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Old 31st Dec 2017, 2:09 pm   #21
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Default Re: Earthing of phone lines

The earth wire went to a copper earth spike hammered into the ground.

In the telephone area where I worked in the late 1960's all new residential lines were provided with an earth so that they could easily be converted to shared service should this be necessary at a later date.
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Old 31st Dec 2017, 2:21 pm   #22
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Default Re: Earthing of phone lines

The wiring for external extensions on a Planphone (Plan 105 or 107 with external extensions), see diagram N4507 or N4509 depends on an earth at the 'main' telephone and at the extension.

That is shown in the diagram.

What is not obvious (unless, like me you have battled through the circuits) is that it also depends on the 'a' wire being essentially earthed at the exchange.
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Old 31st Dec 2017, 2:23 pm   #23
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Default Re: Earthing of phone lines

Earth 'A', Battery 'B'.
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Old 31st Dec 2017, 3:21 pm   #24
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Default Re: Earthing of phone lines

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Originally Posted by Station X View Post
In the telephone area where I worked in the late 1960's all new residential lines were provided with an earth so that they could easily be converted to shared service should this be necessary at a later date.
Were they still fitting lightning arrestors then, Graham, or was the earth tied up in a junction box out of use?
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Old 31st Dec 2017, 3:36 pm   #25
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Default Re: Earthing of phone lines

By that time the use of open wire "drops" to the customer's premises had ceased and "drop wire" (twin steel copper coated wire in a figure of eight sheath) was being used.

Lightning protection was only considered necessary on lines with more than 4 spans of overhead wire and was fitted at the pole top.

The earth wire was terminated on a terminal block in the customers premises, generally close to the point of entry. This wasn't necessarily the terminal block which came with the phone, and cable would be used between the two blocks.
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Old 31st Dec 2017, 4:41 pm   #26
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My solution was to supply back with mains connected to the phone line
I regard that as a trifle dangerous for some poor chap at the other end (unlikely but possible), please don't do it again.
 
Old 31st Dec 2017, 5:54 pm   #27
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Default Re: Earthing of phone lines

I thought it was always taught as good practice to check for unexpected high voltages on the line before commencing work. I dare say in this instance it could have saved some unsuspecting engineer's life. I must say I don't always do it but we tend to work on "private" networks where we have a little more control over what people get up to. Regarding earthing, we still have some legacy cream coloured functional earth wires here and there, for things like call forwarding from extensions. Some of our switches are quite old though. Probably not that common on modern BT systems.
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Old 31st Dec 2017, 6:15 pm   #28
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Default Re: Earthing of phone lines

the eth wire was also used for the "recall" button fitted on some remote extensions, the eth recall has been replaced by "timed break recall" on modern systems.
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Old 31st Dec 2017, 6:23 pm   #29
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Default Re: Earthing of phone lines

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The earth wire was terminated on a terminal block in the customers premises, generally close to the point of entry. This wasn't necessarily the terminal block which came with the phone, and cable would be used between the two blocks.
Thanks for that, Graham. Thinking back, that was the arrangement at my grandma's house when she got her telephone installed in 1971. But she had a party line. The earth block was just behind the front door not far from where the dropwire entered.

We got our telephone installed a year earlier but there was no earth connection. Perhaps party lines were on the way out by then?
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Old 31st Dec 2017, 9:19 pm   #30
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I heard a story that in the hot summer of 1976, a couple found that their phone was playing up. Sometimes it just refused to ring at all. The times it did ring, their dog would always bark before the telephone rang. And their dog had developed a sudden, strange aversion to going outside .....

How was all this connected?

They were on a party line, so the ringing voltage was applied between one leg of the line and Earth. Due to the dry conditions, the Earth connection at the base of the pole near the house was reading an abnormally high resistance; so there was a significant potential difference across the ground near the pole when the phone rang. When they were all sitting outside, the dog's lead was often tied to the telephone pole -- and that meant there was a significant potential difference between the dog's backside and its front paws ..... The poor animal had been getting electric shocks from the ringing voltage, losing control of its bladder, and in the process, improving the Earth continuity enough to make the phone ring!
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Old 1st Jan 2018, 10:53 am   #31
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Default Re: Earthing of phone lines

About 15 years ago I built a pole barn to house my old lorries. The poles came from a very small local village and are dated 1947/49.

They each have an earth wire stapled along their length that terminates to earth via a spiral coil on the ground end of the pole. I would add that the six poles are in perfect condition with everything in place.

