tel cables and CAT6

[CharlieB1981]

renovatng a house and taking the oportunity to install new sockets in most rooms for network and phone.

couple of questions:
1)i have some cat6 network cable left over, is this ok to use for phone sockets, plan is to have a splitter at the main box to separate the line to the different rooms (about 4 in total)

2)the BT line at the front of the house has been cut at some point where it enters the house, but there is a junction box on the front of the house linking to the telegraph pole, am i ok to repace this wire and reconnect to the junction box or do i have to pay the extortionate cost for BT to do this?

thanks everyone

 

[bernardgreen]

CAT 5..7 cable is OK for telephone signals ( voice, ringing dialing etc ) but will reduce the ADSL signal so use telephone cable for the circuit carrying the ADSL signal. Use an NTE 5 with a filtering face plate to separate phone from ADSL at the BT master socket.

 

[RickMoore]

Better to plug in the router at the master point, then use Cat6 to run to network points and/or a switch than plug the router in on an extension.

 

[ironsidebod]

CAT 5..7 cable is OK for telephone signals ( voice, ringing dialing etc ) but will reduce the ADSL signal so use telephone cable for the circuit carrying the ADSL signal. Use an NTE 5 with a filtering face plate to separate phone from ADSL at the BT master socket.

Why would UTP Cat 5 or higher degrade the ADSL signal? I ask as I don't know and basically because it's different to what I've seen in my own install.

I have Cat 5e to an extension junction box and then a number of extensions wired off that in Cat 5e - all see the same ADSL speed as having the router plugged into the master socket (~18Mbs so not, it's ADSL Max).

The only thing I've done in my set-up is to disconnect the ring wire from the extensions due to interference but that's pretty standard and essentially what the BT filter plate does.

 

[bernardgreen]

At the frequencies used in ADSL the characteristic impedance of Cat 5 cable at ADSL frequency is different from the characteristic impedance of telephone cable. Where the two types of cable join there is an impedance mis-match which causes some of the signal to be reflected back the way it came.

 

[ironsidebod]

At the frequencies used in ADSL the characteristic impedance of Cat 5 cable at ADSL frequency is different from the characteristic impedance of telephone cable. Where the two types of cable join there is an impedance mis-match which causes some of the signal to be reflected back the way it came.

Thanks, wondered what the science was. So, is mine working ok because I've used cat5 right from the extension connection in the master socket?

I probably should add that the error count is lower and the noise/attentuation figures are more favourable since I moved the router to the Cat5 run.

 

[CharlieB1981]

the router will be into the main socket with a filter on, thats planned already.

but are there any benefits to using cat5e/6 cable for telephone? or should i just used standard phone cable to save future issues?

also any views on if i'm allowed to replace the cable from the front of the house to the master socket or do BT have to do this, i phoned them and they said theyd need to visit to inspect, but i would be charged a call out fee if it wasnt their fault.

 

[ironsidebod]

I did a bit of reading after posting last night. No benefit to using cat anything for pure phone but the consensus is that using Cat5/6 for ADSL will improve the signal/noise ratio which is what I've seen.

If you think you might move the router in the future then you might want to consider using your Cat. cable.

The cable from the street to the back of the master socket belongs to BT so you shouldn't touch it.

 

[SimonH2]

There's an argument for using Cat5e or 6, simply on the basis that you can use the data cable for phone, but not the other way round. So running two data cables will allow for phone plus data, or 2x data, or data plus <something else> (perhaps HDMI over Cat5).

For myself, I'd use all data cable and data sockets - with adapters where I want to plug a phone in. But I can see that wouldn't suit everyone.

 

[trowelhead]

At the frequencies used in ADSL the characteristic impedance of Cat 5 cable at ADSL frequency is different from the characteristic impedance of telephone cable. Where the two types of cable join there is an impedance mis-match which causes some of the signal to be reflected back the way it came.

I am sorry, but that is absolute bull5h1t.
What about the differing types/ages of the BT network.
0.32,0.4,0.5,0.7,0.9 and even 1.17mm cable,either copper or aluminium.
Using cat5 or cat6 cable will not make your broadband slower or affect the service in any way whatsoever.
BT/Openreach actually supply cat5 cable for the infinity service.

 

[bernardgreen]

As you say there are many variants of the street cables between exchanges and the subscriber's property. When these cables were first installed there was no intention to use them for any purpose other then DC signalling and speech below 3 kHz ( 4 kHz in some countries ). The effective impedance of these vary considerably between types To put ADSL signals along these cable requires adaptive drivers and receivers at the exchange which adapt to the charactoristics of the cable they are driving.

CAT 5 has a nominal effective impedance of 100 ohms. If the incoming telephone cable has an effective impedance of 100 ohms then transisition losses and reflections are minimal. However where the incoming cable is not 100 ohms then the transisition losses and reflections can be significant.

At ADSL frequencies transmission line effects of the cable's construction have a significant effect.

The effect is most noticable at the end of long exchange lines.

A house 3 miles ( cable route ) from the exchange was internally wired with CAT5 from BT NTE 5 with filter plate ( as it was the best cable ) and broadband was slow. Replacing the CAT 5 from NTE 5 to router with CW1308 produced a noticable improvement in broadband download speeds.

 

[CharlieB1981]

thanks for the comments everyone.

bernardgreen- is there any way to check the impedence of the incoming BT line? or is it just safer to use CW1308 in the first place.

seems to be a very mixed view as to which may be better.

 

[trowelhead]

As you say there are many variants of the street cables between exchanges and the subscriber's property. When these cables were first installed there was no intention to use them for any purpose other then DC signalling and speech below 3 kHz ( 4 kHz in some countries ). The effective impedance of these vary considerably between types To put ADSL signals along these cable requires adaptive drivers and receivers at the exchange which adapt to the charactoristics of the cable they are driving.

CAT 5 has a nominal effective impedance of 100 ohms. If the incoming telephone cable has an effective impedance of 100 ohms then transisition losses and reflections are minimal. However where the incoming cable is not 100 ohms then the transisition losses and reflections can be significant.

At ADSL frequencies transmission line effects of the cable's construction have a significant effect.

The effect is most noticable at the end of long exchange lines.

A house 3 miles ( cable route ) from the exchange was internally wired with CAT5 from BT NTE 5 with filter plate ( as it was the best cable ) and broadband was slow. Replacing the CAT 5 from NTE 5 to router with CW1308 produced a noticable improvement in broadband download speeds.

Then please tell me why BT supply cat5 cable for their infinity broadband and not cw1308?

 

[bernardgreen]

is there any way to check the impedence of the incoming BT line? or is it just safer to use CW1308 in the first place.

There is a way to measure it, an expensive piece of test equipment will do it automatically or it can be done manually using several items ot test equipment.

or is it just safer to use CW1308 in the first place.

practical experience does suggest that CW1308 does give better results at the end of long exchange lines.

 

[bernardgreen]

Then please tell me why BT supply cat5 cable for their infinity broadband and not cw1308?

One Openreach engineer told me it is because the RJxx plugs cannot be crimped onto CW1308 cable so for ease of installation a cable onto which the plugs can be crimped is used.