Ring or Radial
- Thread starter geome
- Start date
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In which case you know F-all about testing ring mains
At least I know enough to call them by their correct name.
i'm sorry, that was a deliberate error, never mind
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Sorry, I just realised it was you I'd responded to in the first place!i'm sorry, that was a deliberate error, never mind
D'oh!
Rings for me
Ring mains are single fault tolerant, keeps all the sockets working and avoids the following dangerous situation
Radial with four sockets. Socket furthest from consumer unit is used for a 2 Kwatt kettle. Socket nearest consumer unit is in an seldom occupied office and is only used for a cordless telephone's wall wart transformer.
First sign of trouble was the kettle was taking longer to boil and the blue light seemed to be flickering.
Then the cordless phone handset stopped working. Get the key for the office to use the phone. Strange smell in office and the phone's power lamp is not lit. The phone's wall wart will not come out of the socket.
Not yet confirmed but my hunch is there is a loose connection at the back of that socket and the socket has been wrecked by over heating as 8 amps for the kettle tries to get through the bad connection.
With a ring circuit that single fault would not have damaged the socket. It would have gone un-detected if no routine testing was done but it would not have created a hazard.
Ring mains are single fault tolerant, keeps all the sockets working and avoids the following dangerous situation
Radial with four sockets. Socket furthest from consumer unit is used for a 2 Kwatt kettle. Socket nearest consumer unit is in an seldom occupied office and is only used for a cordless telephone's wall wart transformer.
First sign of trouble was the kettle was taking longer to boil and the blue light seemed to be flickering.
Then the cordless phone handset stopped working. Get the key for the office to use the phone. Strange smell in office and the phone's power lamp is not lit. The phone's wall wart will not come out of the socket.
Not yet confirmed but my hunch is there is a loose connection at the back of that socket and the socket has been wrecked by over heating as 8 amps for the kettle tries to get through the bad connection.
With a ring circuit that single fault would not have damaged the socket. It would have gone un-detected if no routine testing was done but it would not have created a hazard.
So it would have remained a high resistance join which may well have failed in the ten years until the next inspection in which time the join could become open circuit leaving the OCPD over sized.
Not if the OCPD is sized to protect the cable if the ring breaks into 2 radials.
And creates the possibility for a N or L break to make the circuit into 2 radials with inadequate overload protection.
So you're saying that there were clear signs that something was wrong and these were simply ignored.
And that a circuit design which supports that kind of tw*ttish behaviour by the users is a good one.
FFS.
You have absolutely no grounds for saying that. A high-resistance connection can always overheat, and you want to use a circuit design which will mask the presence of a high-resistance connection because you think it's a good idea to mask it.
FFS.
But they aren't, are they.
But they can be, very easily.
1) But they aren't.
2) They never are.
3) Have you read 433.1.5?
2) They never are.
3) Have you read 433.1.5?
You have absolutely no grounds for saying that. A high-resistance connection can always overheat,
FFS.
A high resistance joint wil only overheat if there is current flowing through it. With a radial there is no alternative route. The joint will over heat.
Where did I say it was a good idea to mask it. ?
If you read with an open mind what I wrote you may see what was meant. It was meant that it is a good idea to design a circuit where a single fault will not create a hazard even if that fault is not immediately noticed.
[1] A ring in 2.5 with a 20 Amp MCB
[2] Have you inspected every installation with a ring final.
[3] Not in detail, does it in any way stipulate that a final ring must have an MCB rated too high for a single leg of the cable used ?
If the answer to [3] is yes then the rules are stupid or being mis-interpreted. Like the "electrician" who would not wire a final in 4 mm because the design said that 2.5 mm was the "correct" size.
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