Telecom line, cat5e and splitters..........

Forums › Spark New Zealand › Telecom line, cat5e and splitters..........

NZRobin

161 posts

Master Geek

# 21040 14-Apr-2008 04:16

Hi I have some questions that I hope some geeks would help me with

I read several times posters suggesting that the adsl splitter be put as close as possible to where the Telecom cable comes into the house. Is it to ensure that there is no possibility of having phones and fax machines etc connected before it or is it some other reason? In my case I would then essentially have two cat5e cables running side by side to the split point of modem and telephone. (At the moment I've got what amounts to bell cable attached to the telephone connection but am looking to rewire.) If its to ensure that there is no possibility of having phones and fax machines etc connected before it,then if you knew that wouldn't be the case, could you then use a single cable and use the adsl splitter further along the line at a more accessible location.

My second question is, as the cable coming into the house is a single pair and the cat5e is multiple pairs, could/should those pairs be 'doubled up' when connected to the Telecom line in. It just seems a wast of perfectly good cable leave them laying idle. lol!

My third question in this regard is that the cable coming into my roof space from the little Telecom box under the eves is a reasonably heavy single core loosely twisted pair of black cables. So when making the cable how do you tell which wire to connect to which? Use a digital voltmeter? Does it even matter?

And my final question is what is the best method to make the connection of these unequal size cables. At the moment the bell cable is simply, neatly and tightly wrapped around the Telecom cable then clamped down in a strip connector. Is there a better way?

Sorry for the multi questions but they were all interrelated for me. I'll put them into different threads if required.

Thanks everyone.... Robin

willnz

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# 123325 14-Apr-2008 07:07

NZRobin: Hi I have some questions that I hope some geeks would help me with

I read several times posters suggesting that the adsl splitter be put as close as possible to where the Telecom cable comes into the house. Is it to ensure that there is no possibility of having phones and fax machines etc connected before it or is it some other reason?

That is one reason, though there are several. Things like monitored alarms that are hardwired to the line, marginal improvement to line quality, etc, all come in to play.

In my case I would then essentially have two cat5e cables running side by side to the split point of modem and telephone. (At the moment I've got what amounts to bell cable attached to the telephone connection but am looking to rewire.) If its to ensure that there is no possibility of having phones and fax machines etc connected before it,then if you knew that wouldn't be the case, could you then use a single cable and use the adsl splitter further along the line at a more accessible location.

A Cat5E cable has 4 pairs. You can simply run one cable from the splitter using one pair for voice, and another for DSL.

My second question is, as the cable coming into the house is a single pair and the cat5e is multiple pairs, could/should those pairs be 'doubled up' when connected to the Telecom line in. It just seems a wast of perfectly good cable leave them laying idle. lol!

Cat5E is relatively cheap. Don't worry too much about wasting it

"Doubling up" would probably increase chances of interference and the like both in your voice and your DSL signal, so best just to use one pair for each (as above). Leave the others idle for future use such as a second line or whatever.

My third question in this regard is that the cable coming into my roof space from the little Telecom box under the eves is a reasonably heavy single core loosely twisted pair of black cables. So when making the cable how do you tell which wire to connect to which? Use a digital voltmeter? Does it even matter?

No, it doesn't really matter. So long as the same two wires that you join on to those black ones are connected to your jackpoint at the other end, your phone will work fine.

And my final question is what is the best method to make the connection of these unequal size cables. At the moment the bell cable is simply, neatly and tightly wrapped around the Telecom cable then clamped down in a strip connector. Is there a better way?

I like to use little gel-filled crimp joiners. A small version of these is available from DSE which may work, but my favoured ones are made by Computer Dynamics (available here: http://www.cablesdirect.co.nz/catalog/entry?entry=222) - make sure to get the 2 Wire one - they seem to have put the pictures the wrong way round to make it nice and confusing

These can be crimped on with standard pliers.

