Branch off Henley block after meter with swa cable to outbuilding

[DamoZ]

Hi all,

I have a cabin in my back garden that I'd like to supply power to. I'm planning on branching off from a Henley block in my main household meter cupboard and using 15-20 metres of 16mm2 3 core swa cable to go to another consumer unit in the outbuilding. I was planning on putting a 100amp isolator switch in the main meter cupboard between the henley block and the swa but I thought I must also need an MCB/RCD to protect the 16mm2 swa cable run from the main house to the cabin because otherwise there's no protection from overload or shock if something happens to the swa cable? I also have a spare fused switch with the option of 63A, 80A, or 100A fuses that I could use with the 63amp fuse although it's too large to fit into the existing cupboard so I was looking for an alternative. Maybe something like this?

 

[SUNRAY]

Hi all,

I have a cabin in my back garden that I'd like to supply power to. I'm planning on branching off from a Henley block in my main household meter cupboard and using 15-20 metres of 16mm2 3 core swa cable to go to another consumer unit in the outbuilding. I was planning on putting a 100amp isolator switch in the main meter cupboard between the henley block and the swa but I thought I must also need an MCB/RCD to protect the 16mm2 swa cable run from the main house to the cabin because otherwise there's no protection from overload or shock if something happens to the swa cable? I also have a spare fused switch with the option of 63A, 80A, or 100A fuses that I could use with the 63amp fuse although it's too large to fit into the existing cupboard so I was looking for an alternative. Maybe something like this?

What did you put on your planning application about the electrical installation?

 

[Taylortwocities]

I thought I must also need an MCB/RCD to protect the 16mm2 swa cable run from the main house to the cabin

Absolutely. If you know what you are doing then you should already know that is the requirement!

I must also need an MCB/RCD to protect the 16mm2 SWA

SWA does not necessarily need RCD protection

Maybe something like this?

Is an option. but not the right one. That has an MCB of 40amp. Will than be big enough?

But I'll stop there. You should know that providing a new circuit, or a consumer unit is work that is notifiable. With respect you dont appear to have the level of competence to design install and test what you are planning in accordance with BS7671.
Notification to LABC as a DIYer really isnt a practical option.

Find yourself a competent and registered electrician. They'll probably let you dig your SWA trench and other grunt stuff, and then they will the necessary and do all the legal stuff with the local authority.

 

[DamoZ]

Absolutely. If you know what you are doing then you should already know that is the requirement!

SWA does not necessarily need RCD protection

Is an option. but not the right one. That has an MCB of 40amp. Will than be big enough?

But I'll stop there. You should know that providing a new circuit, or a consumer unit is work that is notifiable. With respect you dont appear to have the level of competence to design install and test what you are planning in accordance with BS7671.
Notification to LABC as a DIYer really isnt a practical option.

Find yourself a competent and registered electrician. They'll probably let you dig your SWA trench and other grunt stuff, and then they will the necessary and do all the legal stuff with the local authority.

Yes 40amps will be plenty for now, it's just a home office type building but I may add more loads later so that's why I'm using a bigger cable to future proof it and obviously I'd change the MCB if needed later. I did a course a long time ago to do part P electrics but I haven't done anything major for a long time so quite rusty. I've also not branched out to another consumer unit like this before so although logic tells me what I need to do, I've never done it before so thought I should confirm the details with people that are a bit more familiar with these things on a daily basis . The outbuilding didn't need planning permission because it's just timber-framed and below 2.5m in height. I just needed building control approval. Only the 16mm2 swa cable is specified on the building control plans not the way in which it's connected.

 

[Taylortwocities]

Whatever. The SWA circuit is new, anything you do in the cabin is new. Its notifiable.
IF you want to DIY it you first have to raise a building notice for the electrics,
and pay the fee. Then get yourself a set of calibrated test equipment, and a new copy of the regs

I did a course a long time ago to do part P electrics

Well, Part P is a building regulation, not in any way a measure of your competence. And everything has changed since you did that one day multiple guess exam.

