New meter so need distribution circuit to old board

[Donc]

Hello in need of a little guidance

The meter has to move for an extension.

9m from current location

medium size detached house

I plan to split the tails, one to a new board for the extension, the other to

an 80A switchfuse and 10mm2 swa to run 9m to the old board through floor joists

or would 100A switchfuse and 16mm swa be better (I forgot to write down what rating mcbs were there)

p.s. could the tails be split to the switchfuse in the new meter box or would they be best inside with the new board?

 

[kme]

Suggest minimum 16mm (pref. 25mm) for distribution.

I`d go 100A KMF adjacent to meter - henleys (awkward to terminate SWA though, unless you use adaptable box adjacent.......).

MCB ratings won`t tell you the cable size to use - doesn`t really matter, with respect to your question.

KME

 

[Larnacaman]

Why do you need a separate CU for an extension?? I take it this is just an extension to a single dwelling?? Really annoys me, seeing 2 remotely separated CUs to supply what is, a standard sized property. 9 times out of 10 it's totally unnecessary!!!

 

[batty]

Why do you need a separate CU for an extension?? I take it this is just an extension to a single dwelling?? Really annoys me, seeing 2 remotely separated CUs to supply what is, a standard sized property. 9 times out of 10 it's totally unnecessary!!!

If you see some of the jobs I do you would not want to get involved with the existing electrical installation. Better to put in a seperate one that way at lest you know your part is right.

 

[Larnacaman]

If you see some of the jobs I do you would not want to get involved with the existing electrical installation. Better to put in a seperate one that way at lest you know your part is right.

That's not a good enough reason batty, that is like going back to the bad old days when a new fuse board was put in for every system . The CU was brought in with the intention to stop the need for all those stand alone fuse boards. But at least those old fuse boards were all in one place!!! Running separate CUs to supply simple house extensions and the like, is at best not good practice, in my mind it's a total nonsense!!!

In most standard/moderate sized houses with an extension, all that is normally required is some circuits extending, and maybe a couple of new circuits. Nothing to warrant a separate remotely located CU....

 

[kme]

But this is a completely different argument to the query the O/P has : headbang

 

[Larnacaman]

How's that??, ....The OP is talking about running a separate CU for the new extension!! Whether he has to move the existing CU position or not, he's still proposing having a separate remotely positioned CU. And that is what my post(s) were pertaining too!!!

 

[Donc]

The reasoning for the additional cu is that there aren't enough spare ways in existing cu. Admitedly I could extend several circuits. But that would cost the punter more pennys in my time and mean more disturbance to the household.

 

[Larnacaman]

That i'm afraid that's the price of doing things correctly!! If a larger CU is required, then that's what you install, not a separate smaller CU located remotely.

I fail to see how installing a new CU remotely, with all that's involved in doing this. Having to then wire in the separate circuits etc, is going to be that much cheaper than doing the job correctly in the first place!!!

 

[Donc]

If I cut other corners such as run the swa through the cavity and put the kmf in the meter box and make the connections to extend the circuits in the existing cu then i could use the original. Suppose that'll be o.k. and much cheaper for the customer, thanks larnacaman

 

[ianmacd]

There are penty of reasons to have multiple CU's. There are plenty of ways to achieve what the OP is trying to achieve but some have a higher cost than others. The best option would be to relocate the CU to the new location and all the curcuits but thats not a realistic option in most situations. I would prefer to see 25mm SWA too as KME suggests, but I would split the tails on the inside with the new CU and make sure each is labled such that it may not isolate the entire dwelling and with the location of the other one.

 

[Sidewinder]

put the kmf in the meter box

You are not allowed "officially" to install eny equipment in the meter box without the authority of the DNO, as the back board is theirs!!!

 

[batty]

problem is some people do not want to pay to have things done correctly and builders may not want things done correctly either if they quote for work some customers will think this price will cover everything which it cannot. I have lost two much money working for builders and the like. A typical example was a loft conversion. Now the bungalow was fed overhead with supply cable running through loft into cut out and consumer unit in hall but this part of the hall was going to be in kitchen/breakfast room. I suggested meter was put in hall entrance by front door and consumer unit moved. I organised all this and customer also asked me to do a lot of other work above original job. At the end of the job the extras were a lot but the people had asked me to do them but refused to pay. Unfortunately I had given them the certificates not realising they were not going to pay. But this goes to show sometimes it does not pay to do things properly. Do what you have to get your money and get on with the next job.

 

[Larnacaman]

There are penty of reasons to have multiple CU's. There are plenty of ways to achieve what the OP is trying to achieve but some have a higher cost than others. The best option would be to relocate the CU to the new location and all the curcuits but thats not a realistic option in most situations. I would prefer to see 25mm SWA too as KME suggests, but I would split the tails on the inside with the new CU and make sure each is labled such that it may not isolate the entire dwelling and with the location of the other one.

Sorry, but there are not plenty of reasons to have multiple CUs remotely positioned in a standard sized house/property. Cutting costs is not a valid reason, nor is ''because it's easier''. Do the job correctly using a CU that is capable of supplying and housing all the circuits required within the installation.

 

[ianmacd]

Sorry, but there are not plenty of reasons to have multiple CUs remotely positioned in a standard sized house/property. Cutting costs is not a valid reason, nor is ''because it's easier''. Do the job correctly using a CU that is capable of supplying and housing all the circuits required within the installation.

Who are you to decide what is a vilid reason? You have given your opinion so I suggest you leave it there.

---------- Post Auto-Merged at 12:24 ---------- Previous post was made at 12:23 ----------

... At the end of the job the extras were a lot but the people had asked me to do them but refused to pay. Unfortunately I had given them the certificates not realising they were not going to pay.....

Batts. You cant withhold certs for non payment.

 

[Larnacaman]

Who are you to decide what is a vilid reason? You have given your opinion so I suggest you leave it there..

Do you mean while you continue to support and encourage Multiple remotely separated CUs??

 

[ianmacd]

Is there a reg against having multiple CU's?

 

[Larnacaman]

Firstly, i'm NOT saying you should not have more than one CU in a domestic dwelling... Just that it be in the Same location/position!!

The Regs don't specify many aspects of our industry, What were talking about here is more to do with commonsense and being a professional.

Just because the Regs have no mention to these sorts of situations, doesn't mean that it is good practice to install mini CUs for the Kitchen, ...in the kitchen, another CU in the new extension just for the extension, and another CU upstairs for the lighting and power circuits upstairs etc etc, etc... Nothing wrong either, with having a small CU in the garage or work shed. They are basically external installations to the main houses installation. We are talking about standard typically sized houses here, Not sprawling mansions, that would probably NEED separately located CUs....

 

[ianmacd]

Having CU's in each room would be good and would minimise disruption in the event of a fault so you could argue more compliant with the regs than a single CU.

 

[Larnacaman]

Well if you think such domestic installations as Good, and can justify a pigs ear of an installation, ...God help the UK and it's electrical industry!!!