Many thanks, that's the type of info I was looking for.

It does raise another question - if 0.5mm2 is required, why is alarm cable 7x0.2 which is about 0.22mm2 ??

Robert Jenkins.

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Doesn't it mean 0.5mm diameter? 7 cores of 0.2mm dia each gives a tiny bit more cross-section than that (12%).

I thought 7 strands of 0.2mm is 1.4mm???

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That would make it bigger than 1mm lighting T&E...

0.2mm Diameter = 0.031mm2 per strand.

No false alarms from 80MHz to 1GHz at 70V/m modulated, equivalent to a 1400W uniform transmitter at 3m (10ft).

Complies with EN 61000-4-3 : 1997.

Your quite right thats a descent spec, but what about the frequencies below 80MHz..?

That would make it bigger than 1mm lighting T&E...

0.2mm Diameter = 0.031mm2 per strand.

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I was being sarcastic as where dealing in a cross sectional area again anyway.

Anyway as previously stated none of this is relevant unless your to tight to buy the proper cable.

Joking aside your cable would work, but ive never used it, and wouldnt know the actual differences in the operational state on the alarm system in the real world if you used none industry standard cable

I once read a few years ago where a NACOSS company used twisted pair for ALL runs in ALL installations and it drastically reduced theyre FA rate.

Would be a pig to work with tho!

I once read a few years ago where a NACOSS company used twisted pair for ALL runs in ALL installations and it drastically reduced theyre FA rate.

Would be a pig to work with tho!

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They must have been piss-poor in the first place to have so many false alarms to start with

One of the other threads in this topic mentions cable types & it has me puzzled.

I don't follow the reasoning on this.

In any good twisted pair data cable, the two cores in each pair will be very closely matched in length.

The normal cable used for alarm systems is fairly cheap & nasty stuff, it's nothing like the quality of a generic industrial 7 x 0.2 multicore.

or is there just a minimum specification? ,

I was specifically planning to use screened twisted pair for linking the keypads to the main unit on my new installation, so I am very curious about this!

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Did we mention regs and cable last week Cable

Jef

Did we mention regs and cable last week Cable

Jef

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Quote from that post "Think about cable! Manufacturers recommend types of cable, Not BS, so no regs, does this mean wet string is OK! "

Edited March 19, 200521 yr by DNS Security

Specs for CQR alarm cable

Core Resistance: 92 OHMS/KM

Conductor Area: 0.22mm^2

Current Rating: 1 Amp

Core Gauge: 24 AWG

Insulation Thickness: 0.3mm

Sheathing: PVC Type 1

Maximum Operating Voltage: 50v RMS

Operating Temperature: 70 degrees centigrade

Rip Cord: Yes

Screen Material: N/A

BS4737 3.3.0

Thats for FLEXIBLE connections.

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You mean door loops etc etc etc?