New consumer and supply cable

[Nealy]

I have part rewired my house (to be completed in the near future) to a different position to the old consumer unit. The rewire when finished will have 1x cooker, 2x sockets, 1x electric shower, 2x lights, 1x external supply for small compressor for septic tank, 1x external supply for oil fired boiler and lights and 1x supply for burgular alarm. The cottage is currently supplied by a overhead split concentric cable. The new consumer unit position is 4 meters for the old unit. I have 2 question:-

1. What type and size of cable would be suitable as temp. supply for the new consumer ?

2. How should I split the consumer unit ? Should I use 100 and 30ma main isolators ?

Many thanks in advance.

 

[ban-all-sheds]

I have part rewired my house (to be completed in the near future)

What did you tell the council would be the way you'd comply with Part P?

to a different position to the old consumer unit. The rewire when finished will have 1x cooker, 2x sockets, 1x electric shower, 2x lights, 1x external supply for small compressor for septic tank, 1x external supply for oil fired boiler and lights and 1x supply for burgular alarm. The cottage is currently supplied by a overhead split concentric cable.

• For a circuit to supply a given load (doesn't matter what), how would you go about deciding what cable and protective device to use?
  
  
• How do you calculate maximum demand and how can diversity be used?
  
  
• What are the 3 different types of domestic single-phase supplies provided in this country, how would you recognise them, and what differences do each make to the requirements for the rest of the installation, particularly any outdoor supplies?
  
  
• 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?
  
  
• Do you understand how the way in which you install cables affects how much current they can carry?
  
  
• What are the rules concerning cables concealed in walls, partitions and under floors?
  
  
• What are the rules for cables run outdoors, buried in the ground or overhead?
  
  
• 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?
  
  
• Can you explain 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?

The new consumer unit position is 4 meters for the old unit. I have 2 question:-

Why do you think you have only those 2 questions? Have you considered that there might be things you don't realise you don't know about, and won't ask about because you don't even know they exist?

1. What type and size of cable would be suitable as temp. supply for the new consumer ?

You need to check with your DNO to see what their rules are on how long, and what type, of cable you may install between their meter and your CU.

How should I split the consumer unit ? Should I use 100 and 30ma main isolators ?

Nealy - the fact that you're asking that shows that you have no idea how to design an installation, no idea what the current regulations require, and that you should not be attempting it.

Please get an electrician.

 

[bongos]

1. What type and size of cable would be suitable as temp. supply for the new consumer ?

Depends on the rating of your service fuse and length of tails.

2. How should I split the consumer unit ? Should I use 100 and 30ma main isolators ?

I think you'll struggle to find either a 100mA or a 30mA main isolator - if you do then it will be grossly under spec for a domestic install.

Are you refering to a 100A main isolator or a 30mA (or even 100mA) RCD? These are not the same thing and with respect if you are asking these very basic questions I think you should maybe seek some guidance from an electrician.

 

[sparkiedave]

As others have said, there are way too many variables to even begin here, what you've done so far needs to be checked out, then the power supply and CU can be sorted from there, this really is a job requiring a bit more technical knowledge than you appear to have judging by this thread, I'm not a "you mustn't do this because you're not supposed to" merchant, and if I felt that you weren't out of your depth I would happily answer a few questions, best of luck