Hope that answers most of your questions

cyril7

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# 123329 14-Apr-2008 08:04

Hi, Will has answered all your questions pretty well, just a couple of points. The main purpose of the ADSL filter is to isolate the house wiring from the ADSL circuit. Voice and DSL run in two seperate frequency bands on the cable, common phones, faxs, analog modems etc tend to have a low impedance in the DSL band as they only concern themselves with the voice band. Hence they in effect can short out the DSL signal.

Further more normal house wiring has spurs with lengths of cable tapped off to various phone jacks around the house, this is fine at voice frequencies, however higher DSL signals see these as tuned stubs that can have all manner of ill effects on the signal. Hence the reason of placing the filter as soon as possilbe to isolate all the house wiring and have a single continuous run directly to the modem. This removal of the seen house wiring to the DSL signal is something a setup with several micro filters at each phone cannot acheive.

A secondry purpose of the filter is to remove the DSL signal from begin heard in phones faxs etc.

As Will says just use a single cat5e, use one pair for the prefilter DSL line and another pair for the post filter line for the phone/faxs etc. dont connect anything to the other pairs in the cable, just leave them safely alone.

I presume the jack where the DSL modem and phone/fax is, is the first jack, you can tap the filtered phone/fax circuit for onward feed to other jacks, the current house wiring will do that for you, whats important is that the prefilterd DSL line is now continuous from the demarc to the modem with only the filter across the line as early as possible to feed all voice jacks in whatever jumbled order you like.

Cyril

NZRobin

161 posts

Master Geek

# 123868 15-Apr-2008 22:57

(Sorry didn't mean to ignore your repllies. Broadbands been down again for the last 24+hours which is why I'm doing this in the first place)

cyril7: Snip...

I presume the jack where the DSL modem and phone/fax is, is the first jack, you can tap the filtered phone/fax circuit for onward feed to other jacks, the current house wiring will do that for you, whats important is that the prefilterd DSL line is now continuous from the demarc to the modem with only the filter across the line as early as possible to feed all voice jacks in whatever jumbled order you like.

Cyril

Wow, thanks guys, thats exactly the information that I need. Really appreciate that.
I was going to wire the house with Ethernet, coax and telephone to each room terminating at those face plates that have a connection for each, but I actually use cordless phones. The phone connection in the bedrooms were as much for future resale as anything. Are you saying Cyril that if i did wire through I'd be better to leave it unterminated at the beginning so as not to act as tuned stubs for the DSL signal. I suspect I've misunderstood that and that you are only referring to them as tuned stubs in the situation of the ASL filter placement being closer to them and the subsequent wiring having an effect. Therefor moving the filter as far up the line as possible reduces or eliminates that problem. Have i got that right?

So when I get to what is effectively the centre of my star connection to the other phone jacks I can just use the cheap white four wire cable with non twisted pairs that come in those phone jack kits? Cos I was going to run through cat5 cable to all the telephone jack points as well. Whats best practise at the star centre just crimp them all together again or should I use some sort of patch panel to isolate any future problems?

Are BT Telecom connectors still the preferred phone jacks these days. There seems to be plenty of RJ12? connectors on the end of leads these days.

Where would be the best place to get connections and tools. From the internet like http://www.cbcnz.com ? I've got all the usual places nearby. JA Russel, Next electrical, DSE, Jaycars. What should I expect to pay for a crimping tool to make these connections bearing in mind the quality I'll need, as they seem to vary quite wildly in price from place to place so that I'm not sure if I'm comparing apples with apples.

Thanks again

Robin

cyril7

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# 123897 16-Apr-2008 07:24

Hi Robin, if you place the filter as close to the entry point and seperate a clean direct feed from before the filter to the modem, then what exsist post the filter wiring will have little or no effect on the DSL signal, stubs and all.

