Wiring an alarm with Cat5 cable

[Siclark]

Hi. My electrician helpfully decided to run cat5 cable to all sensor points when I asked him to wire the house for an alarm during first fix and I only realised once it was plastered. I have just about managed to wire on the keypads and PIRs but the panel is impossible as the cores keep snapping trying to get them all into the connectors.
What do people do normally in this situation. I am thinking of a large connector box at the top of the wall where the cat5 wires come out and use connector strips to connect them to standard alarm cable and run that to the alarm panel.
If I do, could I double up some of cat5 cores that carry the power into single alarm cable cores? Or is it worth persevering with the cat5 into the panel?

Thanks.

 

[sparkymarka]

Worst case be very carefull stripping back and tin all the ends with solder ..😁

 

[Siclark]

Thanks. I should have said it's solid core cat5 hence my problems as is not very flexible. Would tin still help, although adding to the thickness might still mean I need connectors as then wouldn't fit all the wires into the panel connectors on pir power connections.

 

[plugwash]

When stripping small solid core wires you need to be EXTREMELY careful. It's very easy to accidently put a slight nick in the conductor and if you do then it will snap after only a couple of bends back and forth.

CAT5 is especially fun because not only is it solid core and very thin, IIRC it also uses PTFE insulation which is harder to strip cleanly than pvc.

Work slowly,carefully and methodically, use the appropriate sized holes proper set of wire strippers. untwist the wires first and try as hard as possible to avoid moving wires once connected.

Where you have lots of wires to one termina it's probablly easier to join them in groups first and then take a smaller number of stranded wires to the terminal, large numbers of solid wires in one screw terminal is not a great idea. Personally I'd use solder and heatshrink to join the wires.

 

[Siclark]

Yes I think my problem was exactly that, putting small nicks into the core when stripping using the double v style plier strippers. I am definitely going to join where possible in advance and as you say take stranded cable to the panel terminals. Another fun problem is that I bought the largest battery possible for the panel so have limited space to do gentle radius turns of the cat5.
Looking online I think I will use 2 16 way alarm junction boxes by the ceiling to join the cat5 to alarm cable and run that down to the panel. Taking extra care on the stripping the cable. Maybe time to invest in some new strippers too.
Somehow I managed to get thee PIRs wired without a sing let core snapping which was impressive given how little play there is with the wire.

 

[AlanE]

May seem strange question but is your CAT5 cable really CAT5?

The spec for CAT5 is for solid copper conductors but there is in existence cheap cable that sellers claim is CAT5 but the conductors are not solid copper they are copper clad aluminium - CCA.

The advert sometimes says the conductors are CCA but still refer to it as CAT5. It cannot be as it doesn't meet specifications.

Reason for asking question at start is that CCA wires are more fragile and break easier than the genuine stuff.

The same is happening with telephone cable. Specification there is tinned copper but some cheap 'telephone' wire is appearing that is CCA and also CCS copper clad steel.

Some of these cheap cables even have cores the wrong colour or pairs not twisted correctly!

 

[EightyTwo]

Use your thumbnail rather than cutters/strippers. You could also try burning it off with a cigarette lighter and cleaning up the conductor afterwards... Probably worth trying this out on a spare bit first

 

[AlanE]

try burning it off with a cigarette lighter and cleaning up the conductor afterwards... Probably worth trying this out on a spare bit first

Running individual wire in flame is also the test to see if wire is solid copper (should be) or the cheaper CCA.

If the actual wire itself melts then you have CCA and you might be better replacing it.

 

[unclebob1]

IF you have the time - and patients you could solder standard alarm wires to the end of the cat5 (found the safest way to take off the insulation is with a hot soldering iron, but it will smell!), hopefully leaving the cat5 more in tact and leaving you with softer stranded wire to play with inside the devices and panels.

 

[dmiller]

Depending on how much space you have can you use a IDC connector like these things: http://www.maplin.co.uk/p/2-way-jelly-crimp-connectors-100-pack-n72dv to connect to a cable you can strip?

(you don't strip cables for IDC connectors).

David.

 

[bernardgreen]

Next week a few technicians are going to rip out thousands of metres of so called CAT 5 or 6 cable and replace it with genuine CAT 6.

This week end looms will be created to reduce the time to install the new cable.

The stuff installed in June last year has been plagued with poor connections and appears to be copper alloy and not pure copper.

 

[AlanE]

Sounds like this cheap CCA (Copper Clad Aluminium) cr@p.

The soft wire distorts when pushed into IDC connections so doesn't displace insulation properly, and the suppliers have the nerve to say it meets specifications!

 

[bernardgreen]

The major problem with aluminium in IDC is that the joint is not a gas tight cold weld. Over time the aluminium oxidises and this continues across the contact area until the joint fails.

 

[cajar]

why is it not a gas tight cold weld bernard? is it because the aluminum cable deforms and simply makes contact rather than being 'gripped' by the teeth of the IDC?

 

[bernardgreen]

Mostly it is found that dissimilar metals do not cold weld. There are a few combinations that form a weak weld.

What is cold welding? Cold welding or metallic bonding was first officially recognized as a general materials phenomenon during the 1940s. It was discovered that two clean, flat surfaces of similar metal would strongly adhere if brought into contact under vacuum or a vacuum like environment. Cold welding is a process in which joining takes place without fusion at the interface of the two parts to be welded. Unlike in the fusion-welding processes, no molten phase is present or required to make the bond thus the term "cold" welding. Instead the metals bond by sharing electrons with each other. In a metal, groups of atoms readily `lose' electrons to form positive ions. These ions are surrounded by and share the `lost' electrons, which are responsible for conductivity. The resulting attachment of ions produced is held in place by electrostatic interactions between the ions as well as the electron cloud which is called a metallic bond. Metallic bonding is the electromagnetic interaction between delocalized (or `loose') electrons, called conduction electrons which are gathered in an "electron sea" around the metallic nuclei within the metal. Commonly understood as the sharing of "free" electrons among a `lattice' of positively-charged ions, the conduction electrons divide their density equally over all atoms that function as neutral (non-charged) entities. Metallic bonding accounts for many physical properties of metals, such as strength, malleability, ductility, thermal and electrical conductivity. Metallic bonding is mostly non-polar, because even in alloys there is little difference among the electronegativities of the atoms participating in the bonding interaction (and in pure elemental metals, none at all). Thus metallic bonding is an extremely delocalized communal form of covalent bonding. A covalent bond is a form of chemical bonding that is characterized by the sharing of pairs of electrons between atoms, or between atoms and other covalent bonds. Covalency is greatest between atoms of similar electronegativities, but covalent bonding does not necessarily require the two atoms be of the same elements, only that they are of comparable
electronegativity.

copied from http://www.quabbin.com/page2266.html