Radial to two rings

[Dazzevans]

Gents

Newbie here. I currently have a radial circuit covering the whole house with an old fuse type consumer unit (1930's house). I intend to replace the consumer unit so thought about converting the exisiting radial into two rings (upstairs and downstairs).

Is there any easy way of finding out which socket is the last one on the radial? I have found one with a single cable going in but could this not also be a spur?

Any thanks is appreciated

Darren

 

[holmslaw]

..

 

[ban-all-sheds]

Is there any easy way of finding out which socket is the last one on the radial?

The last socket on a radial.

An interesting topological concept.

Which would be the last socket on this radial circuit?

And where would you split it to make 2 rings?

I intend to replace the consumer unit

What about all the old wiring? What tests and inspections will you carry out on that prior to replacing the CU, and with what equipment?

• For a circuit to supply a given load, how would you go about deciding what cable and protective device to use? (No, you can't just copy what's there because it's going to become your responsibility and what's there might be wrong.)
  
  
• Do you know which circuits can be ring finals and which cannot, and what the advantages and disadvantages of each are? (No, you can't just copy what's there because it's going to become your responsibility and what's there might be wrong.)
  
  
• Do you know what the two main lighting circuit topologies are, and what the advantages and disadvantages of each are?
  
  
• How do you calculate maximum demand and how can diversity be used?
  
  
• Can you correctly identify all components and connections of a circuit by method of testing or otherwise? In doing so can you identify or recognise anything wrong or dangerous with the circuit? You cannot assume that what's currently installed is OK, and you need to check it before starting work.
  
  
• Do you understand how the way in which cables are installed affects how much current they can carry? (No, you can't just copy what's there because it's going to become your responsibility and what's there might be wrong.)
  
  
• Where cables need to be joined, how should this be done / not be done and in what circumstances are different methods acceptable?
  
  
• Can you identify extraneous conductive parts, and do you know the requirements for main and supplementary bonding of them?
  
  
• Which circuits should be RCD protected?
  
  
• How do you propose to isolate your supply so that you can connect up your new CU?
  
  
• Are you going to do any testing yourself, or is your plan to bung it in and hope that when your LABC, or the person they or you appoint, come to test it that everything will be OK?
  
  What if it's not - how much will it cost you to fix it and then pay for a second visit?
  
  If you are going to check your own work do you know what tests you would carry out on the installation - what sequence you'd do them in and at what point you would energise the installation, and for each test do you know what is being measured, why it is important, how you would carry out the test, and with what equipment, and what sort of results you would expect to get if everything was OK?

 

[Dazzevans]

When I said I was looking at replacing it, I meant that I waas getting a professional in. I would like to think that he would pick up on any faults, however after looking under the floorboards and at the sockets etc that I have worked on so far, the wiring looks to be modern.

I have identified that the radial starts on the first floor, and I think I know where it comes through to the lower floor (it runs down through the ceiling into the hall, surface mounted to the wall) and it is about 8 feet from the CU. I would guess that this could be extended and run back to the CU, with the ground floor circuit effectively starting at the socket that this one went to. Then just a case of finding the last "radial" socket and cabling back from here to the CU?

 

[ban-all-sheds]

When I said I was looking at replacing it, I meant that I waas getting a professional in.

Ok - that wasn't clear from

I intend to replace the consumer unit

I would like to think that he would pick up on any faults, however after looking under the floorboards and at the sockets etc that I have worked on so far, the wiring looks to be modern.

You'd better hope he does check and test first, or you could well end up in a world of pain and uncontrolled costs.

I have identified that the radial starts on the first floor, and I think I know where it comes through to the lower floor (it runs down through the ceiling into the hall, surface mounted to the wall) and it is about 8 feet from the CU. I would guess that this could be extended and run back to the CU, with the ground floor circuit effectively starting at the socket that this one went to. Then just a case of finding the last "radial" socket and cabling back from here to the CU?

Firstly, and most importantly - leave all of that to the electrician.

Secondly, why are you so set on the idea of having ring finals?

 

[ban-all-sheds]

Then just a case of finding the last "radial" socket

Which would be the "last" one in this circuit?

 

[Dazzevans]

I would say C was the final socket. But then spurs on a spur (D and E) is a bit naughty isn't it? That's why we employ sparks.

I'm glad aircraft electrics are a lot easier.

 

[RMS]

I would say C was the final socket. But then spurs on a spur (D and E) is a bit naughty isn't it?

I think you have made a good choice in getting am electrician in.

 

[ban-all-sheds]

I would say C was the final socket.

What makes C the last one and not F?

If C had been added after F, or vice-versa, would that make a difference and why?

But then spurs on a spur (D and E) is a bit naughty isn't it?

Please explain why D & E are "naughty" whereas B & C are not.

Also, please explain how you know that the circuit didn't consist originally of A - D - E with the others added later, and why, if it had been done in that order you suddenly become concerned about D & E.

That's why we employ sparks.

Good idea.

I'm glad aircraft electrics are a lot easier.

That circuit I showed you is more complex than anything found in an aircraft?

 

[cozycats]

OK BAS E,C and F but depends really on the highest Zs.
To the OP
Are you sure that you haven't got an upstairs ring with drop-down spurs to downstairs sockets? in which case upstairs ring simples....downstairs ring NOT!!!

 

[mikhailfaradayski]

Hi Daz,

When is the electrician coming round to check this?

I think he really needs to

 

[sparkwright]

I would say C was the final socket. But then spurs on a spur (D and E) is a bit naughty isn't it? That's why we employ sparks.

I'm glad aircraft electrics are a lot easier.

I'm not sure if you fully understend the implications of converting a radial circuit into a ring.

On a socket radial circuit you can spur or branch off any socket in any way. On a ring you are severely limited in how you spur off it. So if your radial has various branches like in Ban's diagram you won't be able to make a ring out of it.

Establish the age of the radial, how it's wired, if you have enough sockets, are they surface mounted or on skirting boards, and then consider if it's worth re-wiring completely with new ring circuits.

Cue tiresome debate rings v radials.

 

[ban-all-sheds]

Before we do that, cue the as-yet unanswered question:

why are you so set on the idea of having ring finals?

 

[mbga9pgf]

Before we do that, cue the as-yet unanswered question:

why are you so set on the idea of having ring finals?

http://www.ft.com/cms/s/0/4eab2164-d623-11df-81f0-00144feabdc0.html

 

[flameport]

http://www.ft.com/cms/s/0/4eab2164-d623-11df-81f0-00144feabdc0.html

That link just wants you to register - no information.