IET logo
 
IET
Decrease font size
Increase font size
Topic Title: Mixing Bands
Topic Summary:
Created On: 17 December 2012 09:11 PM
Status: Post and Reply
Linear : Threading : Single : Branch
Search Topic Search Topic
Topic Tools Topic Tools
View similar topics View similar topics
View topic in raw text format. Print this topic.
 17 December 2012 09:11 PM
User is offline View Users Profile Print this message


Avatar for MrOther.
MrOther

Posts: 530
Joined: 08 June 2010

I know nout about tele-communications as a general rule, so any addition insight is a bonus.

I have an old Telephone socket, plastic clad and surface mounted. Intend to convert to a nice new flush fitting. Cable to put into wall horizontally a long safe zone. Next to it I'm gonna intsall a new socket. Metal clad. Hoping to get an all in one.

If memories serves when mixing Band I & II new Regs stipulate this is okay as long as the cables can withstand the highest nominal voltage, i.e. the telephone cable will have to withstand 230v -- which I think is a nonstarter.

If this is the case, if I serperate the pair into seperate back boxes with a metal interconnecting clip - just to make it easier to mount and to make sure they are parallel, would this still be a problem? Only under fault conditions methings.

Thanks again.
 17 December 2012 10:19 PM
User is offline View Users Profile Print this message


Avatar for Legh.
Legh

Posts: 3472
Joined: 17 December 2004

I wouldn't want to mix Sparks with ACDC somehow

On the other hand you could bury a plastic backing box in the wall and keep them completely separate...
But then you'd have your work cut out making it look respectable.

Legh

-------------------------
Why do we need Vernier Calipers when we have container ships?

http://www.leghrichardson.co.uk

"Science has overcome time and space. Well, Harvey has overcome not only time and space - but any objections."
 18 December 2012 06:46 AM
User is offline View Users Profile Print this message



normcall

Posts: 8111
Joined: 15 January 2005

Start with worrying about all the hum and noise that might be introduced and you should be on the right track.
In my conservatory, I wanted a socket, a telephone point and network outlet.
Two single boxes mounted as you suggest, with one of those 'link clips' to get them spaced correctly.
power to socket and I used a combined telephone and network outlet (you could use a 2 unit grid , one for telephone and other for network).
Seems to work OK without any noise.

-------------------------
Norman
 18 December 2012 07:40 PM
User is offline View Users Profile Print this message


Avatar for MrOther.
MrOther

Posts: 530
Joined: 08 June 2010

Originally posted by: normcall

Start with worrying about all the hum and noise that might be introduced and you should be on the right track.

In my conservatory, I wanted a socket, a telephone point and network outlet.

Two single boxes mounted as you suggest, with one of those 'link clips' to get them spaced correctly.

power to socket and I used a combined telephone and network outlet (you could use a 2 unit grid , one for telephone and other for network).

Seems to work OK without any noise.


Norm I am just reusing the cable that is there -- little white multi-core thing.

As you described, the telepone is in a seperate backbox to the power but obviously are linked by cpc on the metal back box link. Is there any issues with this re: regs.

As I said, my concern is under fault conditions the telephone cable will not be suitable under fault conditions.

Sorry, if this seems pedantic, but I don't want to do my Ma's room up and muck about without offering her better then what she had.

She does the cooking, after all.
 18 December 2012 08:00 PM
User is offline View Users Profile Print this message


Avatar for MrOther.
MrOther

Posts: 530
Joined: 08 June 2010

Similarily I'm also installing a socket and plug with a back box clipping them together.

EDIT: Reg 528.1 doesn't seem to address my concerns but I guess if it allows for both Bands to be on the same metal tray physically seperated then it should be okay because one would presume that the tray would be earthed.

Edited: 18 December 2012 at 08:30 PM by MrOther
 18 December 2012 10:14 PM
User is offline View Users Profile Print this message


Avatar for Legh.
Legh

Posts: 3472
Joined: 17 December 2004

I think the BT lines are FELV so at some point there is a common earthing point. (50V dropping to 38V when the line goes hot)

I can't speak for the BT insulation though. It doesn't look that resistant.

Legh

-------------------------
Why do we need Vernier Calipers when we have container ships?

http://www.leghrichardson.co.uk

"Science has overcome time and space. Well, Harvey has overcome not only time and space - but any objections."
 19 December 2012 07:34 PM
User is offline View Users Profile Print this message


Avatar for MrOther.
MrOther

Posts: 530
Joined: 08 June 2010

That's Legh.

I think for the sake of "noise" I'll keep the Ariel and Telephone cabels away from mains.

One more question:how can you tell if a telephone socket is a seondary or master?
 19 December 2012 07:40 PM
User is offline View Users Profile Print this message


Avatar for Legh.
Legh

Posts: 3472
Joined: 17 December 2004

The master will have a resistor and capacitor connected across the lines (filtering)
Secondary outlets are just paralleled up.

Legh

-------------------------
Why do we need Vernier Calipers when we have container ships?

http://www.leghrichardson.co.uk

"Science has overcome time and space. Well, Harvey has overcome not only time and space - but any objections."
 20 December 2012 12:32 AM
User is offline View Users Profile Print this message


Avatar for MrOther.
MrOther

Posts: 530
Joined: 08 June 2010

Originally posted by: Legh

The master will have a resistor and capacitor connected across the lines (filtering)

Secondary outlets are just paralleled up.



Legh


Your a gentleman, thanks.
 20 December 2012 10:48 AM
User is offline View Users Profile Print this message



AJJewsbury

Posts: 11299
Joined: 13 August 2003

The master will have a resistor and capacitor connected across the lines (filtering)

The capacitor is actually to generate the ringing signal (blocks d.c.) rather than as a noise filter and the resistor is there so that the exchange can tell the difference between nothing being plugged in and the line being broken (out of service resistor).

The reason the ringing capacitor is in the master socket, rather than in individual phones, dates back to the old rotary dials - which generated pulses. The pulses are of course a kind of brief a.c. so got through the ringing capacitor and causes the bells to "tinkle" when dialling out. To stop this the dials had a contact which shorted out the bells when the dial was anywhere other than its resting position. Once you could plug several phones into the same line, for the shorting out to be effective they had to share a single common ringing line (pin 3 I think) and so one capacitor.

- Andy.
Statistics

See Also:



FuseTalk Standard Edition v3.2 - © 1999-2014 FuseTalk Inc. All rights reserved.