Intercom Help!

[andyemms]

I need to call upon you experienced chaps....

I am fitting a four way intercom into some flats, never done this before and am stuck as to which is the best cable to use, Stranded or solid core?

Any help greatly appreciated.

 

[Bushy]

CAT5 cable is what we use most of the time chap and its also handy should they ever upgrade the system at a later date to require a video as it will handle that as well

 

[andyemms]

OK, I am clearly out of my depth with this one! My boss has 1st fixed in 6 core twisted pairs, stranded. He said to me today that a good friend of his has told him it probably wont work and that it needs to be solid core. I went to the wholesalers to get solid core and was told by someone that it would be fine! Argggghhhhhh. I just dont know and niether does the boss. I am happy doing all the other work for the flats but this intercom thing is all new to me....
What is the difference with CAT5?

 

[Bushy]

The main thing with CAT5 is that each of the four pairs has differing precise number of twists per metre based on prime numbers to minimize crosstalk between the pairs, so its probably one of the best cables from reducing interference (EMI)

Catch is CAT5 comes in both stranded and solid however solid is better from longer runs and so the stranded stuff for the shorter hopes between connections

Now will the system work on stranded cable - well I cant see why it would not but for sure IMHO think the best job would be with the CAT5 - pretty much all analogue intercom product are very similar, voice signals of about a volt or two are carried, direct current power rail of 12, 30 or 48 volts which uses a pair of conductors - so as long as your cable suits that, it should be okay

The other option if you're unsure is to bench test it with a piece of the cable you've installed and see if it works with the intercom you've got - if it does you know you're okay otherwise it's back to the drawing board. Either way if you play with the system at home or work at least you'll iron out any problems in the privacy of your place rather than in the common area of a block of flats - we always have a play with new equipment we are using as it allows for good familiarisation before the install

 

[andyemms]

Thanks for your help and experience. Very much appreciated.

 

[Intercomsystem]

CAT 5 is what you need, although more specifically, you can use a CW1308 cable, which is a 6 pair telephone cable.

Within all door entry kits there is a transformer The transformer which will supply 12VAC to the system. The transformer should be internally mounted, usually next to the fuse board and fed by an unswitched 3A fused spur.

All your handsets should be wired back to the door panel, take a cat5 from each handset to the door panel. The transformer runs to the door panel also - again, take a Cat5 from the transformer to the door panel. Then take the lock pair to the panel.

Hope this helps.