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Standard User The_Voyager
(committed) Fri 10-Jan-14 19:12:08
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Re: Who is responsible?


[re: eckiedoo] [link to this post]
 
Exactly, I used to be an Observation Supervisor in exchanges after I was promoted from an International Operator, and some of the exchanges I went to were local ones, like Colombo Street, SE1, which also had a Crown above one of the boards.

In reply to a post by eckiedoo:
In the Exchange, such a call was identified by a flashing red light, if I remember correctly.


Bob WRBRIX
PN Unl.Fibre - Fritz! 7390 ~ Sync 79.99/20 Mb/s Avg 74.54/18.62 Mb/s @ 320m
DialUp to CIX, BT Home Highway to CIX, ADSL to Nildram, SKY & Be*Unlimited, Fibre to BT http://www.thinkbroadband.com/ping/share/049baa48c1f...
Standard User eckiedoo
(committed) Fri 10-Jan-14 19:35:06
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Re: Who is responsible?


[re: The_Voyager] [link to this post]
 
Thanks for that confirmation.

Also I seem to remember that the ideal, given those parameters, would have been "000"; but as a single "0" was already in use to "call the Exchange", any combination starting with "0"was excluded, leaving "999" as the working choice.

I suspect that it is why the USA "911" was arrived at for similar considerations, the leading "9" again to avoid the normal Operator call; and the trailing "11" to apparently speed up the process, due to the shorter rotations.

BUT that meant trying to find a second, different digit hole in possibly stressed situations, so removing any apparent technical advantage.

And the use of three digits generally to reduce the incidence of false calls.
Standard User WWWombat
(fountain of knowledge) Fri 10-Jan-14 21:45:28
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Re: Who is responsible?


[re: eckiedoo] [link to this post]
 
In reply to a post by eckiedoo:
Also I seem to remember that the ideal, given those parameters, would have been "000"; but as a single "0" was already in use to "call the Exchange", any combination starting with "0"was excluded, leaving "999" as the working choice.

[...]

And the use of three digits generally to reduce the incidence of false calls.

My understanding was slightly different, but it dates back to a bit of my training from the 80's, which I've never since used, so the information could be wrong, as could my recollection...

One need was a desire for the number to work from whatever location/exchange it was dialled from. A second need was for it to be free, especially from public phone boxes.

The choice of the first digit being 9 was then made because it was already used in small outlying exchanges to route local calls back to a main exchange, and could be made free from a call box.

So, for a call from an outlying exchange, local routing of the first '9' takes the call to a larger exchange, the 2nd and 3rd digits (whatever they would be) caused the call to be routed to the emergency operator (with the flashing red light).

Meanwhile, any call placed on the large exchange only needed to dial the 2nd and 3rd digits. If you wanted to publicise a single emergency number on every main & rural exchange around the country, the 2nd digit would have to be the same as the 1st (local routing) digit (i.e. a 9), and then the 3rd digit would also have to match the 2nd (i.e. a 9 too).

So, anyone connected to a main exchange strictly only needed to dial 99; the third was superfluous and ignored.

Clear as mud?

(The same training taught me that it was possible to get a cheap national call, so long as you knew each individual local ('9'-prefix) routing code to hop from exchange to exchange until you reached the final hop. Possibly a myth, I never tried it)


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Standard User MCM
(fountain of knowledge) Fri 10-Jan-14 22:08:39
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Re: Who is responsible?


[re: WWWombat] [link to this post]
 
(The same training taught me that it was possible to get a cheap national call, so long as you knew each individual local ('9'-prefix) routing code to hop from exchange to exchange until you reached the final hop. Possibly a myth, I never tried it)
No, not a myth. This was one of a number of methods that I was using as a uni student back in the mid 60's. There was another method, the details of which I have long forgotten, that used "private" pre STD trunk codes. In compiling our list of trunk codes we used to ring various combinations of numbers always ending in 1212 as this invariable ended in a Police Station where the person answering could be relied on telling us where they were, or rather the name of the police station. This avoided us having to say anything before hanging up and logging the newly established code.
Standard User cheshire_man
(knowledge is power) Fri 10-Jan-14 22:12:51
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Re: Who is responsible?