I certainly remember the telephone earth wire from houses that were probably connected pre war. John.
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Old 1st Jan 2018, 2:18 pm   #32
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Default Re: Earthing of phone lines

I clearly recall the (non-party line) phone installed in the living room of my parents' house. Installed around 1939, it was permanently wired via its local junction box on the windowsill into a larger black bakelite junction/protection box at the top of the window frame which ISTR incorporated some form of spark gap surge arrestor. It had a stranded bare copper earth wire connected to an earth rod just outside the house.

Local phone wiring was carried down the road on poles rather than underground: I recall the many overhead pairs of wires visible from my bedroom window. An open wire connection from the nearest pole was anchored to a twin ceramic insulator at the front of the house. GPO wiring then ran round the gutter board to the back of the house where it dropped down and was fed through the living room window frame to enter the protection box along with the earth wire and then to the black bakelite phone on the windowsill.

The attached pictures illustrate my memories of the installation.
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Old 2nd Jan 2018, 9:36 am   #33
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Default Re: Earthing of phone lines

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It would be interesting if your method of getting the company's attention/ cooperation was in more general use dsk: Boaters Sam's description of the earthing set up [post 10*] matches the redundant wiring I found in the front garden here in Bexhill. I'd always known that earth wires might be deployed in telephone installations from my employemt [as a clerk] in the GPO circa 1968 but I was intrigued to read the technical background here.
I used a local ground, mainly connected to the water pipe, this is also connected to the electric panels in the house.
Grounding for telephones has been used for different needs during the years: Grounding for protection by having to high voltage lead to earth/ground via a spark gap or other devices. For real old systems or party-lines they may have used the ground for ringing or billing systems, but probably not installed new the last 50 years, and probably not used for the last 30. In some PABX systems ground was used for a recall button for e.g. transferring to another phone.

How could a ground problem come in our house? A nail, or a clomp or something else hits the wire, and something with current carrying capacity to ground. In the 50ies they used some flat cable here, just nailed in the middle to the wall, if you touched one strand, and the nail hit a wet surface it could cause a temporarily fault, until it dried up.

What to do? Go to the inlet in the house ( or close to) disconnect the phone-wires to the house, and connect a phone jack (master socket) and try from there. If everything is OK, the fault is in your house. You have to locate that one.

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Old 19th Jan 2018, 11:37 pm   #34
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Default Re: Earthing of phone lines

Quote:
Originally Posted by julie_m View Post
I heard a story that in the hot summer of 1976, a couple found that their phone was playing up. Sometimes it just refused to ring at all. The times it did ring, their dog would always bark before the telephone rang. And their dog had developed a sudden, strange aversion to going outside .....

How was all this connected?

They were on a party line, so the ringing voltage was applied between one leg of the line and Earth. Due to the dry conditions, the Earth connection at the base of the pole near the house was reading an abnormally high resistance; so there was a significant potential difference across the ground near the pole when the phone rang. When they were all sitting outside, the dog's lead was often tied to the telephone pole -- and that meant there was a significant potential difference between the dog's backside and its front paws ..... The poor animal had been getting electric shocks from the ringing voltage, losing control of its bladder, and in the process, improving the Earth continuity enough to make the phone ring!
jules- I spent a lot of my Telecomms time in a part of Scotland, where earth leakage and bad earths was a problem. At one site, we installed a planset, where ringing depended on a good earth( 105/7?) and ended up burrying an old car radiator, with an earth spike through it. At home, we had a substation at the end of the garden, and ghost ringing on shared service was a problem. At one stage, I measured 150V AC across our garden gate. in the village, we had dogs sniffing drainpipes and getting shocks. Quite funny as other dogs came to investigate and as soon as leg was lifted and pee hit pipe, dog got shock and moved off, to be followed by another.
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Old 26th Jan 2018, 1:45 am   #35
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Default Re: Earthing of phone lines

Regarding post #6, Decades ago, some telephone lines in the USA and presumably elsewhere DID consist of a single wire and an earth return.
The existence of such systems was a barrier to early rural electrification projects, since it was considered that the new fangled electric light would interfere with the existing telephone.

Some private telephone systems on large estates used a single wire and the lighting system neutral or return as the other conductor.