As for rewiring the house phones adding data, wire them all with cat5e, use RJ45 jacks for both, bring them back to a common patch panel, dont delineate between the two, organise the central patch panel so you can patch either etherent or phone or both to any room jack point. Ethernet only uses two of the four pairs, so you can put upto 2 phone circuits down the same cable simultaneously if you wish, but most folk just have either phone or data and have more than one feed to some rooms.

There is an extensive thread on it here.

Cyril

willnz

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# 123905 16-Apr-2008 08:25

NZRobin: Where would be the best place to get connections and tools

I've used www.cablesdirect.co.nz many times. They've got all the cables, joiners, tools, etc - only thing they didn't have I think was BT wall jacks, but I think they did have the multi-socket type faceplates that you can put RJ45 sockets in etc.

Whenever I've ordered from them, I've received the order the next day (in one case, the same day!) - and never had any problems whatsoever.

NZRobin

161 posts

Master Geek

# 124174 16-Apr-2008 20:43

To Cyril7 and Willnz

Thanks very much to you both I'll have a look at those links now. Thanks for your patience!

I'm sure I've seen Cyril7 on other forums. DTV Forum?

NZRobin

161 posts

Master Geek

# 125314 21-Apr-2008 14:27

cyril7: Hi Robin, if you place the filter as close to the entry point and seperate a clean direct feed from before the filter to the modem, then what exsist post the filter wiring will have little or no effect on the DSL signal, stubs and all.

As for rewiring the house phones adding data, wire them all with cat5e, use RJ45 jacks for both, bring them back to a common patch panel, dont delineate between the two, organise the central patch panel so you can patch either etherent or phone or both to any room jack point. Ethernet only uses two of the four pairs, so you can put upto 2 phone circuits down the same cable simultaneously if you wish, but most folk just have either phone or data and have more than one feed to some rooms.

There is an extensive thread on it here.

Cyril

Ok I've found that the Telecom wiring coming into the roof from the demark point is actually quite long. It was bundled up under the roof tiles just over the eves so that I had to remove a tile to get at it. Now that I've found that the wiring is quite long and allows me to connect at an easier point in the roof I'm wondering if I should cut back all the excess Telecom cable and use the Cat5e cable instead. As I think I said previously the Telecom cable looks to be a heavier cable than the Cat5e but is only fairly loosely twisted.

I saw in another thread it was suggested that the in line filter could be fitted in the patch panel box which of course is a lot more convenient. Am I right in assuming that even though this may acceptable from a purely wiring point of view that putting the filter as close as possible to the demark is still better?

I like the idea of just using say two RJ45 sockets instead of a separate one for BT. My only concern is that anyone connecting to the socket wont know which is a telephone socket and which an ethernet. Do I take it from your post that each RJ45 can be wired to carry both phone and ethernet at the same time so that it doesn't matter which has a phone connected to it. If so is there a diagram somewhere that I can use to properly wire this up to the correct pins. If instead I have to use one RJ45 socket for phone and another for ethernet what does everyone use to sign these at the outlet in a tidy professional way

cyril7

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# 125404 21-Apr-2008 19:21

Yes DTV forums.

You bring up some interesting points, the standard Telecom underground or aerial leadin cable is infact quite inferiour to Cat5 for impedance characteristics due to a low twist rate. That said it is consistant and normally not seen as an issue compared to fully non twisted cables. Also dont forget that the whole multipair cable (typically 25 or 50 pairs per bundle between the switch and your front lawn) is the same loose twist cable, so in the end the improvement will be minimal.

As for placing the filter at or near the demarc or at the distribution point/panel, it is not really an problem eitherway, what is important is that the cable between the dslam and the modem is a single run with no spars, so for you to place the filter at the demarc or the panel is not important as long as there are no spars on the prefilter side.

Personally if you have a large spool of leadin cable in the roof space as you describe then I would remove most if not convienently all of it and replace with cat5. New installs specifiy two cat5e cables from the demarc to the central hub, one for 1 or 2 phone lines, the other for ethernet if oneday a gpon ONT is placed on the side of your house.