[re: johnjburness] [link to this post]
 
That, I was once told, is known as a borrowed neutral, and is (or was) against the regulations.

It was a common trick as it saved cable, but it had the effect to creating some interconnection between the downstairs lighting ring and the upstairs lighting ring.

Tony
We have more and more laws, and less and less enforcement
Standard User MHC
(sensei) Fri 10-Jan-14 22:24:27
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Re: Who is responsible?


[re: cheshire_man] [link to this post]
 
In reply to a post by cheshire_man:
That, I was once told, is known as a borrowed neutral, and is (or was) against the regulations.

It was a common trick as it saved cable, but it had the effect to creating some interconnection between the downstairs lighting ring and the upstairs lighting ring.


Basically yes, an installation with a "borrowed neutral" is likely to fail testing and could cause inadvertent/nuisance/false tripping or failure to trip of RCDs/RCBOs.

There are situations where it is legitimate but they are few and will be documented.


~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

M H C


taurus excreta cerebrum vincit
Standard User MHC
(sensei) Fri 10-Jan-14 22:26:04
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Re: Who is responsible?


[re: WWWombat] [link to this post]
 
In reply to a post by WWWombat:
(The same training taught me that it was possible to get a cheap national call, so long as you knew each individual local ('9'-prefix) routing code to hop from exchange to exchange until you reached the final hop. Possibly a myth, I never tried it)


Myth ... although there were a couple of places and routes it would work on.


~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

M H C


taurus excreta cerebrum vincit
Standard User johnjburness
(eat-sleep-adslguide) Fri 10-Jan-14 22:34:34
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Re: Who is responsible?


[re: MHC] [link to this post]
 
In reply to a post by MHC:
In reply to a post by cheshire_man:
That, I was once told, is known as a borrowed neutral, and is (or was) against the regulations.

It was a common trick as it saved cable, but it had the effect to creating some interconnection between the downstairs lighting ring and the upstairs lighting ring.


Basically yes, an installation with a "borrowed neutral" is likely to fail testing and could cause inadvertent/nuisance/false tripping or failure to trip of RCDs/RCBOs.

There are situations where it is legitimate but they are few and will be documented.

Without checking back through the Regs, I strongly suspect that it was Legit at the time my House was built (mid-70s), but I certainly don't believe that its permitted now - even if only for the potential reason of adversely affecting RCDs/RCBOs.

Regards,
John
Standard User KelvinBridge
(learned) Fri 10-Jan-14 23:58:34
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Re: Who is responsible?


[re: BatBoy] [link to this post]
 
In reply to a post by BatBoy:
I always phone up the Electricity company and have them disconnect my town from the National Grid before letting the wife change a light-bulb.



.......and I'll bet you warmed the water in the basin she was standing in !
Standard User The_Voyager
(committed) Sat 11-Jan-14 10:31:09
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Re: Who is responsible?


[re: WWWombat] [link to this post]
 
I think you are right, I seem to remember this as well, not from training, but from my school days, back in the 60s smile

I also remember from my BR days that there was a way to make calls on the BR system to European Railway Admins, I have quite a few railway friends in different countries , although some of the countries you had to go through the Paris operator, so needed to be able to speak a little French.

Another thing that was not well known, before IDD came in International Operators could direct dial using a keypad (omitting the zero on what is now IDD numbers) except to countries where there were manual or radio circuits (e.g: Saudi Arabia, Ghana)

In reply to a post by WWWombat:
(The same training taught me that it was possible to get a cheap national call, so long as you knew each individual local ('9'-prefix) routing code to hop from exchange to exchange until you reached the final hop. Possibly a myth, I never tried it)


Bob WRBRIX
PN Unl.Fibre - Fritz! 7390 ~ Sync 79.99/20 Mb/s Avg 74.54/18.62 Mb/s @ 320m
DialUp to CIX, BT Home Highway to CIX, ADSL to Nildram, SKY & Be*Unlimited, Fibre to BT http://www.thinkbroadband.com/ping/share/049baa48c1f...
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