to the wall, but then the wiring goes under /over the loft insulation, through the garage /workshop, through the garden to the out buildings, across the kitchen wall, along the window frame and through the toilet. I just prefer my wire thick...
 
PaulUszak said:
For my bell box runs, I'd drop 4.5V.
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Why ? The bell / siren would normally be fed from a local battery continuously trickle charged ( a few 10's of milli-amps ) and held off from operating the bell / siren by a control signal ( a few milliamps at most ). The high current required for operating the bell / siren would not ( in a well designed system ) be carried by the cable to the bell / siren. The battery in the bell / siren box would be a 9 volt battery to allow 12 volts from the panel less the volt drop along the cable to still be high enough to charge the battery.

At least that is how I would arrange it.
 
PaulUszak said:
Does any one ever select the cable on the basis of mechanical strength?

I've chosen eight core (7/0.19mm²) for the sensors /detectors, and three core (24/0.2mm²) for the bell boxes. I could have gone with thinner four core alarm cable, but I decided that it was too thin for passing around the house and especially the loft. So my decisions (based on feedback from this forum) was to make the selection on the basis of physical strength, as well as current capacity. There it is. ;)
Click to expand...

3 core for the bell ?
You haven't got a clue ....have you
 
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