Ethernet and Phone is run on different pairs, however normally ethernet NICs will terminate the pairs used by phone such to appear to loop the line, so you wont do any damage, but the line will be looped, so you need to ensure you dont get them mixed up for any period.

Cyril

NZRobin

161 posts

Master Geek

# 125466 22-Apr-2008 01:33

cyril7: Snip...

Ethernet and Phone is run on different pairs, however normally ethernet NICs will terminate the pairs used by phone such to appear to loop the line, so you wont do any damage, but the line will be looped, so you need to ensure you dont get them mixed up for any period.

Cyril

Thanks Cyril

NIC's = Network Inter-Connects?

The interconnects affectively short out the phone line pins in RJ45 socket? This is perhaps not a good idea? :-) Guess that means my clever or in this case perhaps, not so clever, idea will have to be canned!

I think I'll follow your suggestion and cut back the excess Telecom cable to tidy things up, but I'm still having problems in finding a cable joiner for the Cat5e to Telecom cable. I need to find a joiner to take three(if I put the in-line filter close to the demark) cables of dissimilar sizes as the Telecom cable looks quite a lot larger than the Cat5e cable. I've bought some of these UY2 connectors http://www.switchedoninnovations.com.au/pdf/3MConnector.pdf but I don't think they'll take the Telecom cable even if i strip the sheathing from it. I'll get up into the roof tonight after work and measure it but just by eyecrometer the Telecom cable looks too large. I wondered whether an automotive solder terminal like these http://www.narva.com.au/Terminals_14.html would be ok? Or perhaps these 56350-56354 filled with silicone jell http://www.narva.com.au/Terminals_6.html ?

cyril7

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# 125470 22-Apr-2008 07:12

The NIC will simply short the line, not damaging anything, you will just notice the line is off the loop and sounds dead, the exchange will not be damaged nor the NIC. Typically the unused pairs in a NIC interface are shorted together and then terminated to the ground of the device by a 75ohm resistor simply to reduce any noise it could pickup if left floating. This will simply loop the line and make it appear dead, you will soon reaslise your error no damage done.

Dont cut back unused inner pairs, simply wrap them around the cable and use some insulation tape if you must to hold them so that they could be used in future, thats standard practice, dont cut them back.

I would be surprised if the scotchlocs would not take the wire, I use the 3way ones to handle the filter and line through, you can by them individually or by the box of 100 at electrical wholesalers only a few cents each. If the wire is really too thick (as per the 3M size rating) then you may need to revert to basic old screw terminals I would normally soldier the connection when making such a transistion then place in either heat shrink or normal screw terminal blocks but not doing up so tight to complete the connection, but simply to retain and insulate. Just make a short transistion length from teh inbound line to say a length of 100mm of cat5 inner wire, then use the scotch locs to attach that the onward line and the filter together.

Cyril

webwat

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# 126936 29-Apr-2008 00:09

NIC = Network Interface Controller -- actually just realised I'm not sure anymore, been a long time!! Basically its the RJ45 port on your network device.

You might end up using RJ45 for both phone and ethernet, connecting pairs 1/2 and 3/6 for ethernet and pair 4/5 for phone. If you go the whole hog and connect a patch panel for your homes resale value, you might decide to use a whole cable to each socket, so you can use each jackpoint socket for whatever just by plugging a service to it on the patch panel. If thats lost you (or more importantly your future house buyer) then perhaps its easier to just run the ethernet wires to some central jackpoints and leave the phone wiring where it is. That way you can re-cable from the demarc to a central location where a splitter is more convenient, as long as nothing else connects between your splitter and the demarc. I agree, the coiled cable would be worth eliminating but more important to isolate all the other house wiring, so put the splitter in the easiest place.

Qualified in business, certified in fibre, stuck in copper, have to keep going ^_^