Quick and random geek question

Hi folks,

Need to run a telephone extension over about 10 metres of existing Cat5. Should work right, resistance ain't going to be too high across the cat5? Oh, and has anyone wired in a new backbox & socket? Guessing I only need worry about 2 pairs, also guessing it's just a straight-through pinout?

Cheers

EDIT: Should point out, it's a regular BT pstn line.

Resistance wont be a problem at all. all copper wire should match almost perfect same ohm rating.

You should really patch it from the PSTN line onto the Cat V properly and then use a CAT V outlet with the propper dongle to ensure it all works fine, but from what you are saying i assume you are cut and shut it?? i.e PSTN-CAT V - Telephone outlet??

yes a normal phone is on 2 wire working, so just check the working pairs the phone line is using and connect to the CAT 5. They normally are straight through in outs.

[SoulKiss]

Note that it is Illegal to take the front off of a BT Primary Socket.

[TSM]

Originally Posted by SoulKiss

Note that it is Illegal to take the front off of a BT Primary Socket.

Not anymore from what ive been told. What i was told is, that years ago that law was there to prevent damage to the exchange, but now there are protections in place to stop things happening so its not an issue any more.

In my old office i made the BT people install new lines to the internal DP box we had, then i ran several CAT5 cables to the patch in the cab, for each CAT5 i could run 4 seperate lines into the patch.

All fine and BT had no issues with me doing that, infact we did not even have BT Primary Sockets installed by BT.

Many phones nowerdays will still ring even if you dont have a Pri Socket. All that the Pri does is take the two wires and give an extra wire for the ringer, but phones realy dont need it any more as it does it internaly.

Pedant alert:

Originally Posted by neio79

yes a normal phone is on 2 wire working, so just check the working pairs the phone line is using and connect to the CAT 5. They normally are straight through in outs.

Extensions after the primary socket are 2 wires. Other than that, carry on.

Only question that I can't see is answered, yes, it's straight through for BT cabling.

Originally Posted by Baph

Pedant alert:



Extensions after the primary socket are 2 wires. Other than that, carry on.

Only question that I can't see is answered, yes, it's straight through for BT cabling.

I did say all that in a round about way!

Cat 5 is fine for phones. Since the system was designed to run on Cat1.

Also, dont try and strip the wire with your teeth once one end is connected. Theres some nice voltage going down there.

Oh, and buy a punch down tool! Dont try using screwdrivers.

Dan

[TSM]

Originally Posted by Baph

Pedant alert:



Extensions after the primary socket are 2 wires. Other than that, carry on.

Only question that I can't see is answered, yes, it's straight through for BT cabling.

The other way round, two wires to the back of the primary socket then three from the removable bit of the pri socket to all other secondary sockets. 3rd wire is the bell wire.

Thanks guys You know, if I'd have mentioned this on a cisco forum there would have been a 48 hour delay, followed by a long discussion about why I don't just use IPT and stick CCM in... Wheras, ask on an SV forum and you get the answer right away

All done, yep, was a cut and shut job on the cat5, didn't have any crimps for BT style plugs (608A?) but found an RJ45 to BT converter lying around, then wired in a new back box at the other end. No, I didn't have an IPC tool to punch down, so yes, had to use a screwdriver and The Special IT Tool (aka, a paper clip).

if some1 rings you while holding the wires it give you quite a shock