Registered electrician, you need. Sorry

 

[SUNRAY]

With respect you dont appear to have the level of competence to design install and test what you are planning in accordance with BS7671.
Notification to LABC as a DIYer really isnt a practical option.

Which is the reason I posted:

What did you put on your planning application about the electrical installation?

I take it you did apply for planning permission as advised on this thread

Hi everyone I wonder if you can help me...

I'm looking to build a timber framed out-building in my back garden. It seems to be ok under permitted development in terms of size and height but I also want to supply electricity to it and put a toilet in there which is the part I'm not sure about? I want to use it for various purposes, basically just as an extra indoor household space for use as a games room/kids activity room/area to work from home and guest room when friends and family come to stay. I'm also not sure what foundation I need and whether this affects the need for planning permission?

Any help appreciated!

 

[DamoZ]

Which is the reason I posted:


I take it you did apply for planning permission as advised on this thread

I was told it wasn't necessary in the end, I just needed full building control

 

[DamoZ]

Thanks, I think I'll use a 63amp RCD, 50amp MCB and a 100amp isolator switch so I don't need to change anything if I add a bit more load later, everything will be low power int here anyway. I've already put in a full plans building control application which includes electrics which has been accepted by the council so I don't think there's any need for an additional notification? I know an electrician who is happy to check over what I've done and issue a certificate if necessary anyway. The cabin is fully built, water tight and insulated and building control have told me they're happy with it and it's "built better than most builders would build it" which was great news and a relief considering I'd never done it before so just need to move on to the plumbing and electrics now. I'm an electrical, computer systems and software engineer orginally but was more into hardware and software design, with microprocessors etc than higher voltage electrics. I used to design and build different hardware/software systems for different companies as a contractor for different companies. I'm looking to make it an intelligent, airtight and sustanable building that basically heats itself via the sun and maintains the heat with loads of insulation, triple glazed windows and mechanical computer controlled heat deflectors/reflectors that channel the sun in when it's cold and keep it out when it's hot to maintain a comfortable temperature inside without the need for traditional heating. I'll add some solar panels on the roof later too and looking to make them track the sun with actuators and MRUs or similar low cost sensors linked to a database or lookup table that supplies the suns incident angle depending on the time of day and day of the year. A heat recovery ventillation system is also in the pipeline. I've pretty much got it all designed but just need to find the the time to put it all together. It's been a great little project so far and just depends how far I want to take it really

 

[flameport]

. I've already put in a full plans building control application which includes electrics which has been accepted by the council so I don't think there's any need for an additional notification?

Assuming you included electric items with that application, you don't need a separate one.
However you MUST confirm with building control exactly what documents they want regarding the electrical installation.

I know an electrician who is happy to check over what I've done and issue a certificate

But what kind of certificate - and is that certificate the one that building control will want?

63amp RCD, 50amp MCB and a 100amp isolator switch

While those will work, an RCD there is a poor choice, and a fuse would be preferable rather than an MCB.

 

[SUNRAY]

I hate it when people come on forums asking for help without any intention of doing the right thing when the correct advice offered is not what they want to hear.

 

[Murdochcat]

This thread just demonstrates how little DIYers actually know about the installation regs

 

[SUNRAY]

This thread just demonstrates how little DIYers actually know about the installation regs

And the building developement requirements

 

[Murdochcat]

And the building developement requirements

Which form part of the regs we have to comply with

Sadly far too many people don’t give a txss

And EV points need declaring to the DNO

 

[Taylortwocities]

Playing fast and loose with Building Regulations was a major factor in what caused the Grenfell tragedy.

 

[JohnW2]

This thread just demonstrates how little DIYers actually know about the installation regs

I think that probably should read ...
"This thread just demonstrates how little some DIYers actually know about the installation regs"

I have to say that, unfortunately, there have also been threads which ...
"... demonstrate how little some electricians actually know about the installation regs"

Generalisations (blanket tarring with one brush), such as the quote above before my modification, are very rarely correct.