*Five* wire overhead mains cables

And my reply. They are there to make 4 wires stay as 4 wires.

If so, then using kevlar would ensure that there was nothing conductive.

No, but I thought of that as I was watching Netflix. I also found out if I hold the line the buzzing increases !!! Maybe I am acting as an aerial.

OK - are you going to try swapping? Is that you holding the 'phone or the power cable? It'd be interesting to see a sketch of the network of phones - showing any broadband filters. Is each extension used for phone only, broadband only, or both? Does any of the network still include a third, "bell" wire?

PA

Conductor temperature has other significance. They can (and do) carry more current in the winter than the summer while staying within the "sag" allowance from thermal expansion. A rare example of Sod getting it wrong.

You could be right although I suspect that each supergrid voltage has its own optimised cable. I'm pretty sure the individual insulator elements in 275kV and 400kV are different (as well as the stringers being longer for 400).

L1, L2, L3, Street Lighting, N

Yes, drop wires that they've already installed contain a copper pair, but will they continue with that now they're going fibre-only and using voip? I'd have thought they'd want to remove all temptation for the thieves.

I have seen two different types of drop cable being installed recently. One has a copper pair alongside the fibre cable. The main strength element appears to be kevlar or something similar. The other drop cable has nothing metallic. My sister in law has the type with a copper pair and was recently told by BT that she would be moved to VoIP and the copper service discontinued. This is a rural location with long unreliable copper lines.

I don't know how the multi-fibre cables used for long overhead runs are strengthened, but whatever it is works well at holding up fallen trees.

John

That is a straw man. times 4 conductors increase powwer capacity *at the same voltage*

Its a neat way to up the power without having to increase voltages which would probably in the end cost more

i expect they will in time drop them, yes

our 'copper' exchange is due to be closed in 2016.

I wish I could be living in the past like you

yes should be 2026

I'll try the swapping tonight. The phone has a headset and I was holding the cable to the headset.

Master socket (filtered) > ext 1 > ext 2. I had to reconnect the bell wire as ext 2 does not ring without it. The only broadband filter is contained in the master socket. The route from ext 1 to ext 2 runs under the floor close to a ring main and my TV set, which I assume is the source of the problem.

Just a couple of observations.

How many phones of the last 25 years need bell wires?

You don't get any significant radiation at "hum" frequencies from TVs - unless they are similarly ancient Cathode-Ray-Tube ones?

I take it you hear this hum when you've made the call as well as when you've answered them on the humming ext? Try the ext1 - ext2 handset swap. Then swap back and try disconnecting the bell wire - everywhere you can - and then make a call using the hummer - or call yourself from a mobile and pick-up on the hummer handset, see if the hum is gone.

By the way, what actually is ext2? is it a mains (or anything else)

-connected thing e.g. a fax machine?

PA

No, it would be cheaper to do that with one fat wire, which would need slightly more conductor to reduce the heating effect. THE REASON FOR FOUR SPACED CONDUCTORS WAS TO REDUCE CORONA LOSSES AT 400kV.

On Wed, 21 Apr 2021 19:06:42 +0100, Peter Able snipped-for-privacy@home.com wrote: [snip]

Probably very few but I think this one does. It stopped ringing then I found the bell wire had come loose. Now it rings again. It is a Cable & Wireless CWB 200H.

It's in the kitchen so not a problem. I thought proximity to a ring main was a problem due to inductive effects like a transformer.

Yes, incoming and outgoing. I swapped the handsets and the C&W worked okay at point ext 1. The other phone (BT Relate 250) worked okay at point ext 2. Given these circumstances, the bell wire does not seem to be the problem.

Not mains. The only distinctive feature is the headset. I have tried again and if I grip the cable to the headset the buzzing gets much worse. Even at point ext 1, gripping the headset cable creates humming.

I could buy a replacement headset phone but they seem to be few and far between and none of them seem to get good reviews.

Are we not getting VOIP by 2025 anyway?

So the problem appears to be the phone not the extension cabling. Now you say the effect is related to your closeness to the headset cable. That reinforces that conclusion. I can find nothing on Google about the C&W phone - except a site for the 100H - which AVG reckons is infected.

If the C&W can be operated without the headset - try it.

Looking increasingly like a bin job; just what to bin - the headset or the lot.

PA

I tried that too, and another site. One was infected and one took me to a gambling site.

Done that. It's fine using the handset. To my mind the cable to the headset is acting as an aerial. It gets much worse if you grip the cable. Maybe I am acting as an aerial too.

I had to replace the headset about a year ago. I think the previous one did the same. Could this be a characteristic of all headsets? I could replace the phone but none of the present generation seems to review well. According to R4 this morning, landlines are a thing of the past anyway!