> On Tue 04 Mar 2008 21:22:30, ipal.net> wrote:
>

>> In alt.engineering.electrical gfretwell@aol.com wrote:
>> | On Tue, 4 Mar 2008 19:13:07 -0000, "Graham." privacy.com>
>> | wrote:
>>
>> |>It is quite difficult to induce hum into telephone wiring.
>> |>Use twisted pair cabling rather than the flat ready-made
>> |>extension cables.
>> |
>> | Exactly!
>> | The phone company has millions of miles of cable running right
>> | below power lines and hundreds literally touching each other in
>> | the jacket of the cable. That little twist they put in the pairs
>> | is excellent in isolating them from crosstalk.
>>
>> That twist is a great little means to ensure induced signals,
>> whatever they may be, are induced in equal amount on both wires, so
>> they do not contribute to the actual intended signal that is a ...

> On Tue 04 Mar 2008 19:13:07, Graham. privacy.com> wrote:

>> "Foxtrot" wrote in message
>> news:Xns9A57AA15ACE8ED712E3@127.0.0.1...

> In alt.engineering.electrical gfretwell@aol.com wrote:
> | On Tue, 4 Mar 2008 19:13:07 -0000, "Graham." privacy.com> wrote:
>
> |>It is quite difficult to induce hum into telephone wiring. Use twisted...

>I am in the UK and want to make several phone extensions.
>
> QUESTION: I would like to know I this will increase the level of hum.
>
> ISTR UK phones have a transformer and some other components to
> neutralise hum but would that be good enough to prevent hum from a messy
> setup like mine? Some details are below.
>
> -------------------------
>
> In my situation the phone extension wires and the mains wires will run
> close to one other.
>
> There will be about four or five additional extension phone sockets.

> I used to see phones rated in terms of their "ringer equivalence" here in
> the USA. These numbers were, for some phones, as low as 0.2. I do not
> recall ever seeing one about 0.9. That would suggest to me that you could
> readily have more than 4 phones on such a phone circuit. I never had any
> reason to actually do a scientific test of this.

>| One contribution I would make is that you are aware that your phone service
>| will support 4 REN and that each phone is normally 1 REN, meaning that you
>| can have a maximum of 4 phones. My parents had more of this and whilst from
>| their perspective it seemed to work (they could call out), it stopped people
>| from calling in because their phones stopped ringing.
>
>I used to see phones rated in terms of their "ringer equivalence" here in
>the USA. These numbers were, for some phones, as low as 0.2. I do not
>recall ever seeing one about 0.9. That would suggest to me that you could
>readily have more than 4 phones on such a phone circuit. I never had any
>reason to actually do a scientific test of this.
>

> "Foxtrot" wrote in message
> news:Xns9A57AA15ACE8ED712E3@127.0.0.1...

>> I am in the UK and want to make several phone extensions.
>>
>> QUESTION: I would like to know I this...