In some cases the telephone company expected the power company to pay for "metalicising" the phone lines, i.e. providing a second insulated wire in place of the earth return.
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Old 26th Jan 2018, 10:20 am   #36
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Decades ago, some telephone lines in the USA and presumably elsewhere DID consist of a single wire and an earth return.
I'd always been curious as to why some properties back in the day, both rural and urban, only had one single insulator, whereas others in the immediate vicinity had the usual two No: 16 'pot-heads' (like my avatar) on a 'J'-bracket. I may have mentioned it on this forum before.

Evidently - from info gleaned over at the THG - they were for Firemens' and Lifeboatmens' call-out alarms and used a single wire earth return to sound a bell at the property.
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Old 26th Jan 2018, 12:27 pm   #37
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Also from telegraph circuits to local post offices in days of old. The attached photo is of the junction linking Diabaig exchange to Torridon exchange some ten miles away. To my knowledge Diabaig was the last exchange connected to the rest of the network by a bare copper pole route until March 1995 when it was replaced by 3 microwave links. On top of each pole was a single spindle, some with insulators still on. Diabaig didn't get a road to it until the 1960's but this pole route goes way back to the 1800's. The poles had no markings on them rather than the markings usually found denoting the length diameter and date. When the telegraph companies were nationalised under 1869 Telegraphs Act, it was soon followed by the GPO extending the network to remote post offices. A lot of this was undertaken by the Royal Engineers in remote areas of Scotland. Diabaig didn't get the telephone until 1937 when a small magneto exchange on the post office with two lines off it went into service. It survived with its two lines until it was closed down circa late 1958. It was reopened in the early 1980's with a UXE7 (miniature version of a TXE2). The UXE7 was a couple of miles outside the village and the old pole route had an aerial cable run along it with the pole still having their single insulator on to but no signs of ever having arms fitted! All now gone or replaced with newer poles.

I remember when I was with God's Poor Orphans - going on a fault with the lineman to a fault in the Tarporley exchange area - then a new UAX13. Also they had recently had a new fireman's call our system based on a teleprinter in the unmanned 'retained' firestations of which Tarporley was one. The bells were triggered by the teleprinter once the details were printed out from Control. Problem was the system kept ringing the bells but no message! Eventually it was traced to a poor earth at one of the fireman's houses which was shared with the shared service earth. Problem was that the 50 volts from the telephone line via the Call Exchange button was going to earth via all the other firemans' call bells rather than directly to earth. Once found the number of 'callouts' dropped considerably!
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Old 30th Jan 2018, 12:02 am   #38
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Default Re: Earthing of phone lines

P-as I mentioned previously- one constant problem on the west coast was bad /poor mains earthing. To a trained ear, bell tinkle from mains leakage was very different to 17/20 ringing. Exchange ringing to Shared service/plansets/call out bells went via OH, through bell to earth. False tinkle, went in the reverse direction.
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Old 30th Jan 2018, 2:39 pm   #39
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Quote:
Originally Posted by Biggles View Post
I thought it was always taught as good practice to check for unexpected high voltages on the line before commencing work. I dare say in this instance it could have saved some unsuspecting engineer's life. I must say I don't always do it but we tend to work on "private" networks where we have a little more control over what people get up to. Regarding earthing, we still have some legacy cream coloured functional earth wires here and there, for things like call forwarding from extensions. Some of our switches are quite old though. Probably not that common on modern BT systems.
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Prudent, and especially important on railway telephone, telegraph, and signalling circuits.
Decades ago, the railway used to send mains voltage along telegraph routes as a cheap way of supplying mains to signal boxes etc.
The insulators used thus were meant to be red in colour instead of off white, and on multi circuit routes were so placed so as to minimise the chances of accidental contact.
The capacity of such a circuit was very limited indeed, but still useful for basic lighting and for battery charging. Heating and cooking would be by coal of course which was available everywhere on a steam powered railway.
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Old 30th Jan 2018, 4:07 pm   #40
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Default Re: Earthing of phone lines

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Decades ago, the railway used to send mains voltage along telegraph routes as a cheap way of supplying mains to signal boxes etc.
The insulators used thus were meant to be red in colour instead of off white, and on multi circuit routes were so placed so as to minimise the chances of accidental contact.
I have one of those red insulators (ex-Settle and Carlisle rly). They were mounted on the furthest end of the top crossbar, and yes: they would support mains conductors as you describe.

But were they on an earth return system too? Or would there be live and return (possibly floating) conductors along the same run as telegraph ccts?
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Last edited by russell_w_b; 30th Jan 2018 at 4:35 pm. Reason: Elaboration.
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