New Build - Supply From Electricity Meter Box To Consumer Unit

[Johnny Jekyll]

For our new build, the main electricity supply will come up through the raft slab into the cavity (via hockey stick), into the recessed electricity meter box. From there we of course need to take the supply to the consumer unit. In the image, you can see the electricity meter box position (red). The consumer unit can be located either on the other side of the same wall high up in the W/C if regulations allow (green), or to the right in the utility (blue).

 

The question is what's the best / safest / correct way to run the supply from the electricity meter box to the consumer unit?

Presume it can't just be run inside the cavity? Should we bring it immediately inside and run it along the wall behind the plaster etc?

And where would you locate the consumer unit? W/C or utility?

 

Many thanks.

[Scoobyrex]

Utility and hide it in a wall cupboard.

 

Pretty sure regulations prevent it from being directly above a toilet/cistern.

 

[Johnny Jekyll]

2 hours ago, Scoobyrex said:

Utility and hide it in a wall cupboard.

 

Pretty sure regulations prevent it from being directly above a toilet/cistern.

 

Thanks for the reply. So would you bring the cable through the wall inside, and then feed it into the location of the consumer unit in the Utility? Perhaps behind the plasterboard? Is there a standard way to run it to the consumer unit?  

Edited May 25, 2021 by Johnny Jekyll

[Scoobyrex]

My understanding is the meter "tails" to the consumer can pass pretty much straight through a cavity wall to a consumer unit,  they cannot be longer than 2M. and cannot run or change direction in a cavity.

 

If they are longer than 2M an intermediary switch/isolator is required.

If the meter tails need to be run to a consumer unit they need to be protected in metal trunking

[Scoobyrex]

5 minutes ago, Scoobyrex said:

My understanding is the meter "tails" to the consumer can pass pretty much straight through a cavity wall to a consumer unit,  they cannot be longer than 2M. and cannot run or change direction in a cavity.

 

If they are longer than 2M an intermediary switch/isolator is required.

If the meter tails need to be run to a consumer unit they need to be protected in metal trunking

 

I'm not an electrician, this is all based on what I have researched for my own install.

[TonyT]

Each DNO is different but the common number is 2or 3 metres max, then you will need to run a sub main with suitable fusing of your own.

 

your local electrician will know this

[Johnny Jekyll]

Thanks so much guys. Managing the project on my own and so much to learn...!

Would love to sit down with someone impartial and go through my project. I spend hours upon hours trying to find answers.

Edited May 25, 2021 by Johnny Jekyll

[Carrerahill]

If I was specifying this at design stage, I would put it in the utility, after the DNO's cut-out install a 100A MCB in a little 2 way enclosure - you may even want to consider a 4 way unit and put in surge protection -  then run out a SWA cable as a submains to the consumer unit. I'd use a 25mm 3 core for the short length and all the additional cost will be.

 

 

 

 

[Johnny Jekyll]

16 minutes ago, Carrerahill said:

If I was specifying this at design stage, I would put it in the utility, after the DNO's cut-out install a 100A MCB in a little 2 way enclosure - you may even want to consider a 4 way unit and put in surge protection -  then run out a SWA cable as a submains to the consumer unit. I'd use a 25mm 3 core for the short length and all the additional cost will be.

 

 

 

 

Awesome info thanks.

[Nickfromwales]

100a is permissible if the tails are 3m or shorter, but if they’re longer then you have to downsize to an 80a fuse at the meter. 
Check with your BCO about the acceptable mounting height of the new CU as there are all sorts of crazy bastards out there mis-quoting regs I assure you. 
You may have to ask for a deviation for the CU to go above the “recommended” knee-jerk height so get your ducks in a row before mounting the CU. 

[TonyT]

https://www.tlc-direct.co.uk/Products/WYDSF100M.html?source=adwords&ad_position=&ad_id=315107931576&placement=&kw=&network=u&matchtype=&ad_type=&product_id=WYDSF100M&product_partition_id=987624279487&campaign=shopping&version=finalurl_v3&gclid=EAIaIQobChMIuvyIwqPl8AIVT7LVCh1SBgu6EAQYASABEgIfhvD_BwE
 

if it’s more than the max permissible you need one of the above units to protect your cable.

 

the one that the DNO supply protects their cable and meter.

[Johnny Jekyll]

Again thanks for this guys. Adding to my notes from all of this ?

 

[TonyT]

2 hours ago, Carrerahill said:

If I was specifying this at design stage, I would put it in the utility, after the DNO's cut-out install a 100A MCB in a little 2 way enclosure - you may even want to consider a 4 way unit and put in surge protection -  then run out a SWA cable as a submains to the consumer unit. I'd use a 25mm 3 core for the short length and all the additional cost will be.

 

 

 

 

You probably wouldn’t get discrimination/selectivity between mcb/rcbos in the consumer unit

 

best to stick to a fuse.

[Carrerahill]

14 hours ago, TonyT said:

You probably wouldn’t get discrimination/selectivity between mcb/rcbos in the consumer unit

 

best to stick to a fuse.

Not if the device is selected properly. Service panels rarely have fuses anymore, even the main incomer will be on a MCCB. We design a lot of hotels and multioccupancy resi and the submains are never on fuses these days.

 

He isn't doing the work, his sparky will spec an appropriate device for the installation.

 

 

 

 

 

 

[TonyT]

Agree with the MCCB. But the previous poster advised a MCB.

[Johnny Jekyll]

Thanks again everyone. Will be studying all of this and going over with the electrician.