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Vintage Telephony and Telecomms Vintage Telephones, Telephony and Telecomms Equipment |
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11th Jul 2020, 8:04 pm | #1 |
Hexode
Join Date: Jan 2012
Location: Weymouth, Dorset, UK.
Posts: 422
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BT street equipment cabinets
Can any one tell me if the green BT cabinets for conventional phone lines, the sort that have been around for years not the new digital ones, have any power supply's built into them? The reason I ask is because I saw inside the one at the top of my road the other day, and noticed some fairly thick looking green/yellow wiring connected to the metal doors and sides of the cabinet. That's why I'm asking.
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11th Jul 2020, 9:04 pm | #2 |
Heptode
Join Date: Apr 2008
Location: Eastbourne, East Sussex, UK.
Posts: 671
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Re: BT street equipment cabinets
If it's thick green/yellow wiring that would be earth bonding to keep all the parts of the cabinet at the same potential for safety.
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12th Jul 2020, 7:20 pm | #3 |
Dekatron
Join Date: May 2010
Location: Greater Manchester, UK.
Posts: 18,725
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Re: BT street equipment cabinets
Those who work on line-plant must be mindful that dangerous voltages could unexpectedly be introduced via faulty customer premises equipment.
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12th Jul 2020, 7:34 pm | #4 |
Moderator
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Re: BT street equipment cabinets
Also there is the possibility of high voltage surges induced by lightning in overhead sections of line. Normal ye olde worlde telephone cabinets just had -48v from the exchange battery via hundreds of ohms on each exchange line.
Phone equipment in the home/office used to be tightly controlled especially with respect to anything using mains. David
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12th Jul 2020, 11:30 pm | #5 |
Hexode
Join Date: Jan 2012
Location: Weymouth, Dorset, UK.
Posts: 422
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Re: BT street equipment cabinets
It makes sense now why they would need to have the cabinets properly earth bonded next time they are working in it il try to have a better look. Radio wrangler why is it -48 volts? Is this the 55 volts from the battery minus the volt drop of the wiring?
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13th Jul 2020, 6:50 am | #6 |
Hexode
Join Date: Apr 2006
Location: Medway towns, Kent, UK.
Posts: 271
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Re: BT street equipment cabinets
One of the first 'powered' cabinets came with the wifi installations for the 'open cities' project. I was the lead test manager for that and had to spec up the use of mains powered equipment. (including 24 hour noise tests). The other normal powered equipment is the fibre and DSLAM cabinets, which have to be close (spec was originally under 5m away) to the original cabinets which only carry normal phone voltages.
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13th Jul 2020, 11:09 am | #7 |
Hexode
Join Date: Jan 2012
Location: Weymouth, Dorset, UK.
Posts: 422
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Re: BT street equipment cabinets
Thanks bobster that really answers my original question thanks. So far all but one of the new fibre cabinets I've seen are only a very short distance from the original cabinets as you say within 5 yards/metres however a newly installed one just up the road from here is out on its own although it's linked back to one at the top of my road in fact before they started work someone had written the words PARENT POWER on the pavement just in front of it so I guess the new box is fed from this possibly to avoid having to pay yet another power connection charge
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13th Jul 2020, 1:27 pm | #8 |
Dekatron
Join Date: Apr 2012
Location: Wiltshire, UK.
Posts: 14,007
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Re: BT street equipment cabinets
One thing I've always wondered about the 'powered' street-cabinets is - how is the electricity they use charged-for? Is there a meter inside the box? Or is there some generally-accepted-power-consumption figure that's been neasured for an 'average' box and this is simply multiplied by the number-of-boxes?
I watched the installation of the nearest one to me [it's fed from the same underground 3-phase supply which then goes up onto overhead-wires to feed my house] but never got to see its insides. |
13th Jul 2020, 1:47 pm | #9 |
Pentode
Join Date: Jun 2020
Location: Bude, Cornwall, UK.
Posts: 183
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Re: BT street equipment cabinets
I think they charge for power the same way as they do for street lights, they don’t have individual meters either.
A fixed charge based on calculated usage of power, it would cost too much to fit individual meters. |
13th Jul 2020, 3:44 pm | #10 |
Dekatron
Join Date: Feb 2005
Location: West Cumbria (CA13), UK
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Re: BT street equipment cabinets
Not only that, but it would require a meter reader to go round and read them all - unless they were "smart" meters.
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13th Jul 2020, 9:02 pm | #11 |
Dekatron
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Location: Bradford on Avon, Wiltshire, UK.
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Re: BT street equipment cabinets
The nearby ADSL fibre DSLAM is mains powered and there are tie cables carrying customer’s lines in and out. There have been a few ( rare) instances of cabinet shells being live so they should all be bonded. Engineers are supposed to test for “ liveness” with one of those voltage detectors before starting work.
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14th Jul 2020, 6:58 am | #12 |
Hexode
Join Date: Apr 2006
Location: Medway towns, Kent, UK.
Posts: 271
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Re: BT street equipment cabinets
yes we are charged for power based on what the power consumption is. An earlier installation in Cardiff I worked on put mobile phone masts inside lamp posts and we had to notify which ones and how many to pay the council who paid the additional costs. Some of them have now been working in Cardiff for nearly 20 years. We were the first to combine both 2G and 3G and 4 operators all within one installation providing a mesh across the city.
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16th Jul 2020, 3:19 pm | #13 |
Dekatron
Join Date: Apr 2005
Location: North Wales, UK.
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Re: BT street equipment cabinets
The telephone kiosk opposite (now gone) had a small fluorescent light in it that was on permanently and fed by an unmetered supply from our house across the road.
We used to own and maintain a TV distribution system for a village and our supply was unmetered and based on an assumed constant usage. |
16th Jul 2020, 4:01 pm | #14 |
Heptode
Join Date: Oct 2006
Location: Leeds, West Yorkshire, UK.
Posts: 598
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Re: BT street equipment cabinets
I'm intrigued by the TV aspect, Glyn. Was your system anything like a small Rediffusion network ?
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