Adding a second consumer unit in a extension

[cookie999999]

Hi only recently qualified and gone out on my own just landed my first big job wiring a new extension. I recomended to the client that a second cu for the extension might be a good idea as the existing house wiring is all in need of up dating and did not want to get involved with the old cu unit. The problem I have is that he wants the new cu in the new part and it is 15 meters away from the supply and meter. He has gone out without my advice and bought 20 meters of 25mm tails and earth. Which is not cheap. And I have told him that the tails should not be over 3 meters long. Could I get round this by putting a 100amp isolator after the meter then in to Henley blocks and the reconnect the old cu and then run the tails to the new cu ? Any help would be appreciated

 

[Sintra]

I would be more concerned at how you would run tails for 20 meters and give them adequate protection. IMO a SWA cable would be needed. Why even is the client supplying materials?

 

[Leesparkykent]

exactly what sintra said how would you make this comply?

 

[Guest125]

As above but also if you disconnect the existing board to "chop" into the tails you should be sure the existing installation is safe to re-energise.

 

[Pete999]

Did you tell the client that to do what they wanted would involve running in new tails and what size they would need, without giving them any other options? sounds like you told them that new tails were required and he has gone out and bought them, don't know how you feel but it seems like they don't trust your judgement that much, mind you that's only my opinion, just can;t understand why he has gone and paid for new tails, as has been said how would your method comply IMO SWA would have been the best method.

 

[davesparks]

If the existing house wiring is in need of attention then that needs to be included in the works. What exactly is wrong with it that requires updating?
Whatever you do you will need to ensure the correct bonding is in place so will almost certainly be needing to do work in the existing house to achieve this.

Also the million dollar question is, as always, what have you just qualified as and with what qualifications?

 

[Leesparkykent]

how big is the extension/whats going in there to require 25mm? IMO running a swa over to new consumer unit is a lot of effort and cost when you could just run the new circuits from the extension (same route you would of prob used for swa/tails)and put them on its own consumer next to existing consumer unit. plus you will have to install bonding to gas and water if not already in place.

 

[Guest125]

If the existing house wiring is in need of attention then that needs to be included in the works. What exactly is wrong with it that requires updating?
Whatever you do you will need to ensure the correct bonding is in place so will almost certainly be needing to do work in the existing house to achieve this.

Also the million dollar question is, as always, what have you just qualified as and with what qualifications?

Nooooooooooooo!!! Please not this one again.

 

[telectrix]

Hi only recently qualified and gone out on my own just landed my first big job wiring a new extension. I recomended to the client that a second cu for the extension might be a good idea as the existing house wiring is all in need of up dating and did not want to get involved with the old cu unit. The problem I have is that he wants the new cu in the new part and it is 15 meters away from the supply and meter. He has gone out without my advice and bought 20 meters of 25mm tails and earth. Which is not cheap. And I have told him that the tails should not be over 3 meters long. Could I get round this by putting a 100amp isolator after the meter then in to Henley blocks and the reconnect the old cu and then run the tails to the new cu ? Any help would be appreciated

1. you need a switch/fuse where the fuse has a lower In than the DNO fuse, to protect the DNO fuse from a fault downstream.

2. tails must comply with reg 522.6.101. how you do this is up to you.

 

[Octopus]

Hi only recently qualified and gone out on my own just landed my first big job wiring a new extension. I recomended to the client that a second cu for the extension might be a good idea as the existing house wiring is all in need of up dating and did not want to get involved with the old cu unit. The problem I have is that he wants the new cu in the new part and it is 15 meters away from the supply and meter. He has gone out without my advice and bought 20 meters of 25mm tails and earth. Which is not cheap. And I have told him that the tails should not be over 3 meters long. Could I get round this by putting a 100amp isolator after the meter then in to Henley blocks and the reconnect the old cu and then run the tails to the new cu ? Any help would be appreciated

Matey - if you are going to be the one signing off the work and dealing with the Part P - you and you alone need to design and install and test.

Letting clients supply materials is always going to end in tears.... so tell him he's wasted his money and go and buy the correct materials.

I hope you've got your tin hat on.

 

[D Skelton]

Recently qualified with what qualifications?

 

[HandySparks]

1. you need a switch/fuse where the fuse has a lower In than the DNO fuse, to protect the DNO fuse from a fault downstream.

TBH, providing that the Zs on the distribution circuit is OK, I think you could use the same rating of fuse as the DNO, if that's what you need. It's just there to comply with the DNO's requirements that they're not providing sole protection for long tails. You'd have to go a LOT lower to get reliable discrimination. If the DNO's fuse blows in the event of a fault, it's not dangerous, just inconvenient.

 

[Guest77]

Hi only recently qualified and gone out on my own just landed my first big job wiring a new extension. I recomended to the client that a second cu for the extension might be a good idea as the existing house wiring is all in need of up dating and did not want to get involved with the old cu unit. The problem I have is that he wants the new cu in the new part and it is 15 meters away from the supply and meter. He has gone out without my advice and bought 20 meters of 25mm tails and earth. Which is not cheap. And I have told him that the tails should not be over 3 meters long. Could I get round this by putting a 100amp isolator after the meter then in to Henley blocks and the reconnect the old cu and then run the tails to the new cu ? Any help would be appreciated

What existing earthing arrangement is in the house?
is there any bonding main or supplementry anywhere?
how are you planning to run the cables?
have you told the house owner to take the tails back yet and get some proper cabling for the job?
are you registered with a scheme to sign off the work?
have you got a MFT?
What insurance have you got?
what load is going into the new extension?

 

[Guest77]

Nooooooooooooo!!! Please not this one again.

Why not, I think the question is justified, especially after reading the first post which was pretty worrying.

 

[Guest125]

Why not, I think the question is justified, especially after reading the first post which was pretty worrying.

only because I think I know where it will lead.

 

[Guest77]

Well hopefully the guy will come back and answer some of the questions we asked, we can then re-assess the job, there is a lot more he could tell us which would help us answer his questions, so far we have nothing.

 

[telectrix]

have nothing, i know nothing. i'm from barcelona. que?

 

[Octopus]

This is the classic example of a poor thread where the OP seems to have scarpered.

It should be locked by the mods until the OP comes back with information........... or else it'll just end up in the forum sewer with so many others....

 

[Guest77]

This is the classic example of a poor thread where the OP seems to have scarpered.

It should be locked by the mods until the OP comes back with information........... or else it'll just end up in the forum sewer with so many others....

I have just read his previous 3 posts before this thread, don't build your hopes up.

 

[GMES]

only because I think I know where it will lead.

But if you think about it we have to ask these questions to be able to gauge if the op is up to the job,and also to be able to offer him the best advice based on information we receive.
Think about it, if we just told him how to do the job, we could be putting someone in danger.
If we are not allowed to ask questions and interact with a new member then we may as well all leave the forum and just leave an automated answering system in our place.